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Guideline for the Prevention and Control of Norovirus Gastroenteritis Outbreaks in Healthcare Settings, 2011

Evidence Table Q3 - Components of an outbreak prevention/containment program

Author, Yr (Ref) Study Design Quality Study Objective Population & Setting N Results Comments Ref ID_Data extracted by

Dalling, J; 2004 153

Systematic review


To identify if environmental contamination contributes to prolonged or recurring outbreaks and to clarify appropriate terminal cleaning measures. 

Search of Health Electronic Resources Online in Northern England (HEROINE). Databases included Books@Ovid, MyOvid@Hand, journals@OvidFullText, Cochrane Database of Systematic Reviews, American College of Physicians Journal Club, DARE and CCTR, Allied and Complementary Medicine, Cumulative Indsex Nursing and Allied Health, EMBASE, PREMEDLINE and MEDLINE (1996 to present), British Nursing Index, and the National Research Register.
Websites included the Department of Health, Public Health Laboratory Service, CDC, Infection Control Nurses Association, and the World Health Organization.

Search terms included ("Norwalk" OR "norovirus" OR "Winter Vomiting" OR "Viral gastroenteritis" OR  "SRSV" OR "Calicivirus") AND ("Outbreak" OR "Management" OR "Environment" OR "Disinfect" OR "Decontaminate" OR "Decontamination" OR "Clean" OR "Contaminate" OR "Contamination" OR "Precautions" OR "Control").

Limited to English language. Articles excluded if unrelated to viral gastroenteritis, environmental contamination, concentrated on the source of infection (i.e., food borne gastroenteritis), or laboratory diagnosis techniques. References of articles reviewed to identify additional relevant articles. Articles critiqued using a tool adapted from Cormack.

11 articles.
5 articles underwent environmental sampling.

Transmission due to environmental contamination
Identified that environmental contamination occurred during outbreaks – 5/11 (55%)
Environmental contamination considered cause of transmission – 9/11 (82%)
Identified environmental contamination as cause of prolonged or recurring outbreaks – 0%

Environmental sampling
Identified environmental contamination – 3/5 studies
76/210 (36%) swabs positive from curtains, cushions, carpets, lockers, commodes, toilet rims, seats and handles, taps, basins, telephones, door handles, physiotherapy instrument handle, and horizontal surfaces above and below 1.5 meters including light fittings and mantelpieces.

Laboratory testing methods
Studies using RT-PCR – 100%
Two studies recognized that RT-PCR positive for norovirus does not necessarily represent viable virus.

Sampling methods
Methods of specimen collection
3 used saline or transport medium moistened swabs for sampling.
1 used dry swabs.
1 used wet and dry swabs.
There were more positive swabs in studies that used moistened swabs.
Timing of collection
Unclear in 3 studies whether swabs were taken before or after environmental cleaning.
Selection of sampling sites
4 studies did not explain why certain sites were swabbed and did not identify total swabs taken from each site.

Virus survival
1 study reported 21-28 day survival in a dried state at room temperature.
2 studies reported virus survival for at least 12 days; 1 paper repeated sampling and did not find virus in a previously contaminated environment after 5 months. 1 paper suggested that carpets may have viable virus for at least 12 days that is not removed by routine vacuum cleaning.

Changing curtains
2 studies recommend changing curtains, but there is no evidence addressing whether changing curtains would prolong an outbreak.

Carpet decontamination
3 studies advised steam cleaning of carpets but there is no evidence that it is effective for norovirus.
1 study identified carpets as a cleaning priority due to high levels of RT-PCR.
1 study recommended steam cleaning carpets and changing curtains as Category II "strongly recommended and viewed as effective by experts in the field and by the working group, based on strong rationale and suggestive evidence, even though definitive studies may not have been done."

Cleaning and disinfection
4 studies recommended and/or performed terminal cleaning.
3 papers recommended a cleaning or disinfectant agent; all recommended hypochlorite 1000 ppm.
Chadwick recommendations based on Doultree article which recommended glutaraldehyde 0.5% and iodine 0.8%, but not 75% ethanol, quarternary ammonia 1:10 and anionic detergent 1%. The last study gives no reference for the recommendation.
2/5 studies that studied environmental sampling reported decontamination methods; both used 500 ppm hypochlorite, which is no longer advised in current guidelines. 0/5 studies evaluated the effectiveness of currently used disinfectants.

Specific areas for decontamination
4 studies listed recommendations including decontamination of frequently handled objects, taps, door handles, toilets and bathrooms, bath rails, toys, carpets, and surfaces contaminated by stools or vomit.
The only area recommended by > 1 study was bathrooms, despite 2 papers identifying contamination of both toilets and door handles by environmental swabs.

Sample size and power not reported.


MMWR; 2008 79

Prospective controlled study.


To investigate an outbreak at an elementary school.

Students and staff at an elementary school in Washington DC in February 2007.
Students – median age 8 years (range 3-12 years); 55% female.
Staff – median age 41 years (range 13-66 years); 92% female.

266 – 207 students and 59 staff.

Risk factors for symptomatic illness
Bivariate analysis: All results RR (95% CI); p value
Being a student – 0.94 (0.66-1.34); 0.76
Being female – 1.13 (0.82-1.56); 0.52
Having an ill contact – 1.76 (1.16-2.67); 0.01
Classroom J (first) – 1.94 (1.34-2.80); 0.02
Library use: 0.94 (0.58-1.52); 0.87
Library computer use: 1.08 (0.41-2.84); 1.00

District of Columbia Department of Health recommended
-more thorough handwashing with soap and water or alcohol-based hand sanitisers
- cleaning all shared environmental surfaces with a diluted (1:50 concentration) household bleach
-cleaning computer equipment (i.e., mice and keyboards)
-excluding ill persons from school for at least 72 hours after resolution of illness

A case of gastrointestinal illness was defined as illness in a student or staff member with nausea, vomiting, or diarrhea, who was at the school February 2-18, 2007.

Power and sample size not reported.


Lopman, BA; 2004 58

Prospective controlled study


To describe norovirus outbreaks in residential homes or hospitals of principally older individuals.

Patients in hospitals and nursing homes in England.
Cases were hospital patients, nursing home residents, and health care staff with ≥2 episodes of vomiting, ≥3 episodes of diarrhea, or both during a 24-hour period. Those with symptoms due to incontinence or ingestion of laxative drugs were excluded.

271 outbreaks – 33 in nursing homes and 238 in hospital units.
4378 cases – 2154 hospitalized patients, 1360 hospital care staff, 505 nursing home residents, and 358 nursing home staff.

Duration of illness
Hospital patients vs. hospital staff, nursing home staff, and nursing home residents (75th percentile); p value – 3 days (5 days) vs. 2 days (3 days); p<0.001

Recovery was slowest in the oldest age group (≥85 years) of hospitalized patients - 40% symptomatic after 4 days

Outbreak is defined as ≥ 2 cases in a hospital functional care unit with dates of onset within 7 days of each other.

Power and sample size not reported.

Promotion of active surveillance (2-tiers of clinical symptoms) to detect cases as a means of prevention of outbreaks


Lopman, B; 2004 164

Prospective controlled study


To identify and report costs of gastroenteritis outbreaks in the UK from 2002 to 2003.

3 hospital systems in Avon, England.

2,154 patients and 1,360 healthcare staff from 227 unit outbreaks.

Attack rates
2,154 patients – 2.21 cases/1,000 hospital-days (95% CI 2.16-2.25).
1,360 healthcare staff – 0.47 cases/1,000 hospital-days (95% CI 0.45-0.50).
Attack rates for staff members lower than for patients: 19.6% (95% CI 16.6%-22.7%) vs 46.8% (95% CI 40.9%-52.8%); p < 0.001.

227 unit outbreaks – 1.33 outbreaks/unit-year (95% CI 1.16-1.51).
Units with outbreaks larger than those without outbreaks – 21.4 vs 12.6, p value < 0.0001.

Unit closure
Duration – mean 9.65 (95% CI 8.5-10.8) days; most extreme was a unit closed for 48 days.

3.57 (95% CI 1.86-5.2) bed-days lost for every day of unit closure.
Estimated 5,443 bed-days lost from gastroenteritis outbreaks.

Empty beds – US $2.24 million or approximately $768,000/1,000 beds.
Staff absence – $771,000 or $249,000/1,000 beds.
Days of illness in working age men, women, and children – $106,000 or $36,000/1,000 beds.
Bed-days lost plus staff absence – $3.15 million or $1.01 million/1,000 beds.
By extrapolation, gastroenteritis outbreaks cost the English National Health Service US $184 million in one year (2002-2003).

Controlling outbreaks
Outbreaks contained faster when units rapidly closed to new admissions (within 4 days of the primary care): 7.9 vs 15.4 days; p=0.0023)

Outbreak defined as ≥ 2 cases in a functional care unit with dates of onset within 7 days of each other.

Case was a patient or medical/nursing staff with vomiting (≥ 2 episodes of vomiting in a 24 hour period) OR diarrhea (≥ 3 loose stools in a 24 hour period) OR vomiting AND diarrhea (≥ 1 episodes of BOTH symptoms in a 24 hour period) but excluding long standing diarrhea associated with disability or incontinence and diarrhea associated with laxative drugs.

Costs derived from 1) bed-day loss from new admission restriction for affected units and 2) staff absence from illness. Unit Costs of Health and Social Care 2002 report used to estimate the economic loss from empty beds and staff absence. British pounds (2002) converted to US dollars at the rate of 1 pound: $1.6 based on the 5 year average 1999-2003.  

norovirus detected in 63% outbreaks: confirmed etiologic agent in 61 outbreaks (50%) and detected in a single specimen in 16 outbreaks (13%).


Billgren, M; 2002 165

Prospective controlled study


To describe outbreaks of norovirus gastroenteritis. 

Ten hospitals representing 66% of the hospitals in Stockholm County., Sweden. These included medical and geriatric wards among others. Some medical and geriatric wards were randomly selected as controls.

211 wards

Risk of an outbreak of norovirus gastroenteritis on a ward
Outbreak during the previous year (P<0.01)

Lessons learned

  • Hospitals that applied stringent measures to viral spread such as avoiding transfer of patients and staff and emphasizing hygiene routines during the first week of a suspected outbreak could shorten and restrict the outbreak. In hospitals where these measures were introduced late, the outbreak spread to other wards.
  • It was not evident if other measures to any appreciable extent contributed to the shortening of the outbreaks. It was not obvious if measures such as keeping staff off duty until they had been asymptomatic for 48 h or closure to admission of new patients influenced the outcome of an outbreak.

The inclusion criteria for an outbreak were those of Kaplan in at least 3 persons during one week.

Stool samples were analyzed using EM and RT-PCR

Power and sample size not reported.


Evans, M; 2002 83

Prospective controlled study


To describe an outbreak of norovirus gastroenteritis following vomiting by an attendee at a concert 

Primary school children attending a concert at a metropolitan concert hall. Demographic characteristics not provided.

1229 children from 15 primary schools

Description of outbreak
Following the vomiting, cleaning was done with an ordinary vacuum cleaner the following day. No hypochlorite based product was used. The index case was seated in tier 13. Several cases documented from exposure after initial concert, ie. index case not present but exposure continued

Auditorium seating as a risk factor for norovirus infection (follow-up not clearly reported)
Children seated in tiers 9-13 vs. children seated elsewhere – 199/387 vs. 58/797; RR(95% CI) = 7.1(5.4-9.2)

A case was defined as a person who had attended the concert hall and had developed vomiting and/or diarrhea within 24-72 hrs of the visit.

NLV was confirmed in fecal samples using RT-PCR


Lachlan, M; 2002 84

Prospective controlled study


To describe an outbreak of norovirus gastroenteritis and lessons learned.

Persons with a connection to a hotel linked to the outbreak or ill contacts of people who were unwell and had a connection with the hotel.

112 potentially exposed, 79 cases

Symptomatic norovirus infection - Food specific attack rates
Beef sandwich – 1.35(1.08-1.67)
Cheese sandwich – 1.33(1.06-1.67)
Egg sandwich – 1.49(1.18-1.88)
Ham sandwich – 1.39(1.14-1.69)
Lamb sandwich – 1.46(1.28-1.66)
Tuna sandwich – 1.27(1.02-1.60)
Sausage sandwich – 1.01(0.77-1.32)
Soup – 1.28(1.00-1.64), P<0.05
Parsley garnish – 0.71(0.18-2.83)
Tomato garnish – 1.15(0.82-1.61)
Hot chocolate – 1.45(1.28-1.65)
Tea – 1.04(0.81-1.33)
Coffee – 1.36(1.10-1.67)
Ice – 1.25(1.00-1.57)
Other drinks – 1.52(1.12-2.05)

After applying a critical P value (<0.003) with Bonferroni correction, only egg sandwich and drinks from the bar (other drinks) were found to be statistically significant.


Lessons from the outbreak

  1. Outbreak control team meetings that are formally minuted with action points being highlighted on a flipchart
  2. Good liaison with laboratory services to agree on clear pathways for the delivery and analysis of samples that became available during normal working hours or were processed over the weekend.
  3. Rapid virological confirmation to reassure the public that appropriate control measures were in place and handle the media interest.
  4. Joint visit to the outbreak premises by protective services and public health representatives to facilitate clear and open communication between all parties and secure a voluntary agreement from the hotel owner to cease all food preparation.
  5. Food handlers should remain off work from onset of illness until 48 hours after diarrhea and vomiting have ceased
  6. All those involved in carrying out interviews and analyzing data working from one site and through one computer network to improve the efficiency of working through contact lists, allowing rapid assessment of the epidemic curve and symptom pattern and the results of RR calculations of the foodstuffs.

A case was defined as someone with symptoms of diarrhea, vomiting or abdominal pain or any combination of these more than once in 24 hours and a connection with the hotel where the outbreak started.

norovirus was confirmed by EM


Love, S; 2002 85

Prospective controlled study


To describe an outbreak of gastroenteritis and procedures implemented to control it.

Guests and employees of a Virginia hotel. There were 3 groups:
Group A: Attendees of a business conference (n=110); median age of cases (n=34) 52 years; 59% cases female
Group B: Physicians and their families (n=95); median age of cases (n=11) 31 years; 73% cases female Group C: Retired persons (n=310); median age of cases (n=15) 71 years; 60% cases female

60 cases

Risk factors for symptomatic norovirus infection (follow-up unclear)
Attending reception: RR(95% CI) – 2.1(1.1-4.0)
Eating coleslaw at picnic: RR(95% CI) – 3.6(1.0-13.6)

Infection control measures instituted:

  1. Employees who were ill in the past two weeks or had an ill child in diapers were excluded from work for 1 day. Employees who were currently ill with vomiting or diarrhea were told not to work for 1 day after resolution of symptoms
  2. All employees were instructed about hygiene and hand washing 5 days after initial cases
  3. The facility was closed for 8 h to permit thorough cleaning of all food service areas and guest rooms. New guests were not accepted until all guestrooms, bathrooms, and common rooms were thoroughly cleaned 7 days after initial cases
  4. All cold food requiring hand-preparation was excluded from the menu. No open bowls of food such as chips or popcorn were served 7 days after initial cases

Response to intervention (at two week follow-up)
The hotel reported no further ill guests or employees

A case was defined as vomiting or diarrhea in a hotel attendee or staff.

norovirus confirmed by RT-PCR

Power and sample size not reported.


Lo SV, 1994 89

Prospective controlled study


To investigate a SRSV gastroenteritis outbeak in 4 hospitals served by one central kitchen.

4 hospitals - 1 acute district general hospital and 3 smaller peripheral hospitals with long-stay and rehabilitation patients

81 patients and 114 staff in 4 hospitals

Buffet lunch cohort study: n=41 completed quesionnaire

Patient case-control study: 23/24 cases and 35/36 controls completed questionnaires.

Staff case-control study: 22/27 cases and 49/54 controls completed questionnaire.

Buffet lunch study n=41
Food - RR (95% CI)
Ham and tomato – RR 1.0 (0.6-1.7)
Cheese and pickle – RR 0.8 (0.4-1.9)
Turkey salad – RR 2.4 (1.4-4.1)
Tuna – RR 1.2 (0.7-2.0)
Sausage roll – RR 1.1 (0.6-1.8)
Cheese and pineapple – RR 1.0 (0.6-1.8)
Sausage mushroom – RR 1.6 (0.-2.9)
Fresh fruit – RR 0.8 (0.3-2.3)
Meringue – RR 0.9 (0.5-1.4)
Orange juice – 1.0 (0.48-2.0)
Wine – 1.0 (0.51-2.1)

Patient case-control study n=23 cases and 35 controls
Risk factor
Food - OR (95% CI)
March 7th
Beel cobble – OR 0 (0-1.7)
Beef crumble –  OR 1.6 (0-11.5)
Mince – OR 0.7 (0.1-3.9)
Sausage and onion – OR 0.3 (0.1-1.3)
Cheese pie – OR 0.2 (0-1.6)
Lamb salad – OR 0.4 (0.05-2.4)
Tuna salad – OR 6.6 (1.0-71.6); p<0.05
Any salad – OR 1.8 (0.5-6.8)
Corn beef sandwich – OR 1.6 (0.1-23)
Any sandwich OR 4.6 (0.6-39)
March 8th
Cod – OR 1 (0.3-3.5)
Chicken curry – OR 0.8 (0.2-2.8)
Flaked fish – OR 0.7 (0.01-15)
Lamb casserole – OR 0.9 (0.2-3.9)
Mushroom pizza – OR 0.3 (0.01-3.9)
Savoury lamb – OR 1 (0.1-9.7)
Beef salad – OR 3.2 (0.2-97)
Chicken salad – OR 2.5 (0.3-31)
Any salad – OR 4.7 (0.9-30); p <0.05
Salmon sandwich – OR 0.2 (0-2.2)
Any sandwich – OR 0.4 (0.04-2.3)
March 9th
Pork casserole   - OR 1.5 (0.4-5.7)
Chicken pie – OR 0.3 (0.1-1.5)
Minced chicken – OR 0.2 (0-1.6)
Cawl – OR 1.6 (0.2-13)
Fishcake – OR 0.5 (0.1-2.5)
Egg salad – OR 0.3 (0-3.9)
Cheese salad – OR 2.2 (0.2-4.8)
Any salad – OR 1.1 (0.2-4.8)
Ham sandwich – OR 0.5 (0.01-6.7)
Any sandwich – OR 1 (0.1-9.7)

Staff case-control study
No statistically significant associations found.

1 food handler who prepared the salad had a child who was ill 2 days prior and the food handler became ill the day following food preparation.

Infection control practices
Closure of the central kitchen
Disposal of all remaining food
Discontinuing all hospital admissions and ward transfers
Daily ward cleaning with 2% hypochlorite
Emphasis on hand washing

A cohort study of staff who attended a retirement buffet lunch, a patient case-control study based at the district general hospital, and a nursing staff case-control study at the district general hospital were performed.

Fecal samples underwent bacteriological examination, routine EM, and immuno-EM.

Power and sample size not reported.


de Wit, M; 2007 92

Retrospective controlled study


To describe an outbreak of gastroenteritis caused by a baker infected with norovirus who continued to work in his bakery having washed his hands and disinfected countertops.

Staff of a department in the Netherlands who attended a reception where the outbreak was reported. Median age 39 years; 45% female.

800-900 employees; 231 reported diarrhea or vomiting

Diarrhea and vomiting – 76%
Diarrhea only – 12%
Vomiting only – 12%
Median time to onset of symptoms – 31 hours

Risk factors for symptomatic infection
All results OR(95% CI)
Univariate analysis
Coffee – 0.3(0.1-0.9)
Tea – 0.7(0.2-2.0)
Milk – 1.3(0.9-1.9)
Butter milk – 1.1(0.7-1.8)
Orange juice – 1.2(0.8-1.6)
Champagne – 1.6(1.1-2.3)
Cheese – 1.5(1.1-2.2)
Brie – 1.1(0.7-1.8)
Ham – 1.5(1.0-2.2)
Beef – 1.2(0.8-1.9)
Tuna salad – 1.6(1.1-2.4)
Salmon salad – 2.2(1.0-4.5)
Egg salad – 1.4(0.9-2.1)
Raisin roll – 0.9(0.6-1.3)
Increasing number of rolls – 2.0(1.6-2.4)

Multivariate analysis
Coffee – 0.4(0.1-0.8)
Raisin roll – 0.5(0.3-0.8)
Number of rolls – 2.0(1.5-2.5)

Intervention implemented

A case was defined as a member of the departmental staff who attended the reception and reported diarrhea (3 or more loose stools a day) or vomiting in the 72 hours following the reception. A control was defined as a member of the department staff attending the reception without diarrhea or vomiting in the 72 hours following the reception.

norovirus infection was confirmed using RT-PCR

The estimated response rate for questionnaires among cases was nearly 100%. The estimated response rate among controls was 40-50%

Power and sample size not reported


Hansen, S; 2007 166

Retrospective controlled study



To perform a systematic analysis of when ward closure was needed.

The Outbreak Database, which includes approximately 75% of all nosocomial outbreaks published in PubMed, was searched to identify how many outbreaks required closure.

1561 outbreaks

Closure rates by ward
Overall – 194/1561 (12.4%)
All results – No. outbreaks with closure/No. outbreaks (rates); p value
General surgery – 44/346 (12.7%); NS
Neonatology – 53/332 (16.0%); NS
Internal medicine – 44/307 (14.3%); NS
Pediatric ward – 8/132 (6.1%); 0.03
Hematology/oncology – 12/125 (9.6%); NS
Geriatrics – 24/79 (30.3%);  <0.001
General medicine – 3/76 (3.9%); 0.03
Hemodialysis – 5/76 (6.6%); NS
Neurology/psychiatry – 7/66 (10.6%); NS
Gynecology/obstetrics – 10/58 (17.2%); NS
Transplantation units – 5/56 (8.9%); NS
Orthopedics – 9/40 (22.5%); NS
Neurosurgery – 9/39 (17.9%); 0.05
Urology – 5/38 (13.2%); NS

Closure rates by pathogen
All results – No. outbreaks with closure/No. outbreaks (rates); p value
S. aureus – 23/223 (10.3%); NS
Hepatitis virus – 6/150 (4.0%); 0.002
Pseudomonas spp – 10/130 (7.7%); NS
Klebsiella spp – 10/115 (8.7%); NS
Acinetobacter spp – 24/105 (22.9%); 0.02
Serratia spp – 14/94 (14.9%); NS
Enterococci – 8/67 (11.9%); NS
Enterobacter spp – 10/66 (15.2%); NS
Streptococci – 19/63 (28.6%); 0.001
Salmonella spp – 4/56 (7.1%); NS
Legionella spp – 2/48 (4.2%); NS
norovirus – 15/34 (44.1%); <0.001
Clostridium spp – 4/34 (11.8%); NS
Aspergillus spp – 5/25 (20.05%); NS
Influenza/parainfluenza virus – 10/26 (38.5%); <0.001
Citrobacter spp – 3/12 (25.0%); NS
Adenovirus – 3/11 (27.3%); NS
Shigella spp – 4/11 (36.4%); 0.04
Rotavirus – 7/27 (25.9%); 0.05
SARS – 4/12 (33.3%); NS

Closure rates by source of outbreak
All results – No. outbreaks with closure/No. outbreaks (rates); p value
Patient – 66/395 (16.7%); 0.03
Environment – 24/194 (12.4%); NS
Medical devices – 12/172 (7.0%); 0.04
Personnel – 17/154 (11.0%); NS
Drugs – 3/73 (4.1%); 0.03
Food – 1/50 (2.0%); 0.03
Equipment for patient care – 5/35 (14.3%); NS
Source not known – 80/518 (13.8%); NS

Closure rates by route of transmission
All results – No. outbreaks with closure/No. outbreaks (rates); p value
Contact – 124/752 (16.5%); 0.01
Invasive techniques – 13/273 (4.8%); 0.01
Inhalation – 31/166 (18.7%); 0.02
Ingestions – 4/63 (6.3%); NS
Mode not known – 41/404 (10.1%); NS

Closure rates by type of infection
All results – No. outbreaks with closure/No. outbreaks ( rates); p value
Bloodstream infections – 76/589 (12.9%); NS
Gastrointestinal tract – 49/402 (12.2%); NS
Pneumonia – 44/331 (13.3%); NS
Surgical site infection – 21/195 (10.7%); NS
Urinary tract – 23/190 (12.1%); NS
Skin and soft tissue – 21/171 (12.3%); NS
Other lower respiratory tract – 21/134 (15.7%); NS
ENT – 24/109 (22.0%); 0.004
CNS – 23/95 (24.2%); 0.001
Other systemic infections – 7/49 (14.3%); NS
Bones and joints – 5/44 (11.4%); NS
Cardiovascular system – 4/34 (11.8%); NS

Duration of closure described in 32 outbreaks – median, 14 days (range, 3-56).

Interventions for all outbreaks, not limited to norovirus
-Closure of entire unit (69.6%)
-Infected or colonized patients isolated (66%)
-Patient screening cultures and surveillance (58%)
-Staff screening cultures and surveillance (49.5%)
-Enforced hand hygiene (43.3%)
-Reprocessing of devices (43.3%)
-Healthcare worker education (24.2%)
-Work load restriction (16.5%)
-Vaccination (4.7%)

Any partial or total closure of an affected location for any duration included.

Each closure rate compared to the overall closure rate.

Power and sample size not reported.


Zingg, W; 2005 167

Retrospective controlled study


To describe a nosocomial norovirus outbreak, its management, and financial impact.

Patients at a Swiss university hospital.

Age – mean 57.8 years.
Sex – 56% male

16 case patients and 32 control patients.

Symptomatic infection - Attack rate

Overall – $40,675
Laboratory testing
$2707 for laboratory tests (13 tested, 3 based on clinical symptoms)
Loss of revenue due to bed closures

Median numbers of occupied beds: Outbreak vs other non-outbreak periods
29 beds/day in 2003  vs 42 beds/day in 2001, 43 beds/day in 2002, 42.5 beds/day (p=0.002, Mann-Whitney U test).
Differences in median bed occupancy between peak incidence of illness and periods preceding and following (p<0.01).

Costs not included
Nursing care
$10,300 (based on additional nursing care, in minutes)
Nursing care for case vs control patients – All results in median minutes/day; p value
Total – 74.3 vs 41.9; <0.05
Mobilization care – 105 vs 30; 0.05
Control of excretions – 202 vs 127.5; .54
Instructions – 30 vs 30; .42
Isolation measures – 180 vs 0;<0.0001

Difference due to need for isolation of infected cases (median, 180 minutes/day).

Lost productivity costs due to healthcare worker on sick leave
Infection control

-Infected patients isolated until 2 days after diarrhea resolved.
-Gloves and gowns during direct patient contact until 2 days after the diarrhea resolved.
-No new patient admissions or transfers.
-Hand antisepsis and hand washing.
-Rooms decontaminated with 0.5% hypochlorite after patient discharge.
-Infected healthcare workers stayed home and were allowed to return to work 2 days after symptoms resolved.

These measures did not completely prevent new cases, but there was a decrease in the incidence of new cases after these measures were implemented.

Case was a patient or healthcare worker who developed acute diarrhea, nausea, and vomiting during the outbreak period; and had norovirus detected by RT-PCR in stool specimens.
(12 definite cases; 3 probable cases with typical symptoms but not tested; and 1 with typical symptoms but norovirus RT-PCR negative.)

Control was a patient hospitalized during the outbreak on the same medicine ward without symptoms of gastroenteritis, matched by age, sex, underlying disease category, and length of stay. 

Power and sample size not reported.


Oppermann, H; 2001 63

Retrospective controlled study


To identify risk factors for a gastroenteritis outbreak.

Guests and staff at a mother and child health clinic in Germany.

Cases –166 guests and 49 staff.
Data available – 164 guests and 47 staff.

Symptomatic infection -  Attack Rates
Guests 44% - adults 27% and children 54%
Staff 23.4%

All results affected vs. not affected in years; p value
Children – 3.5 vs 6.3; <0.001
Adults – 32 vs 33; NS

Lessions Learned
-Importance of early recognition of norovirus infection
Guests encouraged to wash hands after using the bathroom and prior to each meal.
-Patients informed doctors immediately of any gastrointestinal symptoms.
-Infected persons had limited contact with other guests and limited use of common facilities.
-The staff was told immediately when gastroenteritis reported and instructed about appropriate protective measures.
-The rooms of the infected persons, especially lavatories, were cleaned daily using a virucidal disinfectant.
-Height of tables raised to prevent children from touching food
-Newly arrived guests received meals in separate area from exposed guests
-Vomitus disinfected immediately.
-If an outbreak suspected, the public health department was to be notified.

Case was a person who stayed at the health clinic from October 27 to November 17, 1999 and had vomiting and/or diarrhea at earliest, one day after his/her arrival.

NLV and Astroviruses detected using PCR.

Power and sample size not reported.


Marx, A; 1999 66

Retrospective controlled study


To assess risk factors for gastroenteritis associated with Norwalk-like viruses (NLVs)

Residents and employees at a geriatric long term care facility. 68% residents were female, median age was 83 yrs (range 65-106). 78% of employees were female, median age was 36 yrs. Study was conducted in Washington State.

91 residents and 97 employees

Attack rate
Residents – 52/91 (57%)
Employees – 34/90 (35%)

All results RR(95% CI); P value for the presence of risk factor
Risk factors for gastroenteritis among residents
Physical dependence – 3.5(1.0-12.9);0.02
Respiratory therapy – 2.3(0.8-6.4); 0.20
Antibiotics – 1.6(1.0-2.8); 0.20
Chronic infections – 1.6(0.9-3.0); 0.40
Tube feeding – 1.3(0.7-2.6); 0.70
Disoriented – 1.2(0.8-1.8); 0.60
Diuretics – 0.4(0.2-0.9); 0.02

Risk factors for gastroenteritis among employees
Exposure to vomitus – 2.6(1.1-6.5); 0.03
Gastroenteritis in household – 2.3(1.4-3.6); 0.01
Exposure to residents with gastroenteritis – 2.2(1.0-4.9); 0.05
Resident care – 1.4(0.8-2.5); 0.30
Tap water – 0.9(0.5-1.5); 0.60
Ice – 0.7 (0.4-1.2); 0.20

Effect of protective measures among nursing staff
Gowning – 0.4 (0.1-1.4)
Strict hand washing – 0.7(0.2-1.3)
Use of hand- disinfection gel – 0.8(0.4-1.4)
Laundering work clothes daily – 1.2(0.7-1.3)

A case of acute gastroenteritis was defined as an individual with onset of vomiting or diarrhea during the study period (Feb 12 – Mar 20 1996); diarrhea was defined as ≥2 loose or watery stools in a 24 hr period. A single NLV strain of genogroup II genetically related to Toronto virus was the only pathogen identified. NLVs were identified by EM in stool and vomitus specimens and further characterized by RT-PCR and nucleotide sequencing.

Data on residents was collected through medical records. 90 of 97 employees completed a self-administered questionnaire

Power and sample size not reported


McEvoy, M; 1996 102

Retrospective controlled study


To describe an outbreak of norovirus gastroenteritis.

Passengers and crew of 4 cruises in the western Mediterranean. Median age of cases 55 years; 13/23 males

46 (23 cases and 23 controls)

Risk factors for symptomatic norovirus infection (matched pairs analysis)
All results OR; P value
Gala dinner – 0.20; 0.22
Salad – 1.00; 0.77
Fruit – 0.56; 0.42
Eggs – 0.50; 0.38
Table – 1.33; 1.00
Taps – OR not calculable; 0.24
Ice (tap water) – 0.56; 0.42
Teeth (tap water) – 1.00; 0.77
Pool – 0.71; 0.77
Chicken – 0.50; 0.39
Prawns – 0.29; 0.18
Meat – 1.14; 1.00
Cream – 0.67; 0.75


  1. Hygiene measures were introduced in the galley
  2. When the passengers disembarked for a short period, the cabins were cleaned with a chlorine based disinfectant
  3. Soft furnishings were removed for steam cleaning from all cabins whose occupants had reported illness. At the same time, the crew and staff quarters, including communal bathrooms and lavatories, were cleaned in the same way.                          

Response to outbreak
After control measures were implemented, fewer than 10 cases of diarrhea and/or vomiting were detected on each of the fifth and sixth cruises

A primary cabin case (the first case to have occurred in a cabin) was defined as a passenger on the ship from 27 May to 2 June with diarrhea (≥3 loose stools in a 24 hour period) and/or vomiting. Controls were matched to cases by sex and age (within 10 years)


norovirus was identified by EM and RT-PCR in fecal specimens

277/1100 questionnaires were completed and returned.

Power and sample size not reported.


Chadwick, PR; 1994 103

Retrospective controlled study


To determine risk factors for small round structured virus infection during an outbreak at an elderly care unit.

Healthcare workers at an elderly care unit.
Cases – mean age 36 years (range 21-58 years).
Controls – mean age 39 years (range 18-59 years).
90% questionnaire responders were female.

103 questionnaires returned.

Clinical features
Overall attack rate – 34%
Attack rates among healthcare subspecialties
Nursing – 40%
Pharmacists – 34%
Doctors – 0%

Staff absent from work due to illness –  75%
Duration of absence – median 2 days (range 1-9 days)

Risk factors for symptomatic infection
Univariate analysis
Nearby vomiting – 50% exposed staff were infected vs. 20% unexposed staff; OR 3.89 (95% CI 1.4-11); p=0.007
Number of exposures to nearby vomiting – p=0.032
Contact with ill patients – 42% exposed staff were infected vs. 13% unexposed staff; OR 4.71 (95% CI 0.94-46); p=0.07
Number of close contacts with ill patients – p=0.023
Cleaning vomit – OR 1.96 (95% CI 0.46-9.8); p=0.49
Cleaning diarrhea – OR 4.67 (96% CI 0.49-225); p=0.22

Multivariate analysis
Nearby vomiting was the only significant risk factor

Interventions Implemented
Handwashing emphasized
Restricted transfers from affected wards
Ward closures
Staff cohorting
Disinfection with chlorine-based products

Attribute declining attack rates among subsequent wards to infection control measures

Case was a patient or staff at the hospital with vomiting or ≥2 loose stools in a 24 hour period.

Power and sample size not reported.

Aerosolization of vomit may have been important in infection transmission during the outbreak.

Exposure to nearby vomiting defined as vomiting occurring within 6 feet of the health care worker.




Johnston, CP; 2007 168

Descriptive study


To describe a norovirus outbreak 

Patients and staff in coronary care and psychiatric units in a tertiary care hospital..

355 cases – 90 patients and 265 health care workers

Mean ages ± SD years – healthcare workers 36.2 ± 10.4 and patients 45.5 ± 23.4.

Female –
83.8% healthcare workers and 47.8% patients.

Attack rates
Cardiac/coronary care unit (CCU) – 7/133 (5.3%) for patients and 29/97 (29.9%) for health care workers.
Psychiatry unit – 39/233 (16.7%) for patients and 76/200 (38.0%) for health care workers.

CCU - Employees used a total of 138 hours of sick leave and 18.5 hours of overtime.

Psychiatry units – Despite routine infection control measures, additional cases occurred.

Costs (US$)
Lost revenue
CCU – $147,507
Cardiac/coronary intensitve care unit (CICU) – $158,620
Psychiatry – $112, 242
Additional costs
Cleaning – $96,961
Replacement of supplies – $53,075
Sick leave and overtime – $89,239
Total – $657,644

At initial outbreak
-Healthcare workers educated on how to identify norovirus gastroenteritis, appropriate cleaning measures, and isolation protocols.
-Infected healthcare workers returned to work 72 hours after symptom resolution.
-Standard precautions and Contact Precautions of symptomatic patients.
-Symptomatic patients in private rooms or cohorted together.
-In the emergency room, symptomatic patients cohorted together.
-Frequent hand hygiene with either soap and water or alcohol based hand gel encouraged.
-Healthcare workers at other institutions not allowed to care for patients at this institution (outbreak was citywide).
-Closure of emergency department at a nearby hospital that had a gastroenteritis outbreak – the outbreak affected the entire city.
-Nurse managers and infection control professionals screened patients and healthcare workers daily, reinforcing infection control practices.
-Nurse managers screened all visitors for gastroenteritis, and if symptomatic, prohibited them from visiting patients in the units for 72 hours.
-Sharing of food among healthcare workers was prohibited.
-Aggressive cleaning measures implemented using 1:50 dilution of sodium hypochlorite (i.e., bleach).
-Every shift, high touch surfaces (i.e., doorknobs, light switches, tables, counter tops, computer keyboards), and bathrooms (particularly toilets and fixtures) cleaned.
-Daily, patient rooms (including walls, windows, beds, chairs, and ledges) cleaned; rooms of patients who vomited or had diarrhea were cleaned last. Floors were cleaned, replacing cleaning solutions and mop heads every 3 rooms.
-At discharge, patient rooms, floors, patient dressers and overbed tables cleaned. Room contents were discarded, the room cleaned, and then restocked. 
-Surfaces soiled or grossly contaminated were cleaned, and curtains changed.

Additional interventions when additional cases identified (implemented 3 days after initial interventions)
-Visitors prohibited, unless extenuating circumstances.
-Nurses on affected floors cohorted – one group cared for symptomatic patients and a second group for asymptomatic patients.
-Gowns and gloves used until outbreak resolved.
-No new admissions in several units because of staffing shortages.
-CCU closed for 24 hours while extensive cleaning occurred.
-All disposable supplies, including medical supplies, discarded.
-Items with fabric surfaces, including furniture, that could not be disinfected were discarded.
-All surfaces cleaned with sodium hypochlorite by two consecutive cleaning crews.
-In the psychiatric unit, group sessions suspended and patients with gastroenteritis confined to their rooms and limited transport of patients to other hospital areas (implemented >1 month after initial interventions on psychiatric ward) 

Cases were those with new onset vomiting and/or diarrhea during the outbreak period. Diarrhea was defined as ≥ 2 loose stools/24 hour period or unexplained increase in bowel movements. 

Norovirus genogroup II-4 variant detected.

Economic analysis focused on the institutional costs of the outbreak from the Johns Hopkins Hospital Casemix administrative database. Costs included total lost revenue with closure of units to new admissions, attributable sick leave and overtime salary, cost of replacing supplies, and cleaning expenses. Analysis limited to CICU, psychiatry units, and echocardiogram laboratory.

Power and sample size not reported.


Leuenberger S; 2007 169

Descriptive study


To describe a norovirus outbreak in a Swiss hospital.

Patients in the geriatric and internal medicine wards where two outbreaks occurred.

77 persons in 2 buildings
– 28 patients and 49 healthcare workers
– 39 in building 1 including the geriatric ward and 38 in building 2, including the internal medicine, intensive care, surgery, orthopedic, and obstetrics and gynecology wards

-Public restaurant in building 1 closed due to an infected staff member.
-Infected healthcare workers sent home for at least 48 hours.
-Infected patients isolated and cohorted.
-Movement of infected patients minimized.
-Healthcare workers and visitors wore masks, gloves, and gowns.
-Mandatory hand disinfection with a product that has 95% ethanol.
-Daily surface disinfection.

Case was someone with sudden vomiting and diarrhea, abdominal cramps, fever below 38.5°C, and recovery within 48 hours.

4/18 samples tested positive for norovirus genogroup II cluster 4.

Diagostic testing could not link the two outbreaks.

The authors speculated that the large outbreak resulted from a more virulent and environmentally stable norovirus strain.


Cheng, F; 2006 170

Descriptive study


To provide a practical action plan for effective infection control of a norovirus outbreak in acute pediatric wards

Patients, parents, visitors, health care workers or medical students who developed vomiting or diarrhea and were exposed to inpatients of a pediatric ward within four days of an outbreak.  The setting was a university hospital in Hong Kong.

There were 11 subjects, including 9 patients, 1 visitor and 1 medical student. Of these 6 were females and 5 were males. Age 4 mos. to 22 yrs

1. Isolation of infected patients.

  • Alert the hospital infection control team if ≥3 inpatients developed gastroenteritis after admission.
  • Cohort and isolate all symptomatic cases.
  • Patients exposed but remaining asymptomatic should stay in the original ward and should only be isolated if they develop clinical symptoms.
  • Stop admitting new patients to the ward in a suspected outbreak.

2. Disease surveillance and contact tracing.

  • Define the surveillance period (e.g. four days before the onset of presentation of the index case for a suspected norovirus outbreak).
  • Establish a case definition for the outbreak.
  • Active surveillance and case finding for symptomatic inpatients.
  • Contact tracing of symptomatic cases among medical, nursing and allied health workers, and reviewing sick leave record of hospital staff.
  • Review admission records for phone contacts to trace symptomatic patients already discharged from the ward, and their parents and visitors.
  • Inform the University Health Service to trace medical students participating in the pediatric clerkship.

3. Infection control measures.

  • Stringent contact precautions.
  • Enforce stringent hand hygiene policy in all pediatric wards.
  • Wear gloves, surgical masks and disposable plastic gowns when in contact with symptomatic patients or contaminated environment.
  • Remove toys and magazines displayed in the ward.

4. Environmental cleansing.

  • Use concentrated disinfectant (hypochlorite solution 1000 ppm) for environmental cleansing.
  • Increase the frequency of routine cleansing in the ward (e.g. twice daily).
  • Widen the cleansing area to one square meter surrounding the contaminated area

5. Visiting policy

  • Register all visitors and keep records for 14 days.
  • Restrict the number of visitors to two (i.e. parents only) for each inpatient.
  • All visitors should be screened by a standard questionnaire for symptoms and signs of gastroenteritis.

6. Staff management.

  • Essential medical and paramedical staff who worked in affected ward were not allowed to work in unaffected clinical areas.
  • Non-essential personnel should not be allowed to enter the affected ward.
  • Symptomatic staff should discontinue clinical duties and seek medical advice immediately.

7. Others

  • Posters about hand hygiene should be shown at the entrance of the ward.
  • Departmental seminars to educate staff on proper infection control measures and the clinical features of norovirus gastroenteritis.

Impact of Interventions
The outbreak was terminated within 3 days after the implementation of the infection control measures

Diarrhea was defined as changing from well-formed stool to ≥3 episodes of loose stools per day.

Stool and rectal swab samples were evaluated using RT-PCR


Simon, A; 2006 171

Descriptive study


To describe a norovirus outbreak.

Patients of a pediatric oncology unit in Germany. 14 males, 6 females. Median age 43 months (range 4-288 mos)

20 patients (11 outbreak, 9 sporadic) and 2 relatives

Outbreak description
28.9% stool specimens tested positive for norovirus. Outbreak stopped with the start of the interventions

Viral shedding
Median (Range) in days – 23(3-140) among 12 patients with >2 positive results who underwent weekly testing


  1. Hand hygiene with 95% ethanol
  2. Use of masks when in close contact with symptomatic patients
  3. All patients were tested for norovirus and were isolated in cohorts if positive

All tool samples tested with RT-PCR

Viral shedding was defined as positive RT-PCR

Nosocomial cases were identified as those with start of symptoms at least 24 hours after hospitalization


Conway, R; 2005 172

Descriptive study


To describe the management of an outbreak of norovirus.

Patients and staff at a tertiary care hospital. Demographic characteristics were not reported

Sample size not reported



  1. Patients with loose or watery stools were reported to the Nursing Unit Manager or clinical coordinator for investigation.
  2. Stool specimens or rectal swabs were collected on all patients.
  3. Three wards managed the at-risk patients and patients who tested positive for norovirus during the outbreak. Patients were relocated and isolated from other patients, visitors and staff.
  4. Barriers and signs were used to indicate entry and exit points for the isolated areas.
  5. Dedicated nursing staff were allocated to care for these patients and skill mix and number of staff was assessed and allocated on a daily basis.
  6. Nursing staff allocated to the care of these cohorts of patients were required to wear surgical  scrubs, which were changed when leaving the ward. Any staff member entering the isolated area wore a disposable gown and gloves.
  7. When dealing with explosive feces or projectile vomiting, a P2/N95 mask was worn to prevent staff from being affected by the aerosolization.
  8. Upon leaving the isolated area all gowns, gloves and masks were disposed of and strict hand washing was enforced.
  9. The Nursing Unit Manager assessed the cohorts of patients on a daily basis and provided an updated list.
  10. Any patients who were symptom free for 48 hours were removed from the cohort and transferred to another area of the hospital. If cohort patients were being transferred to another facility, their discharges were delayed until the patients were symptom free for 48 hours.
  11. Each ward involved in outbreak management was closed to any new admissions or transfers during the peak of the outbreak. To limit exposure to the outbreak, visitors were limited to only the immediate family. Children and elderly visitors were discouraged from visiting.
  12. Education was provided to family members.
  13. Disposable crockery and cutlery were arranged for the cohorts and kitchen staff were not permitted to enter the areas. The cleaning process in the kitchen was assessed and met the standard for cleaning the meal trays.
  14. Affected staff members were advised to exclude themselves from work until symptom-free for 48 hours

Cases were patients with loose or watery stools. norovirus confirmed using RT-PCR


Cooper, E; 2005 205

Descriptive study


To describe a norovirus outbreak at a long term care facility.

Patients and staff on 3 wards in a 500 bed long term care facility in Australia.

52 patients and 11 staff.




The infection control team implemented the following measures consistent with the Victoria Department of Human Services guideline "Controlling an Outbreak of Gastroenteritis: Guidance for Institutions":

-No patient transfers between wards or to other institutions.
-Infected patients cohorted.
-Hand hygiene encouraged and alcohol-based handrubs available by every bedside.
-Gowns and gloves worn.
-Detergent and water, followed by a 1,000-ppm solution of sodium hypochlorite used for cleaning.
-Wards closed to new admissions.
-Staff only scheduled to the same ward.
-Visiting restricted.
-Exposed food discarded.
-Staff educated about how gastroenteritis spread, cleaning and disinfection procedures, isolation, transfers, and discharge.
-Infected staff could not return to work until 48 hours after symptom resolution.
-Contact information for the infection control team made available.

The outbreak ended 32 days after the first symptoms of acute gastroenteritis identified.

norovirus genotype 2 detected on 2 of 3 wards.

Power and sample size not reported.


Navarro, G; 2005 174

Descriptive study


To describe an outbreak in a long-term care unit in Spain.

Patients, residents, and staff in a long term care hospital in Spain.

82% female.

Staff - 20-39 years old.
Patients - 70-89 years old.

60 subjects – 32 patients, 19 staff members, 8 patients’ relatives, and 1 relative of a staff member.

Outbreak description
Incubation period of secondary cases – median 48 hours (range 1-7 days).
Attack rate – 25.4% for patients and 41.3% for staff.
Infected healthcare staff who cared for patients at symptom initiation - 84%; 78% of them were in charge of changing bed linens and moving patients.
The outbreak was controlled in 21 days.

-Hand hygiene and unit cleaning/disinfection re-emphasized.
-Staff excluded from work while ill.
-Hand washing with antiseptic soap (chlorhexidine or povidone-iodine). Handwashing involved wetting hands, using liquid soap, scrubbing 15 seconds, rinsing with water, and drying hands with a disposable paper towel.
-Rooms cleaned with 1% aldehyde or 0.1% chlorine-free bleach.

Cases were those who developed diarrhea (≥2 episodes/24 hours) and/or vomiting after detection of the first case.

Secondary cases were relatives of cases who developed symptoms within 24 hours of visiting an ill family member on the ward.

This outbreak met Kaplan criteria.

16/32 stool samples were positive for norovirus genotype 2.

Power and sample size not reported.


Schmid, D; 2005 175

Descriptive study


To describe an outbreak of norovirus affecting an Austrian nursing home and a hospital

Patients and staff of a nursing home and a nearby hospital in Austria. 88% female among nursing home cases and 68% female among hospital cases. In the nursing home, median age of staff cases was 41 years and that of resident cases was 82 years. In the hospital, median age of staff cases was 37 years and that of patients was 81 years.

25 cases in the nursing home and 28 cases in the hospital

Attack rates
Nursing home
Residents – 18/23(73.9%)
Staff – 7/18(38.9%)
Patients – 10/46(21.7%)
Staff – 18/60(30.0%)

Response to outbreak
Nursing home
Hygiene measures were implemented without waiting for virological confirmation. Two more cases among the residents occurred during the first two days after the measures were implemented.
After a total of 16 cases had occurred in 7 days, the hospital authorities instituted control measures after virological confirmation. After these were implemented two staff and two patients fell ill.

The two institutional clusters met the Kaplan criteria for a norovirus outbreak



Weber, D; 2005 176

Descriptive study


To describe an outbreak of norovirus.

A locked pediatric psychiatric unit in North Carolina. Age of patients 6-12 years.

Sample size not reported

Outbreak description
The index patient was a non-compliant 9 year boy with autism and mood disorders who frequently soiled the environment with fecal material. 3 of 4 patients, 10 of 38 permanently assigned staff, 3 staff temporarily floating from other psychiatric units, and five family members developed gastroenteritis. Symptoms reported by 13 staff members included loose or watery stools in 92%, nausea in 85%, abdominal pain in 77%, vomiting in 69% and fever in 31%


  1. The unit was closed to all admissions
  2. All staff with symptoms of gastroenteritis were given sick leave
  3. Ill staff were not allowed to work until asymptomatic for at least 2 days
  4. Staff were precluded from eating and drinking in the unit
  5. The entire unit was treated as an isolation room with all staff performing hand hygiene and then donning gloves and a disposable gown
  6. The unit was extensively cleaned and disinfected several times with 1:10 diluted hypochlorite (household bleach)
  7. Hand hygiene with soap and water     

Impact of interventions (at 30 days after implementation)
No subsequent cases of gastroenteritis were reported 

Patients reported symptoms of gastroenteritis. norovirus was confirmed using RT-PCR in the index patient and 2 staff members.


Lynn, S; 2004 177

Descriptive study


To describe outbreaks in two separate wards in a geriatric rehabilitation hospital and the role of infection control in limiting the spread.

Patients and staff in two wards in a geriatric rehabilitation hospital.

41 cases from the first outbreak.
24 cases from the second outbreak.

First outbreak:
Attack rate – 57.1% for patients and 41% for staff.
Outbreak duration – 14 days.
Duration of ward closure – 11 days.
Duration of staff sickness – mean, 1.2 days.
Outcome – 1 patient died.

Second outbreak:
Attack rate – 56.5% for patients and 18% for staff.
Outbreak duration – 16 days.
Duration of ward closure – 6 days.
Duration of staff sickness – mean, 3.5 days.

Staffing guidelines
-Permanent staff worked in affected ward (wherever possible).
-Staff needed to be symptom free for 48 hours before returning to work.
-Staff without symptoms working in affected ward did not work anywhere else until 48 hours after completion of work in affected ward.
-Casual staff who filled vacancies in affected ward remained there instead of also working on other wards.
-Casual/ bureau staff who had not worked in affected ward during the outbreak allocated to asymptomatic patients in non-infectious rooms.
-All non-essential staff excluded when possible.

Precautions for any outbreak of vomiting and diarrhea
-Standard precautions at all times.
-Hand hygiene stressed including when exiting ward.

Contact precautions
-Gloves and gown used when working in rooms with symptomatic patients.
-Staff carried masks during acute outbreaks and used it if a patient had vomiting or diarrhea or to clean up vomit.

Room placement
-Contact precautions per room.
-No patients transfers to other rooms.
-If a patient was moved, another patient was not moved into the original bed space until the remainder of the room was symptom free for 48 to 72 hours.

-Linen carrier taken to bedside
-Hot water soluble bags and infectious labels used for soiled linen bags.

Cleaning guidelines
-Contaminated surfaces, carpet, flooring, and equipment promptly cleaned and disinfected.
-Shared patient equipment cleaned with diluted Chlorwhite between usage.
-Labeled individual commodes.
-Toilets cleaned after use (wherever possible) with dilute Chlorwhite.

Empty rooms
-Terminally cleaned using Chlorwhite.
-Steam clean carpets at >150 pounds per square inch (psi).
-Bedside curtain changed when patient vomited or had diarrhea.

Cleaning staff for general cleaning
-Protective clothing while working.
-Diluted sodium hypochlorite used for all horizontal surfaces including bedrails, handrails, door handles.
-Toilets cleaned three times a day.

Sodium hypochlorite (Chlorwhite)
-1000 ppm = 10 mls per 500 ml water in spray bottle.
-Solution made daily.
-Bottle and pump cleaned with detergent and water before refilling.

Cases were those with sudden onset of vomiting, with or without diarrhea. Other symptoms could include nausea, abdominal cramps, myalgia, headache, chills, and fever. The person had to have had contact with cases or in the environment/geographic area in which the outbreak was occurring.

norovirus identified from stool sample  using RT-PCR.

Power and sample size not reported.



Khanna, N; 2003 178

Descriptive study


To describe an outbreak of norovirus gastroenteritis.

Patients and healthcare workers at a university hospital in Switzerland. Demographic details not provided.

63 cases

Description of outbreak
There was no evidence for a water-borne, food-borne or environmental source. The source of the outbreak was most likely a patient admitted to the hospital. Once the outbreak was suspected, measures were instituted according to published guidelines, but the application of the guidelines proved difficult.

Interventions from published guidelines (Chadwick, JHI 2000) that were found to be feasible were:

  1. Cohorting nurses
  2. Wearing gloves and gown
  3. Cautioning visitors
  4. Increasing the frequency of routine ward, bathroom and toilet cleaning

Interventions from guidelines that were found to be difficult or not feasible were:

  1. Isolating symptomatic patients
  2. Washing hands with soap after patient contact
  3. Excluding affected staff from the ward immediately and until 48 hrs symptom free (this resulted in severe staff shortage)
  4. Closing ward and avoiding transfer (exceeded hospital resources and frequently multiple wards were affected at the same time)
  5. Using hypochlorite to disinfect hard surfaces (it was thought that hypochlorite may result in incompatibilities with surface composition not resistant with bleach)

Patients suffered from clinical symptoms of acute gastroenteritis. norovirus was identified from fecal specimens by RT-PCR

Study period from 28 February to 20 March 2001


McCall, J; 2002 179

Descriptive study


To describe an outbreak of norovirus.

Staff and patients of an acute elderly ward in Ireland. Demographic characteristics not reported.

58 cases


  1. Where possible symptomatic individuals were nursed in isolation and when no single rooms were available, cohort-nursed
  2. Disposable plastic gown and gloves for staff and visitors; careful hand hygiene
  3. Ward closed to admissions
  4. Non-essential personnel excluded from ward
  5. Transfers of patients to other wards and areas of the hospital were avoided unless medically essential
  6. Not discharged to nursing or residential accommodations; discharge to patient’s own home permitted
  7. Frequency of routine ward, bathroom and toilet cleaning increased to hourly
  8. Staff instructed that vomit and feces spillages be cleaned and disinfected promptly
  9. Hypochlorite used to disinfect hard surfaces after cleaning
  10. Staff who covered wide areas of the hospital advised to visit unaffected wards before affected wards
  11. Medical rotations were altered to avoid cross cover between affected and unaffected wards
  12. Staff advised that if they became unwell they should go off duty immediately and should be free of vomiting and diarrhea for 48 hrs before returning to work
  13. Affected wards were not re-opened until 72 hours after the last new case and 72 hours after uncontained vomiting and diarrhea
  14. Affected wards were terminally cleaned at the end of the outbreak   

Response to intervention
The control measures contained the spread of norovirus infection to one ward and stopped it in a few days 

Case definition: A patient or staff member of the hospital who had acute onset of vomiting and/or diarrhea and who had a direct association with the elderly care ward without a negative sample.

norovirus was confirmed using RT-PCR


Milazzo, A; 2002 180

Descriptive study


To describe an outbreak of norovirus gastroenteritis.

Residents and staff at an aged-care facility, 90/107 were females; 60% resided in the hostel, rest in the nursing home section.

107 residents, 75 staff

The interventions were based on published guidelines (Chadwick et al, JHI, 2000), specifically – staff were advised not to return to work for 48 hours after symptoms resolved.

A case was defined as a person living, working, visiting or epidemiologically linked to the aged-care facility with acute onset of diarrhea or vomiting between 14 August and 3 September 2000.

Norovirus was confirmed with RT-PCR.


Miller, M; 2002 181

Descriptive study


To describe an outbreak of norovirus gastroenteritis

Two aged care facilities and one hospital in Canberra., Australia Demographic characteristics not provided.

281 cases

Description of outbreak
The outbreak lasted 32 days. Attack rates in the aged care facilities were 46.3%, 52.7% and that in the hospital was 55.2%.

Infection control challenges in the aged care facilities

  1. High pressure hoses in pan room
  2. Lack of protective apparel in hose room
  3. Lack of knowledge on body fluid spills
  4. Limited access to spill kits
  5. Lack of procedure for cleaning shower chairs
  6. Inappropriate use of protective apparel when working with sick residents
  7. Lack of adherence to staff sickness procedures
  8. Transfers between institutions during outbreaks

Case definition:

  • at aged care facilities: a person who lived or worked at either institution and developed vomiting or diarrhea
  • at hospital: vomiting or diarrhea

norovirus was detected using RT-PCR


Hoyle, J; 2001 182

Descriptive study


To describe the challenges faced during an outbreak and its management.

Residents, staff and volunteers at a long term care facility in Australia. Demographic characteristics not reported.

76 residents; 25 staff and volunteers


  1. Education (especially about hand washing)
  2. Collaborative development of an outbreak management guideline
  3. Affected units were effectively quarantined until 14 days after the final case report in each unit. Quarantine strategies included:
  • Restricting symptomatic residents to the affected unit
  • Restricting staff and volunteer movements from affected to unaffected units
  • Restricting visitors to one unit per visit
  • Affected staff, visitors and volunteers were deemed to be infectious for 48 hours after cessation of symptoms and were excluded from the facility
  • Physiotherapy and occupational and divisional therapy activities were limited to essential services only. Staff in affected units had to remain there
  • Instigating cleaning regimens for all allied health equipment
  • Gaining the cooperation of nursing staff in actively encouraging volunteers and visitors to utilize the clinical hand washing facilities
  1. Allocating one nurse to care for the affected residents after providing care to his/her unaffected residents
  2. Environmental cleaning – 1% sodium hypochlorite to wipe down surfaces for spills of vomitus and feces, thorough facility wide clean, all continence pads treated as infectious waste, additional mop heads allocated to all the units

Management issues identified

  1. Lack of isolation/cohorting facilities
  2. Movements of nursing staff, allied health staff and large numbers of volunteers
  3. Staff shortages
  4. Lack of clear outbreak management policies and procedures
  5. Perception of the signs of an outbreak (e.g. vomiting and diarrhea) as a normal situation
  6. Issues with cleaning protocols and practices

Positive outcomes

  1. Development of realistic gastroenteritis management guidelines
  2. Development of an effective infection control relationship with staff
  3. Development of a positive relationship with the public health unit
  4. Development of a holistic approach to infection control surveillance, infection management and prevention

Anecdotally, the key interventions were sick leave for staff, limiting the movements of both staff and patients, and early ward closure

A case was defined as any patient with diarrhea and/or vomiting within a 24 hour period. norovirus was confirmed to be the cause of the outbreak


Cunney RJ, 2000 87

Prospective controlled study


To investigate a hospital NLV outbreak.

Hospital outbreak

N= 95 persons: 47 patients and 48 staff.


Infection control practices
-Affected patients were cohorted
-Admissions to and transfers from the geriatric ward were stopped
-70% alcohol hand rub supplemented routine hand washing
-Affected staff sent home until 48 hours after symptoms subsided
-Decontamination procedures changed from standard phenolic solution to 2% hypochlorite solution

Food source
Drinking water from the hospital water supply: 16 symptomatic and 6 nonsymptomatic (p=0.1)

12 (13%) containing SRSV were solid phase immune electron microscopy (SPIEM)
positive for NLV

25 (27%) sampes contained small round featureless virus (SRFV) identified by direct EM and were negative on SPIEM


Power and sample size not reported.


Russo, PL; 1997 183

Descriptive study


To evaluate two outbreaks.

Patients and staff at an extended-care facility for the elderly and an acute care ward with an elderly population.

Area 1 – 40 patients and 20 staff.
Area 2 – 18 patients and 14 staff.

Mean age – 79.1 years (range, 19-99).

Attack rates
First outbreak
Wards B and C – 50%
Ward A – 33%
Second outbreak
Ward X – 49%

Admissions and discharges
-No patients admitted to or discharged from wards until outbreak ceased. -Patients discharged home if symptom free for 48 hours, with information and education, provided by the infection control department, given to patients’ caregivers.

-Visitors restricted to immediate family. Children discouraged from visiting until outbreak ceased.

New cases or patients requiring transfer
-Information sent to infection control on new cases or patients requiring transfer because of clinical deterioration.

Staff illness
-Affected staff remained off work until symptom free for 48 hours.

Nursing care
-Single use gowns and gloves worn when attending to patients with diarrhea and/or vomiting. Gowns were removed and disposed in a linen skip. Gloves thrown away and hands washed.

-Wash or disinfect hands after each patient contact.
-Catering and cleaning staff instructed in hygiene and handwashing procedures by ward nursing staff.

Restricting patient movements
-Patients should not attend other departments such as physiotherapy until the outbreak ceased.
-Physiotherapy and occupational therapy limited to individual wards.

-Staffing for each ward individualized. Staff should not be shared between wards.
-Non-essential staff excluded until the outbreak ceased.

Environmental services staff
-Dedicated catering and cleaning staff required for the period of the outbreak.
-Floors, locker, overbed tables, toilets, handwashing basins and taps, showers, surface areas in clean and dirty utility rooms cleaned with 100-200 ppm disinfectant containing sodium hypochlorite solution.
-The infection control department determined when frequency of cleaning reduced.

Soiled linen
-Soiled linen placed in linen skip. Soiled linen should not be handled once in linen skip. Linen skips require frequent changing to prevent overfilling.

Outcome: 2-3 weeks for the outbreaks declared over despite <24 hours for control measures to be implemented. Emphasized early notification and prompt staff furloughing

Costs (In outbreak 2 alone)
-Nursing staff sick leave - $7,600
-Bed closures - $10,600

Case was patient or staff with vomiting or ≥ 2 episodes of loose stools within a 24 hour period.

Power and sample size not reported.


Stevenson, P; 1994 184

Descriptive study


To describe an outbreak in a hospital for the elderly.

Patients and staff at a UK hospital for the elderly.

95 patients and 69 staff (including 6 visitors) affected.

-Infected patients cohorted.
-Special cleaning of toilet areas in affected wards.
-Symptomatic staff excluded from work for 48 hours after symptom resolution.
-Affected wards closed until 48 hour period with no new symptomatic patients or staff.
-Patients needed 5 days of symptom resolution if being discharged to nursing home or elderly persons’ home and 48 hours if returning to their own homes.

Enhanced Interventions
-Hospital closed 6 days after outbreak initiation until 4 days after the last case symptom free.
-Cleaning regimen using hypochlorite solution (HAZ TABS) and alco-wipes.
-Restricted staff cross-movement and patient communal gatherings.
-Visiting restricted.
-Discharges to nursing and residential homes stopped.
-Guidelines and situation summary given to staff with daily updated press statements.
-Wards symptom free for 4 days given a final deep clean with 2% hypochlorite solution (including carpets, curtains, walls, and other equipment) prior to reopening.
-Reopening prohibited if any staff or patient had diarrhea or vomiting. If only diarrhea, assessment by duty medical officer done to establish if the patient was suffering from viral gastroenteritis.

Norwalk virus confirmed by EM.

A case was a patient or staff with vomiting or diarrhea, with or without other symptoms, at the hospital on or after October 25, 1991. Six visitors were included as staff members.

Power and sample size not reported.


Hudson, JB; 2007 185

Basic science

To evaluate the efficacy of ozone gas from a generator (Viroforce) in inactivating norovirus and its surrogate FCV in dried samples in an office, hotel room, and cruise liner cabin.

Virus samples (50-100uL) were dried in duplicate on surfaces including sterile plastic. Ozone level was maintained at 20-25 ppm for 20 minutes, the rapid humidifying device (RHD) was activated for a 5 minute burst of water vapor, both the generator and RHD were switched off for 10 minutes to allow for incubation in the humid atmosphere, and the scrubber was then turned on to remove all ozone gas. When ozone levels decreased to less than 1 ppm, the door was opened and test samples retrieved for testing.

Results from field test in office following standard ozone protocol
All results: Fraction of control in Pfu (Log10); Fraction of control in RT-PCR (Log10)
FCV :0.012 (-1.92); 0.029 (-1.54)     
FCV + FBS:  0.017 (-1.77); 0.021 (-1.68)
FCV + stool: 0.015 (-1.82); 0.020 (-1.70)

All results: Fraction of control in RT-PCR (Log10)
norovirus sample 1: 0.070 (-1.15)
norovirus sample 2: 0.055 (-1.26)
norovirus sample 3: 0.046 (-1.34)

Results from field test in hotel room following standard ozone protocol
All results: Fraction of control in Pfu (Log10) ; Fraction of control in RT-PCR (Log10)
FCV, bathroom: 0 (<-4.0); 0.077 (-1.11)
FCV, bed: <0.0002 (<-3.7); 0.077 (-1.11)
FCV, table: 0 (<-4.0); 0.075 (-1.12)

Results from cruise liner cabin following standard ozone protocol
Treated (bathroom, bed, and table): <101 Pfu/mL; Surviving fraction <0.0002; RT-PCR surviving fraction 0.003-0.03

Results on different surfaces following standard ozone protocol
All results – fraction of control
Plastic – FCV infectivity ≤6 x 10-5; FCV QRT-PCR 0.0013-0.0016; norovirus QRT-PCR 0.05-0.069
Fabric – FCV infectivity ≤3 x 10-4; FCV QRT-PCR 0.0036-0.0048; norovirus QRT-PCR 0.056-0.065
Cotton – FCV infectivity ≤3 x 10-5; FCV QRT-PCR 0.076-0.079; norovirus QRT-PCR 0.030-0.031
Carpet – FCV infectivity ≤4 x 10-5; FCV QRT-PCR 0.0028-0.0032; norovirus QRT-PCR 0.042-0.059

Virus-containing samples dried onto hard and soft surfaces were equally vulnerable to ozone.

Some potential toxicity issues, especially in areas with high traffic                                                 

Norovirus measured by RT-PCR and FCV by QRT-PCR and virus infectivity assays.

Feline bovine serum (FBS)

Pfu = plaque forming units/mL

Control values
Field test in office
FCV infectivity
5.1 x 104 Pfu/mL
116-218 ng RNA by PCR
norovirus infectivity
norovirus sample 1 = 58.15 ng RNA
norovirus sample 2 = 129.5 ng RNA
norovirus sample 3 = 114.1 ng RNA

Field test in hotel room
FCV infectivity
8.0 x 104 Pfu/mL
415.5 ng RNA by PCR

Field test in cruise liner cabin
FCV infectivity
5.37 x 104 Pfu/mL

Field test for different surfaces
FCV infectivity
2.7-3.6 x 105 Pfu
18.7-57.3 ng RNA
norovirus QRT-PCR
98.6-132.7 ng RNA


Park GW, 2007 186

Basic Science

To evaluate the efficacy of sterilox hypochlorous acid (HOCl) solution (HAS) to reduce norovirus both in aqueous suspensions and on inanimate carriers. HOCl was further tested as a fog to decontaminate large spaces

No. 4 finish-polished stainless steel and ceramic tiles were used as representative nonporous andporous surfaces.

Exposing virus-contaminated carriers of ceramic tile (porous) and stainless steel (nonporous) to 20 to 200 ppm of HOCl solution resulted in > 99.9% (> 3 log10) reductions of both infectivity and RNA titers of tested viruses within 10 min of exposure time.

HOCl fogged in a confined space reduced the infectivity and RNA titers of norovirus, MNV, and MS2 on these carriers by at least 99.9% (3 log10) regardless of carrier location and orientation.

HOCl effectiveness was evaluated using nonculturable human norovirus measured by RT-PCR and two surrogate viruses, coliphage MS2 and MNV.


Poschetto, LF; 2007 187


Basic science

To evaluate the efficacy of an organic acid (Venno Vet 1 Super), an aldehyde (Venno FF Super), a halogen compound (sodium hypochlorite solution), and  peroxide (Oxystrong FG) in inactivating norovirus and FCV.      

Known amounts of virus suspensions were incubated with disinfectants. Viral RNA levels were checked pre- and post-disinfection.


Virucidal efficacies of disinfectants
All results – minutes (titer in log10 RTPCRU/ml)
Organic acid (3%)
FCV – 15 (5); 30 (5); 60 (5); 120 (5)
norovirus – 15 (5); 30 (5); 60 (5); 120 (5)
Organic acid (4%)
FCV – 15 (3); 30 (2); 60 (2); 120 (2)
norovirus – 15 (4); 30 (4); 60 (4); 120 (4)
Organic acid (5%)
norovirus – 15 (4); 30 (3); 60 (2); 120 (2)
Aldehyde (0.1%)
FCV – 15 (5); 30 (4); 60 (5); 120 (5)
norovirus – 15 (5); 30 (5); 60 (5); 120 (5)
Aldehyde (0.5%)
FCV – 15 (4); 30 (4); 60 (3); 120 (3)
norovirus – 15 (5); 30 (5); 60 (5); 120 (5)
Aldehyde (1%)
norovirus – 15 (4); 30 (4); 60 (4); 120 (4)
Aldehyde (2%)
norovirus – 15 (4); 30 (4); 60 (3); 120 (3)
Halogen compound (1%)
FCV – 15 (5); 30 (5); 60 (5); 120 (5)
norovirus – 15 (4); 30 (3); 60 (3); 120 (4)
Halogen compound (6,000 ppm free chlorine)
FCV – 15 (2); 30 (2); 60 (2); 120 (2)
norovirus – 15 (≤1); 30 (2); 60 (≤1); 120 (2)
Halogen compound (1.2%)
FCV – 15 (5); 30 (4); 60 (5); 120 (5)
norovirus – 15 (4); 30 (4); 60 (4); 120 (4)
Halogen compound (7,000 ppm free chlorine)
FCV – 15 (2); 30 (2); 60 (≤1); 120 (2)
norovirus – 15 (≤1); 30 (≤1); 60 (≤1); 120 (≤1)
Peroxide (1%)
FCV – 15 (2); 30 (3); 60 (2); 120 (2)
norovirus – 15 (3); 30 (3); 60 (2); 120 (2)
Peroxide (2%)
FCV – 15 (2); 30 (2); 60 (2); 120 (2)
norovirus – 15 (3); 30 (3); 60 (2); 120 (2)

Disinfectant concentrations and contact times associated with the greatest FCV and norovirus titer reduction
All results Disinfectant [reduction factor (RF) in log10] – Conditions for FCV and norovirus
Organic acid (3) – FCV 4%, 30 minutes; norovirus 5%, 60 minutes
Aldehyde (2) – FCV 0.5%, 60 minutes; norovirus 2%, 60-120 minutes
Halogen compound (≥3) – FCV 1% (6,000 ppm free chlorine), 15 minutes; norovirus 1% (6,000 ppm free chlorine), 15 minutes
Peroxide (3) – FCV 1%, 60 minutes or 2%, 15 minutes; norovirus 1%, 60 minutes or 2%, 60 minutes

All disinfectants, except the aldehyde, were effective on FCV.
According to RT-PCR results, 5% organic acid, 1% peroxide, not less than 2% aldehyde with a contact time of 1 h, and a 1% halogen compound with 6,000 ppm of free chlorine and a contact time of 15 minutes, are required for safe disinfection.

The criterion normally set for virucidal efficacy is 99.9% (3 log10) – these results are highlighted.



Jimenez, L; 2006 188

Basic science study


To determine the virucidal effectiveness of R-82, a quarternary ammonium compound disinfectant. This was prepared as 1:256 dilutions in water with a hardness of 400 ppm calcium carbonate for 10 minutes. Hypochlorite concentrations of 100 ± 10 and 1000 ± 10 ppm were also analyzed as controls.

Feline calcivirus (FCV) suspensions. Study was conducted in New Jersey, US.


Reductions in FCV in log10  MPN/mL at 10 min contact time
Initial testing
R-82 – 6.6 (complete inactivation)
Hypochlorite 100 ± 10 ppm – 3.2
Hypochlorite 1000 ± 10 ppm – 6.6 (complete inactivation)

Confirmatory testing
R-82 – 6.4 (complete inactivation)
Hypochlorite 100 ± 10 ppm – 2.8
Hypochlorite 1000 ± 10 ppm – 6.4 (complete inactivation)



The reduction of infectious virus (defined as FCV with cytopathic effects) were expressed as log10  most probable number (MPN)/mL. The log10  reduction for FCV was calculated as the difference between the disinfectant and plate recovery control.


Kramer, A; 2006 189

Basic science

To test the virucidal activity (reduction in viral titer) of a new hand disinfectant with reduced ethanol content (55%) in combination with 10% propan-1-ol, 5.9% propan-1.2-diol, 5.7% butan-1.3-diol and 0.7% phosphoric acid. For in vivo tests, the test product was compared with 70% ethanol, 70% propan-1-ol and standard hard water.

FCV strain F9 both in vitro and in vivo (fingerpad tests using human volunteers – 3 male, 4 female).


Dilution of test product demonstrating virucidal efficacy (RF≥4) against FCV
80% dilution for a contact time of 0.5 min

Reduction of FCV titers
All results mean log10 RF; P value for comparison with test product
Test product vs. 70% ethanol – 2.38 vs. 0.68; P<0.01
Test product vs. 70% propan-1-ol – 2.38 vs. 0.74; P<0.01
Test product vs. standard hard water – 2.38 vs. 1.39; P<0.01


Virucidal efficacy was measured as log10 reduction in viral titers – called reduction factor (RF). A disinfectant solution was considered to have virucidal efficacy if, within the tested exposure period, the titre was reduced at least 104 fold (RF≥4)


Malik, Y; 2006 190

Basic science study


To evaluate five disinfectants against FCV on various carpets and fabrics to detect percentage inactivation of virus. The five disinfectants tested were:
1. Metricide – activated 2.6% glutaraldehyde (undiluted)
2. Microbac-II – 4.75% o-benzyl p-chlorophenol and 4.75% o-phenylphenol (1:128 dilution)
3. 10% sodium bicarbonate and 10% quarternary ammonium compound (1:32 dilution)
4. GermEX – 70% isopropanol (undiluted)
5. 2.5% sodium bicarbonate and 1.3% glutaraldehyde (1:32 dilution)


  1. 100% cotton
  2. 100% polyester
  3. Cotton blend (35:65 blend of cotton and polyester)


  1. Olefin
  2. Polyester
  3. Nylon
  4. Blended carpet (85:15 blend of nylon and olefin)


All results are percentage inactivation of FCV at 1, 5 and 10 min

1. 100% cotton
Metricide – 99.99; 99.99; 100.00
Microbac-II – 85.63; 73.40; 98.72
Sodium bicarbonate and quarternary ammonium compound – 86.20; 90.00; 97.34
GermEX – 98.26; 99.55; 99.86
Sodium bicarbonate and glutaraldehyde – 95.63; 99.12; 99.55

2. 100% polyester
Metricide – 99.99; 99.99; 100.00
Microbac-II – 71.73; 98.32; 99.00
Sodium bicarbonate and quarternary ammonium compound – 94.56; 90.00; 92.40
GermEX – 82.17; 69.60; 91.60
Sodium bicarbonate and glutaraldehyde – 73.91; 83.52; 96.96

3. Cotton blend
Metricide – 99.99; 99.99; 100.00
Microbac-II – 77.61; 86.20; 95.21
Sodium bicarbonate and quarternary ammonium compound – 99.00; 98.04; 95.43
GermEX – 99.00; 98.04; 96.30
Sodium bicarbonate and glutaraldehyde – 99.38; 99.25; 97.39

1. Olefin
Metricide – 99.91; 99.97; 99.95
Microbac-II – 77.61; 84.25; 73.84
Sodium bicarbonate and quarternary ammonium compound – 0; 62.0; 83.83
GermEX – 60.95; 92.10; 97.00
Sodium bicarbonate and glutaraldehyde – 78.09; 88.00; 96.76

2. Polyester
Metricide – 94.54; 100.00; 100.00
Microbac-II – 88.63; 88.29; 96.91
Sodium bicarbonate and quarternary ammonium compound – 82.72; 77.65; 95.53
GermEX – 88.63; 91.70; 78.72
Sodium bicarbonate and glutaraldehyde – 97.90; 95.10; 98.14

3. Nylon
Metricide – 99.93; 99.95; 100.00
Microbac-II – 38.18; 36.95; 60.26
Sodium bicarbonate and quarternary ammonium compound – 0; 17.31; 17.21
GermEX – 52.72; 93.69; 91.72
Sodium bicarbonate and glutaraldehyde –67.27; 71.73; 90.00

4. Blended carpet
Metricide – 80.00; 97.80; 99.68
Microbac-II – 55.17; 38.00; 68.39
Sodium bicarbonate and quarternary ammonium compound – 80.00; 38.00; 45.90
GermEX – 80.00; 73.80; 68.39
Sodium bicarbonate and glutaraldehyde – 97.58; 91.90; 90.00

% virus inactivation = 100 – (amount of virus from disinfectant-treated pieces/amount of virus from negative-control pieces) × 100. Average of 3 experiments was used. Virus was grown in feline kidney cells.



Malik, Y; 2006 191

Basic science study


To compare the virucidal activity of ethanol and isopropyl alcohol against dried feline calcivirus (FCV). Control was exposure to phosphate buffered saline (PBS).

F-9 strain of FCV. Study was conducted in US.


Percent virus reduction
All results are reductions at a contact time of 1,3 and 10 minutes respectively at each concentration of the disinfectant in %
Ethyl alcohol
10 – 86.49; 91.16; 95.00
20 – 88.37; 88.37; 86.49
30 – 88.37; 81.65; 88.37
40 – 93.70; 99.19; 84.10
50 – 98.28; 97.55; 90.20
60 – 98.11; 98.65; 90.20
70 – 99.19; 98.41; 94.50
80 – 98.43; 98.50; 94.50
90 – 99.35; 97.49; 99.49
100 – 98.46; 97.65; 98.06

Isopropyl alcohol
10 – 95.07; 87.81; 87.81
20 – 80.29; 91.64; 80.83
30 – 90.46; 90.00; 83.13
40 – 99.30; 94.44; 94.75
50 – 99.59; 99.52; 99.12
60 – 99.84; 99.76; 99.79
70 – 97.57; 98.94; 99.47
80 – 97.37; 99.12; 99.46
90 – 97.37; 98.14; 99.57
100 – 97.36; 96.59; 96.65

Summary: Ethanol at 70% and 90%  concentrations was most effective at killing FCV within 1 minute; isopropanol effective at 50% and 70% but  none of the alcohols able to achieve 3 log reduction in FCV (>99.9% kill). 

% virus reduction was calculated as [(Vcontrol – Vtreated)/ Vcontrol] X 100


Malik, Y; 2006 192

Basic science study


To evaluate the efficacy of the following compounds against FCV dried on a stainless steel surface:
1. Sodium Bicarbonate 1% + 1.3% glutaraldehyde
2. Sodium Bicarbonate 2.5% + 1.3% glutaraldehyde
3. Sodium Bicarbonate 1.0% + activated dialdehyde
4. Sodium Bicarbonate 2.5% + activated dialdehyde
5. Sodium Bicarbonate 2.0% + 2.0% hydrogen peroxide

F-9 strain of FCV. Study was conducted in US.


Percent virus reduction
All results are reductions at a contact time of 1,3 and 10 minutes respectively at each concentration of sodium bicarbonate in %
1 – 97.22; 97.22; 98.60
2 – 97.22; 98.14; 99.60
5 – 99.22; 99.40; 99.81
10 – 99.99; 99.99; ≥99.99
20 - 99.99; ≥99.99; ≥99.99
All results are reductions at a contact time of 1,3 and 10 minutes respectively for each disinfectant
Sodium Bicarbonate 1% + 1.3% glutaraldehyde – 99.99; 99.99; 99.99
Sodium Bicarbonate 2.5% + 1.3% glutaraldehyde – 99.99; 99.99; 99.99
Sodium Bicarbonate 1.0% + activated dialdehyde – 99.00; 99.00; 99.99
Sodium Bicarbonate 2.5% + activated dialdehyde – 99.99; 99.99; 99.99
Sodium Bicarbonate 2.0% + 2.0% hydrogen peroxide – 99.00; 99.00; 99.68

% reduction = 100 – (virus counts eluted after test product treatment/virus counts eluted from control well disks) x 100


Kampf, G; 2005 193

Basic science

To investigate the efficacy of 3 ethanol-based hand rubs against FCV on artificially contaminated hands.

German volunteers had their fingers contaminated with virus suspension with or without organic load and decontaminated with one of the 3 ethanol-based handrubs compared to 70% N-propanol or 70% ethanol to determine their efficacy against FCV.

4 volunteers.

Reduction in FCV infectivity
Mean log10 reduction factor hand rub (n=16), 70% ethanol ( n=8): p value
Reference alcohols – N/A, 1.45; N/A
Sterillium Virugaard – 2.17, 1.56; 0.17
Sterillium Rub – 1.25, 1.03; 0.20
Desderman N – 1.07, 1.27; 0.47

Mean log10 reduction factor of hand rub (n=16), 70% propan-1-oll ( n=8); p value
Reference alcohols – N/A, 0.95; N/A
Sterillium Virugaard – 1.63, 0.95; 0.0003
Sterillium Rub – 1.43, 1.09; 0.03
Desderman N – 0.78, 0.97; 0.35

Summary: Ethanol superior to isopropan-1-ol

Cases received
Sterillium Virugard, 95% ethanol, Sterillium Rub, 80% ethanol, or Deserman N, 75.1% ethanol.
Controls received N-propanol (70%, w/w) and ethanol (70%, w/w), which have previously been described to be virucidal against FCV.


Barker, J; 2004 194

Basic science

To study the transfer of norovirus from contaminated fecal material via fingers and cloths to other surfaces using RT-PCR and to assess the effectiveness of detergent and disinfectant based cleaning regimens.

A homogenized clinical fecal sample positive for norovirus genogroup II was used. A fecal sample negative for norovirus was used as a negative control.

Transfer of norovirus by fingers to surfaces
Primary transfer
Fecal sample diluted in phosphate buffered saline was absorbed on toilet paper in a Petri dish. The experimenter’s fingertips were pressed on to the contaminated tissue for 10 seconds, and dried for 15 seconds at room temperature.  Contaminated fingers were then pressed on clean melamine surfaces for 10 seconds and left at room temperature for 15 minutes before testing for norovirus.

Secondary transfer
After allowing contaminated melamine surface to dry at room temperature for 15 minutes, clean dry fingers touched the surfaces and then touched a telephone receiver, a tap handle, and a door handle. Secondary surfaces were left at room temperature for 15 minutes before testing for norovirus.

Cleaning and disinfection studies
6 melamine surfaces were contaminated with 10μL fecal sample and dried at room temperature for 15 minutes. They underwent the following protocols and were sampled for norovirus after cleaning:
1) Untreated control
2) Cleaning with cloth soaked in detergent solution for 10 seconds
3) Cleaning with used cloth initially soaked in detergent solution for 10 seconds, then later rinsed in detergent solution after use, and then used to rewipe the surface for 10 seconds.
4) Hypochlorite disinfectant/cleaner (HDC) applied to surface for 1 minute followed by wiping of surface with cloth soaked in detergent solution for 10 seconds.
5) Similar to 4, except HDC applied for 5 minutes.
6) Gross fecal matter removed from the surface by wiping with a cloth soaked in detergent solution for 10 seconds, followed by surface disinfection with HDC for 1 minute, followed by wiping of surface with cloth soaked in detergent solution for 10 seconds.

Transfer of norovirus by fingers to surfaces
Primary Transfer
4 experiments using 8 clean melamine surfaces:
4 surfaces – all 4 experiments norovirus positive
2 surfaces – 3/4 experiments positive
1 surface – 1/4 experiments positive
1 surface – 0/4 experiments positive

Secondary Transfer
norovirus transferred from primary surface to 4/10 door handles, 5/10 telephone receivers, and 3/10 taps. 

Cleaning and disinfection studies
Methods 1, 2 and 3 failed to eliminate norovirus in 14 experiments even when the cloth was re-soaked and the melamine surface rewiped. If the cloth was used to wipe a second clean surface, norovirus was recovered from that surface and from the fingers of study participants.
Methods 4 and 5 eliminated norovirus from the surface in a portion of cases. When the surface tested negative, second surfaces and fingers also tested negative. norovirus could still be detected in 28% of surfaces at 5 minute and 21% after 1 minute. In cases where norovirus remained, there was 100% transfer to a second clean surface and 75% transfer to fingers.
Method 6 completely eliminated norovirus.

Hypochlorite disinfectant/cleaner (HDC) containing 5000 ppm of available chlorine and 4% (w/v) of an anionic surfactant (supplied by Lever Brothers, Port Sunlight, UK).


Duizer E, 2004 195

Basic Science

To investigate the inactivation of the enteric canine CaCV no. 48 and the respiratory FCV F9.


Thermal inactivation
Inactivation of CaCV and FCV:
4C: <1D inactivation in 2 weeks
20C: 3D inactivation 1 week
Between 37 - 56C: 3D inactivation decreased from 24 hours to 8 minutes
Heating to 71.3C: 3D inactivation in 1 minute

Reduction of infectivity by five cycles of freezing and thawing was 0.44 ± 012 D for CaCV and 0.34 ± 0.18D for FCV

UV inactivation
21 mJ/cm2 for CaCV and 22mJ/cm2 for FeCV: 2D inactivation
34 mJ/cm2 for CaCV and FeCV: 3D inactivation

pH stability
pH<= 5 and pH>=10: >5D inactivation for CaCV 
pH 9: 4D reduction for FeCV and 3D reduction for CaCV
pH 6: 2D reduction for FeCV and 4D reduction for CaCV
pH<=2 and pH>=10: >5D inactivation for FCV

Inactivation by 70% ethanol
Inactivation of CaCV and FCV:
<2D reduction in TCID50 after 8 minutes
3D reduction after 30 minutes

Inactivation by sodium hypochlorite
Up to 30 ppm free chlorine: <1D inactivation
300 ppm: >3D inactivation for CaCV and <2D inactivation for FCV
3,000 ppm: complete inactivation (>5D) of FeCV and CaCV in 10 and 30 minutes at room temperature

D = 1 log10, calculated by dividing the TCID50 of the treated sample by the TCID50 of the untreated sample


Gehrke, C; 2003 196

Basic science

To evaluate the efficacy of 3 types of alcohol against FCV as a surrogate for norovirus on fingertips.

In vitro inactivation experiments
One part virus suspension mixed with one part double distilled water and eight parts alcohol in different concentrations to determine efficacy of alcohol products.

In vivo inactivation experiments
Fingertips of volunteers from Germany were artificially contaminated with FCV to determine the efficacy of virus elimination using different alcohol products.

The tested alcohol products included ethanol, and 1- and 2-propanol.

In vitro inactivation experiments
All results Alcohol with concentration – Reduction in titer in log10 ID50 after different time periods; Time to ≥ 4 log10 reduction in titer
Ethanol 50% - 2.19 at 0.5 min, 3.65 at 1.0 min, ≥4.44 at 3.0 min, ≥4.50 at 5.0 min; 3.0 min
Ethanol 70% - 3.55, ≥3.83, ≥5.00, ≥5.19; 3.0 min
Ethanol 80% - 2.19, 2.97, 3.88, ≥4.25; 5.0 min

1-Propanol 50% - ≥4.13, ≥4.31, ≥5.13, ≥4.73; 0.5 min
1-Propanol 70% - ≥4.06, ≥4.06, ≥4.13, ≥4.13; 0.5 min
1-Propanol 80% - 1.90, ≥3.58, ≥4.13, ≥3.98; 3.0 min

2-Propanol 50% - 2.31, 3.22, ≥4.90, ≥5.47; 3.0 min
2-Propanol 70% - 2.35, 2.90, ≥3.92, ≥4.22; 5.0 min
2-Propanol 80% - 1.35, 1.27, 1.88, 2.38; >5.0 min

Extrapolated data
The following concentrations had the greatest virus-inactivating properties:
Ethanol 67% after 1 min with a log10 reduction factor of 3.8.
2-Propanol 58% after 1 min with a log10 reduction factor of 4.9.
1-Propanol 60% after 30 sec with a log10 reduction factor of 4.3.
In vivo inactivation experiments
All results Alcohol (concentration; exposure time; No. fingertips) – Reduction of FCV titer in log10 ID50 ± SD
Ethanol (70%; 30 sec; 16) – 3.78 ± 0.83
Ethanol (90%; 30 sec; 8) – 2.84 ± 0.64
1-Propanol (70%; 30 sec; 16) – 3.58 ± 0.92
1-Propanol (90%; 30 sec; 8) – 1.38 ± 0.33
2-Propanol (70%; 30 sec; 16) – 2.15 ± 0.50
2-Propanol (90%; 30 sec; 8) – 0.76 ± 0.19
Hard water (N/A; 30 sec; 36) – 1.23 ±  0.44

In vitro experiments showed that 1-propanol was most effective
The greatest efficacy did not occur at the highest concentrations (80%).
In contrast to the in vitro studies, in vivo 70% ethanol showed the greatest efficacy.  



Lin, C; 2003 197

Basic science

To evaluate different hand washing agents against natural and artificial fingernails contaminated with Ecoli and CaCV.

Volunteers from Georgia with artificial and natural nails were artificially contaminated with ground beef containing E coli JM109 or artificial feces containing FCV to evaluate the efficacy of the following agents: handwashing with tap water, regular liquid soap (Ivory, Proctor and Gamble), antibacterial liquid soap, (Dial Gol, active ingredient triclosan) alcohol-based hand sanitizer gel (Purell, 62% ethanol), regular liquid soap followed by alcohol gel, and regular liquid soap plus a nailbrush.

Average age – 45

5 with artificial nails – all female
5 with natural nails – 3 female and 2 male

All six handwashing procedures combined - Before vs after handwashing FCV in -log TCID50 ± SD
Natural nail – 3.06 ± 0.47 vs 1.15 ± 0.75
Artificial nail – 3.69 ± 0.52 vs 2.18 ± 0.98

All results for Handwashing agents – reductions in counts in - log TCID50 ± SD
Tap water
Natural nail – 1.97 ± 0.68
Artificial nail – 1.22 ± 0.86

Natural nail – 1.82 ± 0.46
Artificial nail – 1.89 ± 0.31

Antibacterial soap
Natural nail – 2.26 ± 0.42
Artificial nail – 1.65 ± 0.19

Hand sanitizer
Natural nail – 0.86 ± 0.55
Artificial nail – 0.43 ± 0.47

Soap plus sanitizer
Natural nail – 2.13 ± 0.93
Artificial nail – 1.85 ± 0.69

Soap plus nailbrush
Natural nail – 2.54 ± 0.57
Artificial nail – 0.41 ± 0.79

Combined data
Lower non-statistical reductions of Ecoli and FCV counts obtained for artificial vs natural fingernails (p>0.05).
Significantly higher Ecoli and FCV counts were recovered from hands with artificial vs natural nails before and after hand washing (p<=0.05).
Microbial cell numbers were correlated with fingernail length, with greater numbers for those with longer nails (p>0.05).

Best practices for fingernail sanitation of food handlers may be to keep fingernails short , natural, and scrub with soap and nailbrush when washing hands.

Highlighted p≤0.05


Nuanualsuwan,S; 2002 198

Basic science study


To evaluate ultraviolet (UV) inactivation of feline calcivirus (FCV) and to compare it to hepatitis A virus, poliovirus type 1 and two small, round coliphages (MS2 and φX174).

FCV and other viruses (hepatitis A virus, poliovirus type 1 and two small, round coliphages - MS2 and φX174).


Dose in mW s/cm2 required to reduce viral titer by 1 log10
FCV – 47.85
Hepatitis A Virus – 36.50
Poliovirus type 1 – 24.10
MS2 – 23.04
φX174 – 15.48

The UV inactivation curve of FCV was not statistically different from Hepatitis A virus (P>0.05), but was significantly different from Poliovirus type 1, MS2 and φX174 (P<0.05)



Gulati, BR; 2001 199

Basic science

To use FCV as a surrogate to determine the potential efficacy of disinfectants against norovirus on fresh fruit and produce, and food-contact surfaces.

The following products were tested for their efficacy against FCV on artificially contaminated:
Stainless steel food contact surfaces –5.25% sodium hypochlorite (Fox-chlor, Jane Fox, Minn); 1.75% iodine and 6.5% phosphoric acid (Mikroklene, Ecolab, St. Paul, Minn); three quarternary ammonium compouns (QACs) (Microquat and Oasis 144, Ecolab and UMQ, Chemical Specialties Lab, Fairmont, Minn); 15% peroxyacetic acid and 11% hydrogen peroxide (Victory, Ecolab); and two phenolic products (Lysol IC, Reckitt an Colman, Montvale, NJ, and Microbac II, Ecolab)
Strawberry and lettuce­ - 5.25% sodium hypochlorite (Fox-chlor), QAC (Oasis 144), and 15% peroxyacetic acid and 11% hydrogen peroxide (Victory).

Products tested at one, two, or four times manufacturers’ recommended concentrations for contact times of 1 and 10 minutes.

1 minute contact time
-Not effective in any of the tests and no further details given

10 minute contact time
Food contact surfaces
All results – Log10 FCV reduction ± SD
9% QAC 1:200 (450 ppm) – 0.3 ± 0.05
9% QAC 1:100 (900 ppm) – 0.0 ± 0.0
9% QAC 1:50 (1800 ppm) – 2.3 ± 0.05
10% QAC 1:256 (400 ppm) – 0.7 ± 0.1
10% QAC 1:128 (800 ppm) – 1.0 ± 0.1
10% QAC 1:64 (1600 ppm) – 2.0 ± 0.05

5% QAC and 2% sodium bicarbonate 1:64 (780 ppm of QAC) – 0.4 ± 0.05
5% QAC and 2% sodium bicarbonate 1:32 (1560 ppm of QAC) – 3.3 ± 0.1
5% QAC and 2% sodium bicarbonate 1:16 (3120 ppm of QAC) – 3.4 ± 0.05

5.25% sodium hypochlorite (200 ppm of free chlorine) – 0.3 ± 0.05
5.25% sodium hypochlorite (400 ppm of free chlorine) – 0.3 ± 0.0
5.25% sodium hypochlorite (800 ppm of free chlorine) – 1.1 ± 0.05

15% peroxyacetic acid and 11% hydrogen peroxide 1:2000 – 0.4 ± 0.1
15% peroxyacetic acid and 11% hydrogen peroxide 1:1000 – 0.6 ± 0.05
15% peroxyacetic acid and 11% hydrogen peroxide 1:500 – 3.0 ± 0.0

1.75% iodine and 6.5% phosphoric acid (75 ppm of titratable iodine) – 0.0 ± 0.0
1.75% iodine and 6.5% phosphoric acid (150 ppm of titratable iodine) – 0.0 ± 0.0
1.75% iodine and 6.5% phosphoric acid (300 ppm of titratable iodine) – 2.0 ± 0.1

4.75% o-benzyl p-chlorophenol and 4.75% o-phenylphenol 1:256 – 1.5 ± 0.05
4.75% o-benzyl p-chlorophenol and 4.75% o-phenylphenol 1:128 – 6.2 ± 0.2
4.75% o-benzyl p-chlorophenol and 4.75% o-phenylphenol 1:64 – 7.0 ± 0.2

5% o-benzyl p-chlorophenol and 10.5% o-phenylphenol 1:200 – 0.4 ± 0.1
5% o-benzyl p-chlorophenol and 10.5% o-phenylphenol 1:100 – 0.4 ± 0.1
5% o-benzyl p-chlorophenol and 10.5% o-phenylphenol 1:50 – 5.6 ± 0.2

Fresh produce
All results – Log10 FCV reduction ± SD
15% peroxyacetic acid and 11% hydrogen peroxide 1:2000 – Strawberry 0 ± 0.00; Lettuce 0 ± 0.00
15% peroxyacetic acid and 11% hydrogen peroxide 1:1000 – Strawberry 1.0 ± 0.1; Lettuce 2.0 ± 0.1
15% peroxyacetic acid and 11% hydrogen peroxide 1:500 –  Strawberry 3.0 ± 0.06; Lettuce 3.0 ± 0.06

5.25% sodium hypochlorite (200 ppm of free chlorine) –  Strawberry 0 ± 0.0; Lettuce 0 ± 0.0
5.25% sodium hypochlorite (400 ppm of free chlorine) –  Strawberry 0 ± 0.0; Lettuce 0 ± 0.0
5.25% sodium hypochlorite (800 ppm of free chlorine) –  Strawberry 1.0 ± 0.06; Lettuce 1.5 ± 0.05

10% n-alkyl (50% C14, 40% C12, 10% C16) imethyl benzyl ammonium chloride 1:512 (200 ppm) – Strawberry 0 ± 0.0; Lettuce 0 ± 0.0
10% n-alkyl (50% C14, 40% C12, 10% C16) imethyl benzyl ammonium chloride 1:256 (400 ppm) – Strawberry 0 ± 0.0; Lettuce 0 ± 0.0
10% n-alkyl (50% C14, 40% C12, 10% C16) imethyl benzyl ammonium chloride 1:128 (800 ppm) – Strawberry 1.5 ± 0.1; Lettuce 2.0 ± 0.1

None of the disinfectants were effective when used at manufacturer’s recommended concentration for 10 minutes.
Phenolic compounds used at 2-4 x the recommended concentration inactivated FCV on contact surfaces.
Quarternary ammonium compound and sodium carbonate was effective on contact surfaces at twice the recommended concentration.
Rinsing of produce with water reduced virus titer by 2 log10.
On artificially contaminated produce, only peroxyacetic acid and hydrogen peroxide were effective when used at 4x manufacturer’s recommended concentration for 10 minutes.

An agent was considered effective if the virus titer decreased at least 3 log10 (99.9%) compared to untreated controls – significant results highlighted.

Disinfectants and sanitizers diluted in sterile tap water immediately before use.



Doultree, J; 1999 200

Basic science study


To test glutaraldehyde, iodine, hypochlorite, a quarternary ammonium-based product, an anionic detergent and ethanol for disinfecting activity against FCV. The stability of FCV to increasing temperature in suspension and in dried state was also tested.

F9 strain of FCV. Study was conducted in Australia.

Efficacy of disinfectants against FCV
0.5% glutaraldehyde (Aidal) – complete inactivation
Hypochlorite (Det-Sol 5000) – complete inactivation at 1000 and 5000 ppm
Hypochlorite (White King) – complete inactivation at 5000 but not at 1000 ppm
Quarternary ammonia (Pinocleen) – no reduction
75% ethanol – 1.25 log10 reduction
0.8% Iodine (Sanichick) – complete inactivation
1% anionic detergent – 0.5 log10 reduction

Heat inactivation of FCV
56°C – Inactivated at 60 min, no reduction at 1 and 3 min
70°C – Inactivated at 5 min, detected at 1 and 3 min
Boiling – Inactivated at 1 min

Survival based on state and temperature
4°C – stable
Room temperature – survived for ~20 days
37°C – survived for ~10 days

Dried state
4°C – stable
Room temperature – survived for ~28 days
37°C – survived for ~1-2 days

Complete inactivation represents no detection of FCV


Shin, G; 1998 201

Basic science study


To test the inactivation of norovirus using monochloramine (2 mg/L in 0.01M phosphate buffer solution at pH 8.0) and compare it to the inactivation of Poliovirus 1 and MS2.

Norovirus from the feces of infected human volunteers. Poliovirus 1 and MS2 viruses as controls. Study was conducted in the US.

Not reported

Reduction in viral titer at 3hr (measured by RT-PCR)
norovirus – 1 log10
Poliovirus 1 – 0
MS2 – 0
However, infectivity assays showed 1 log10 reductions in Poliovirus 1 and MS2 at 3h




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