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

Evidence Table Q3 - Virus shedding

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

Murata, T; 2007 148

Prospective controlled study

2,3,4

To describe children infected with norovirus and duration of viral shedding.

Children with acute gastroenteritis who presented to a pediatric clinic in Japan. Median age 18 months (range 3 months to 7 years).

71 (59 included for analysis)

Symptoms
Vomiting 94.9%
Diarrhea 94.9%
Fever 20.3%

Severity of illness
Overall duration of illness – median 5 days

All results children <2 years old vs 2-5 years old; p value           
Duration of illness in days – 7 vs. 3.5; 0.0069
Maximum number of stools – 7 vs. 3; 0.0078
20 point severity score developed for rotavirus – 11 vs. 8; 0.0031

Period of viral shedding (n=26)
Overall in days – median, 16 (range, 5-47)
Patients ≤6 months of age vs >1 year old in days – 42 vs. 10; p=0.0475
Shedding > 2 weeks in children <1 year vs. 1 year vs. 2-3 years of age – 6/8 (75%) vs. 5/7 (71.4%) vs. 2/8 (25%)
Patients ≤6 months – 3/5 shed for long periods (42, 44, and >47 days)

Acute gastroenteritis was defined as the presence of either diarrhea or vomiting at presentation between November 1, 2002 to December 31, 2002.

norovirus was diagnosed using RT-PCR.

Power and sample size not reported.

176_IL

Rockx, B; 2002 149

Prospective controlled study (with a nested case control design)

1,3,4

To describe the natural history of CaCV infections in humans.

The case definition of gastroenteritis was ≥ 3 loose stools in 24 h, vomiting ≥ 3 times in 24 h, loose stools with two additional symptoms or vomiting with two additional symptoms. Additional symptoms included diarrhea, vomiting, nausea, fever, abdominal pain, abdominal cramps, and blood or mucus in stool. Healthy control subjects were selected for the same period and matched with cases by age and geographical location. Demographics not reported – community based population registered through the Netherlands Institute of Primary Health Care. Study conducted in Netherlands.

4860

Ages affected (until day 22 after the onset of symptoms)
Proportion of norovirus gastroenteritis cases was highest in children (age 0.5-17 yrs; proportion 14-19%) and elderly (age ≥ 65 yrs; proportion 13%) 

Clinical symptoms
Clinical manifestations reported by 99 cases with norovirus infection were:
Diarrhea – 87%
Vomiting – 74%
Abdominal pain – 51%
Abdominal cramps – 44%
Nausea – 49%
Fever – 32%
Mucus in stool – 19%
Bloody stool – 0%

Median duration of symptoms (days)
Overall – 5
Age < 1 yr – 6
Age 1-4 yrs – 4
Age 5-11 yrs – 5
Age ≥ 12 yrs – 3

Percentage of infected cases shedding virus
On day 1 – 78%
On day 22 – 26% (Highest in newborns aged < 1 yr)

Clinical information was obtained from medical diaries kept by patients during the 4 weeks after the onset of symptoms.

norovirus was detected by RT-PCR.

Power and sample size not reported

934_RA

Marshall, J; 2001 150

Descriptive study (Case report)

N/A

To report a case excreting high levels of NLV in the absence of any clinical symptoms of gastroenteritis.

An elderly woman (71 yrs) who contracted norovirus infection during an outbreak in Australia

1

Asymptomatic shedding (day 2 and day 5 after resolution of symptoms)

About 5 × 105 NLV virions per gram of feces were detected. These were closely related to Camberwell virus, a GII NLV

Stool specimens were analyzed using EM and RT-PCR

1056_RA

Hedlund, 1998; 151

Descriptive study

1,2,3,4

To describe the role of NLV in pediatric diarrhea and describe asymptomatic shedding

All cases with stool samples positive for NLV

77 cases – 33 community acquired, 47 nosocomial

Asymptomatic shedding
5 of 17 children examined repeatedly excreted virus after the symptoms had subsided.

NLV identified by EM

3554_RA

Chiba, S; 1980 152

Descriptive study

1,3,4

To evaluate viral shedding and duration of illness.

Stool specimens were obtained from CaCV outbreaks in an orphanage in Sapporo, Japan.

61 stool samples.

Stool specimens positive for CaCV
Overall – 29/61 (48%)

Symptomatic patients
All results – positive/tested (%)
Obtained before onset of illness – 0/7 (0%)
Obtained within 4 days after onset of illness – 18/19 (95%)
Obtained days 5-10 – 7/14 (50%)

Asymptomatic patients
All results – positive/tested (%)
3/10 (30%)

Illness not defined

2140_IL

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