Chapter 9: Mumps
Manual for the Surveillance of Vaccine-Preventable Diseases
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Authors: Amy Parker Fiebelkorn, MSN, MPH; Albert Barskey, MPH; Carole Hickman, PhD; William Bellini, PhD
Mumps is an acute viral illness caused by a paramyxovirus. The classic symptom of mumps is
parotitis (i.e., acute onset of unilateral or bilateral tender, self-limited swelling of the parotid
or other salivary gland(s)), lasting at least two days, but may persist longer than ten days. The
mumps incubation period ranges from 12-25 days, but parotitis typically develops 16 to 18 days
after exposure to mumps virus. Nonspecific prodromal symptoms may precede parotitis by
several days, including low-grade fever which may last three to four days, myalgia, anorexia,
malaise, and headache. However, mumps infection may present only with nonspecific or
primarily respiratory symptoms or may be a subclinical infection.
In the prevaccine era, rates of classical parotitis among all age groups typically ranged from
31% to 65%, but in specific age groups could be as low as 9% or as high as 94% depending on
the age and immunity of the group.[4-7] Several articles discuss mumps symptoms as nonspecific
or primarily respiratory, however, findings in these articles were based on serologies taken
every six months or a year, so it is difficult to prove that the respiratory symptoms were because
of mumps or that the symptoms occurred at the same time as the mumps infection.[6, 7] In the
prevaccine era, 15% to 27% of infections were asymptomatic.[4-6] In the post-vaccine era, it is
difficult to estimate the number of asymptomatic infections, because it is unclear how vaccine
modifies clinical presentation. Serious complications can occur in the absence of parotitis.[8, 9]
Prevaccine era complications
In the prevaccine era, mumps gained notoriety as an illness that substantially affected armies
during mobilization. The average annual rate of hospitalization resulting from mumps during
World War I was 55.8 per 1,000, which was exceeded only by the rates for influenza and
gonorrhea. Mumps caused transient deafness in 4.1% of infected adult males in a military
population. Permanent unilateral deafness caused by mumps occurred in 1 of 20,000 infected
persons; bilateral, severe hearing loss was very rare. Before the introduction of the live
attenuated mumps vaccine in 1967, mumps accounted for approximately 10% of cases of
aseptic meningitis in the United States with men afflicted three times as often as women.
Mumps encephalitis accounted for 35.9% of all reported encephalitis cases in the United States
in 1967. The incidence of mumps encephalitis is reported to range from 1 in 6000 mumps
cases (0.02%)14 to 1 in 300 mumps cases (0.3%). Orchitis has been reported in 11.6% to 66%
of postpubertal males infected with mumps.[15, 16] In 60% to 83% of males with mumps orchitis,
only one testis was affected.[4, 9] Sterility from mumps orchitis, even bilateral orchitis, occurred
infrequently. Oophoritis was reported in approximately 5% of postpubertal females affected
with mumps[17, 18] Mastitis was reported in a few case reports[19, 20] but was also described in an
outbreak in 1956-1957 affecting 31% of postpubertal females. Pancreatitis was reported in 3.5%
of persons infected with mumps in one community during a two year period and was described
in case reports.[21, 22] Permanent sequelae such as paralysis, seizures, cranial nerve palsies, and
hydrocephalus occurred very rarely. Death due to mumps is exceedingly rare, and is primarily
caused by mumps-associated encephalitis. In the United States during 1966-1971, there were
two deaths per 10,000 reported mumps cases.
Post-vaccine era complications
Results from a recent outbreak showed that complications are lower in vaccinated case-patients
compared to unvaccinated case-patients; however, in another recent outbreak, vaccination
status was not significantly associated with complications. Among vaccinated persons, severe
complications of mumps are uncommon but occur more frequently among adults than children.
In recent U.S. outbreaks in 2006 and 2009-2010, rates of orchitis among postpubertal males
have ranged from 3.3% to 10%;[25-27] among postpubertal females, mastitis rates have ranged from <1% to 1%[25-27] and oophoritis rates have ranged from <1% to 1%.[25-27] Among all persons
infected with mumps, reported rates of pancreatitis, deafness, meningitis, and encephalitis were
all <1%.[25-27] No mumps-related deaths have been reported in recent U.S. outbreaks.
Mumps during pregnancy
An association between maternal mumps infection during the first trimester of pregnancy and
an increase in the rate of spontaneous abortion or intrauterine fetal death has been reported in a
large prospective controlled cohort study, but this association was not found in another study.
One study with methodological flaws showed that congenital malformations may occur from
mumps during pregnancy, but because the author did not compare rates with infants born to
women not affected with mumps, these findings must be interpreted with caution; other papers
have not reported similar findings.[4, 31]
Although mumps virus has been isolated from seven days before, through 11-14 days after
parotitis onset,[7, 32, 33] the highest percentage of positive isolations and the highest virus loads
occur closest to parotitis onset and decrease rapidly thereafter. Mumps is therefore most
infectious in the several days before and after parotitis onset. Most transmission likely occurs
before and within five days of parotitis onset. Transmission also likely occurs from persons
with asymptomatic infections and from persons with prodromal symptoms. In 2008, the
period of isolation for mumps patients was changed from nine days to five days.[32, 33] The
recommended period for contact tracing for mumps is two days before through five days after
Other etiologies of parotitis
Not all cases of parotitis—especially sporadic ones—are due to mumps infection. Parotitis
can be caused by parainfluenza virus types 1 and 3, Epstein Barr virus, influenza A virus,
Coxsackie A virus, echovirus, lymphocytic choriomeningitis virus, human immunodeficiency
virus, and noninfectious causes such as drugs, tumors, immunologic diseases, and obstruction
of the salivary duct. However, other causes do not produce parotitis on an epidemic scale.[35, 36]
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Mumps vaccine was licensed in the United States in 1967. The Advisory Committee on
Immunization Practices (ACIP) made an official recommendation for one dose of mumps
vaccine for all children at any age after 12 months in 1977. In 1989, children began receiving
two doses of mumps vaccine because of the implementation of a two-dose measles vaccination
policy using the combined measles, mumps, and rubella vaccine (MMR) vaccine. In 2006, a
two-dose mumps vaccine policy was recommended for school-aged children, students at post
high school educational institutions, healthcare personnel, and international travelers.
Following mumps vaccine licensure, reported mumps decreased steadily from more than
152,000 cases reported in 1968 to 2,982 in 1985. During 1986-1987, a resurgence occurred
with more than 20,000 reported mumps cases. The primary cause of this resurgence was low
vaccination levels among adolescents and young adults. In the late 1980s and early 1990s,
outbreaks were reported among primary and secondary school children who had previously
received one dose of mumps-containing vaccine.[41, 42] By 2003, only 231 mumps cases were
reported, the lowest annual number since reporting began. However, in 2006, another
resurgence occurred, with 6,584 reported cases. The incidence was highest among persons
aged 18-24 years, many of whom were college students. Approximately 63% of all casepatients
with known vaccination status in the main outbreak states had received two doses of
MMR vaccine. In 2007 and 2008, the number of annual cases declined to 800 and 454 cases,
Between June 28, 2009, and June 27, 2010, another large outbreak (3,502 mumps cases)
occurred in Orthodox Jewish communities in the Northeast. The source case was an 11-year-old
U.S. resident with a history of two doses of MMR vaccine who developed parotitis while attending a summer camp in New York after traveling to the United Kingdom. The median age
of persons with mumps was 15 years (range: 3 months to 90 years), 2,479 (71%) were male, and
of the 2,519 (72%) for whom vaccination status was reported, 76% had received two doses, 14%
had received one dose, and 10% had received no doses.
From December 9, 2009, through December 31, 2010, the U.S. Territory of Guam also
experienced an outbreak, with 505 mumps cases reported; 48% of cases were male, and the
median age was 12 years with a range of 2 months to 79 years. Of the 287 school-aged
children aged 6-18 years with reported mumps, 270 (94%) had received at least two doses
of MMR vaccine, 8 (3%) had received one dose, 2 (1%) were unvaccinated, and 7 (2%) had
unknown vaccination status. Two-dose MMR vaccine coverage in the most highly affected
schools ranged from 99.3%-100%.
In the Northeast and Guam mumps outbreaks, third doses of MMR vaccine were administered
under Institutional Review Board protocols to the most affected populations.[27, 43] In both studies,
there were declines in attack rates that were more pronounced in the age groups targeted for
the intervention, but due to the late timing of the intervention and other factors, the results
are inconclusive as to whether the decrease was due to the intervention. Other locations that
were experiencing mumps outbreaks during the same time frame among similar populations
also showed a decline in attack rates without the third dose intervention (New York City,
unpublished data). There is currently no recommendation for a third dose of mumps-containing
vaccine for mumps outbreaks in highly vaccinated populations, but ACIP is considering a
permissive recommendation for such situations. Catch-up vaccination efforts to ensure that
populations at risk are up to date with the recommended number of vaccine doses, as well
as reducing opportunities for close contact, remain the recommended strategies for mumps
Cases of mumps will continue to be imported into the United States as long as mumps continues
to be endemic globally. Mumps vaccine is routinely used in 61% of countries in the world.
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Disease Reduction Goals
The 338 reported cases of mumps in 2000 met the Healthy People 2000 reduction goal of fewer
than 500 cases. Subsequently, a goal of elimination of indigenous mumps by the year 2010
was made. However, major resurgences in mumps during 2006, 2009, and 2010 highlighted
the challenges of obtaining this goal with currently available vaccines and the existing
vaccination policy and resulted in re-evaluation of the mumps program goal in the U.S. Mumps
is endemic throughout the world, and achieving elimination was considered difficult in the
context of ongoing mumps virus importations and the current two-dose vaccination program.
Subsequently, the Healthy People 2020 goal for mumps is a disease reduction goal (i.e., to have
fewer than 500 reported cases of mumps annually), rather than an elimination goal.
Live attenuated mumps virus vaccine is incorporated into combined MMR vaccine. Monovalent
mumps vaccine is no longer produced in the United States. For prevention of mumps, two doses
of MMR vaccine are recommended routinely for children with the first dose at 12-15 months of
age and the second dose at 4-6 years of age (school entry).
For prevention of mumps, two doses of MMR vaccine are also recommended for adults at
high risk, including international travelers, college and other post high school students, and
healthcare personnel born during or after 1957.[39, 47] All other adults born during or after 1957
without other evidence of mumps immunity should be vaccinated with one dose of MMR
vaccine[39, 47] Vaccination recommendations for an outbreak setting are discussed in the "Outbreak
Control" section later in this chapter.
The mumps vaccine component of the MMR vaccine has a lower effectiveness compared to the
measles and rubella components. Mumps vaccine effectiveness has been estimated at a median
of 78% (range: 49%−91%) for one dose1, [42, 48-51] and a median of 88% (range: 66%−95%) for two
Mumps vaccine can also be administered as a combined vaccine with measles, rubella, and
varicella vaccines (MMRV); however, MMRV vaccine is currently available in limited
supply. MMRV vaccine can be used for children aged 12 months through 12 years who
need a first dose of MMR and varicella vaccine, or who need a second dose of MMR and
either a first or second dose (as indicated) of varicella vaccine.
For the first dose of measles, mumps, rubella, and varicella vaccines at age 12-47 months,
either MMR vaccine and varicella vaccine or MMRV vaccine may be used. Providers
who are considering administering MMRV vaccine should discuss the benefits and risks
of both vaccination options with the parents or caregivers. Compared with use of MMR
and varicella vaccines given separately at the same visit, use of MMRV vaccine results
in one fewer injection but is associated with a higher risk for fever and febrile seizures 5
through 12 days after the first dose among children aged 12 through 23 months (about one
extra febrile seizure for every 2,300-2,600 MMRV vaccine doses). Unless the parent or
caregiver expresses a preference for MMRV vaccine, CDC recommends that MMR vaccine
and varicella vaccine should be administered for the first dose in this age group. For the
first dose of measles, mumps, rubella, and varicella vaccines at ages 48 months and older
and for dose two at any age (15 months through 12 years), use of MMRV vaccine generally
is preferred over separate injections of its equivalent component vaccines (i.e., MMR and
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Presumptive Evidence of Mumps Immunity
According to ACIP recommendations published in 2006, acceptable presumptive evidence
of mumps immunity includes at least one of the following:
written documentation of receipt of one or more doses of a mumps-containing vaccine
administered on or after the first birthday for preschool-aged children and adults not
at high risk, and two doses of mumps-containing vaccine for school-aged children and
adults at high risk (i.e., healthcare personnel, international travelers, and students at
post high school educational institutions);
- laboratory evidence of immunity;
- birth before 1957; or
- documentation of physician-diagnosed mumps.
Persons who do not meet the above criteria are considered susceptible. Healthcare settings
have slightly different criteria for acceptable presumptive evidence of immunity, and these
criteria are detailed in the 'Healthcare Personnel: Presumptive Evidence of Immunity'
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The following case definition for mumps was updated and approved by the Council of State
and Territorial Epidemiologists (CSTE) in 2011.
Disease specific data elements:
Disease-specific data elements to be included in the initial report are listed below.
- parotitis or swelling of sublingual or submandibular salivary glands for two or more days
- onset date of symptoms
- mumps-associated complications (describe)
- contact (or in a chain of contacts) of a laboratory-confirmed mumps case
- contact of a person with parotitis
- contact of a person with a mumps-associated complication
- member of a risk group defined by public health authorities during an outbreak
- return from international travel within 25 days of symptom onset
- Travel location
- Date of return to U.S.
- number of doses of mumps-containing vaccine received
- date of all doses of mumps-containing vaccine received
Case definition for case classification
- parotitis, acute salivary gland swelling, orchitis, or oophoritis unexplained by another more
- a positive lab result with no mumps clinical symptoms (with or without epidemiological
linkage to a confirmed or probable case).
- Acute parotitis or other salivary gland swelling lasting at least 2 days, or orchitis or oophoritis
unexplained by another more likely diagnosis, in:
- a person with a positive test for serum anti-mumps IgM antibody, or
- a person with epidemiologic linkage to another probable or confirmed case or linkage to a
group/community defined by public health during an outbreak of mumps.
- A positive mumps laboratory confirmation for mumps virus with RT-PCR or culture in a
patient with an acute illness characterized by any of the following:
- Acute parotitis or other salivary gland swelling, lasting at least 2 days
- Aseptic meningitis
- Hearing loss
Case classification for import status
Internationally imported case: An internationally imported case is defined as a case in which
mumps results from exposure to mumps virus outside the United States as evidenced by at least
some of the exposure period (12-25 days before onset of parotitis or other mumps-associated
complications) occurring outside the United States and the onset of parotitis or other mumpsassociated
complications within 25 days of entering the United States and no known exposure
to mumps in the U.S. during that time. All other cases are considered U.S.-acquired cases.
U.S.-acquired case: A U.S.-acquired case is defined as a case in which the patient had not been
outside the United States during the 25 days before onset of parotitis or other mumps-associated
complications or was known to have been exposed to mumps within the United States.
U.S.-acquired cases are sub-classified into four mutually exclusive groups:
- Import-linked case: Any case in a chain of transmission that is epidemiologically linked to
an internationally imported case.
- Imported-virus case: A case for which an epidemiologic link to an internationally imported
case was not identified but for which viral genetic evidence indicates an imported mumps
genotype (i.e., a genotype that is not occurring within the United States in a pattern indicative of endemic transmission). An endemic genotype is the genotype of any mumps virus that
occurs in an endemic chain of transmission (i.e., lasting ≥12 months). Any genotype that
is found repeatedly in U.S.-acquired cases should be thoroughly investigated as a potential
endemic genotype, especially if the cases are closely related in time or location.
- Endemic case: A case for which epidemiological or virological evidence indicates an
endemic chain of transmission. Endemic transmission is defined as a chain of mumps virus
transmission continuous for ≥12 months within the United States.
- Unknown source case: A case for which an epidemiological or virological link to
importation or to endemic transmission within the U.S. cannot be established after a thorough
investigation. These cases must be carefully assessed epidemiologically to assure that they
do not represent a sustained U.S.-acquired chain of transmission or an endemic chain of
transmission within the U.S.
Note: Internationally imported, import-linked, and imported-virus cases are considered
collectively to be import-associated cases.
States may also choose to classify cases as "out-of-state-imported" when imported from another
state in the United States. For national reporting, however, cases will be classified as either
internationally imported or U.S.-acquired.
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If mumps is suspected, laboratory testing should be performed. Acute mumps infection can be
detected by the presence of serum mumps IgM, a significant rise in IgG antibody titer in acuteand
convalescent-phase serum specimens, IgG seroconversion, positive mumps virus culture,
or detection of virus by real-time reverse transcriptase polymerase chain reaction (rRT-PCR).
However, in both unvaccinated and vaccinated persons, false positive results can occur because
assays may be affected by other diagnostic entities that cause parotitis. In addition, laboratoryconfirming
the diagnosis of mumps in highly vaccinated populations may be challenging, and
serologic tests should be interpreted with caution because false negative results in vaccinated
persons (i.e., a negative serologic test in a person with true mumps) are common. With previous
contact with mumps virus either through vaccination (particularly with two doses) or natural
infection, serum mumps IgM test results may be negative; IgG test results may be positive
at the initial blood draw; and viral detection in RT-PCR or culture may have low yield if the
buccal swab is collected more than three days after parotitis onset. Therefore, mumps cases
should not be ruled out by negative laboratory results. These challenges are discussed in more
Virus detection (real-time RT-PCR and culture)
Mumps virus can be detected from fluid collected from the parotid duct, other affected salivary
gland ducts, the throat, from urine, and from cerebrospinal fluid (CSF). Parotid duct swabs
yield the best viral sample. This is particularly true when the salivary gland area is massaged
approximately 30 seconds prior to swabbing the buccal/parotid duct, so that the specimen
contains the secretions from the parotid or other salivary duct glands. Efforts should be made
to obtain the specimen as soon as possible after onset of parotitis or meningitis. Clinical
specimens should ideally be obtained within three days and not more than eight days after
Successful virus isolation should always be confirmed by immunofluorescence with a mumpsspecific
monoclonal antibody or by molecular techniques. Molecular techniques such as
real-time RT-PCR can also be used to detect mumps RNA directly for mumps confirmation in
appropriately collected specimens.
Urine samples are less likely than oral specimens to contain sufficient virus copies or virusinfected
cells for culture or detection by molecular methods, and therefore are not preferred.
Molecular typing is recommended because it provides important epidemiologic information.
Molecular epidemiologic surveillance, (i.e., virus genotyping) allows the building of a sequence
database that will help track transmission pathways of mumps strains circulating in the United States. In addition, genotyping methods are available to distinguish wild-type mumps virus
from vaccine virus.
- Unvaccinated persons: Virus may be isolated from the buccal mucosa until 11-14 days after
salivary enlargement; however, viral isolation is most likely to be successful just prior to and
within the first three days of parotitis onset.
- Vaccinated persons: In order to optimize virus yield, emphasis should be placed on obtaining
mumps clinical specimens from buccal mucosa within 1 to 3 days after onset of symptoms
In the case of specimens for virus culture or PCR assay, immediately place specimens in a cold
storage container and transport to the laboratory.
The serologic tests available for laboratory confirmation of mumps acute infection and
confirmation of previous exposure to mumps vary among laboratories. The State health
department can provide guidance regarding available laboratory services. At the direction of
the State health department, healthcare providers and State and local health departments may
send serum specimens from suspected mumps cases to the CDC Measles, Mumps, Rubella,
and Herpes Laboratory Branch for IgM detection by EIA. See "Specimen collection and
management" section below.
- At the initial visit, a serum specimen should be obtained to test for mumps IgM antibodies.
- If the acute-phase specimen is positive for IgM, a second specimen is not necessary.
- A second negative IgM does not rule out mumps unless the IgG result is also negative.
- Paired serum specimens may also be used to demonstrate seroconversion from negative
to positive from acute to convalescent, which is considered a positive diagnostic result for
mumps. In unvaccinated individuals, a four-fold increase in IgG titers is also considered a
positive diagnostic result for mumps, but these are rarely done.
Tests for IgM antibody
Enzyme immunoassay (EIA): a highly specific test for diagnosing acute mumps infection. The
use of the IgM capture EIA is preferred over the Immunofluorescence assay (IFA).
Immunofluorescence assay (IFA): a test that is relatively inexpensive and simple, but the IFA
format is particularly susceptible to interference by high levels of mumps-specific IgG. Reading
the test requires considerable skill and experience since this nonspecific staining may cause
false positive readings if the serum is not treated with an agent to remove human IgG antibody.
Note: Commercially available EIA kits and IFA antibody assays for detection of mumps
IgM are not currently FDA-approved. Therefore, each laboratory must validate these tests
Serum collection and timing of the mumps IgM response
- Unvaccinated persons: IgM antibody is detectable within 5 days after onset of symptoms,
reaches a maximum level about a week after onset, and remains elevated for several weeks or
months.[57, 58] If an acute-phase serum sample collected ≤3 days after parotitis onset is negative
for IgM, testing a second sample collected 5-7 days after symptom onset is recommended
since the IgM response may require more time to develop.
- Vaccinated persons: Patients that mount a secondary immune response to mumps, as seen
in most previously vaccinated persons, may not have an IgM response or it may be transient
and not detected depending on the timing of specimen collection. Because of this, a high
number of false negative results may occur in previously vaccinated individuals. False
positive IgM results may also occur and appear to be more prevalent with certain IgM test
formats, such as the IFA. There is some evidence that serum collected ≥10 days after parotitis
onset may improve the ability to detect IgM among persons who have received one or two
doses of MMR vaccine (CDC, unpublished data). However, persons with a history of
mumps vaccination may not have detectable mumps IgM antibody regardless of the timing of
Tests for IgG antibody
Tests for IgG antibody may be used for mumps diagnosis or for testing mumps immunity.
A variety of tests for IgG antibodies to mumps are available and include EIA, IFA, and plaque
reduction neutralization. The specific criteria for documenting an increase in titer depend
on the test.
Diagnosis of Mumps with IgG
IgG testing for laboratory confirmation of mumps requires the demonstration of seroconversion
from negative to positive by EIA or a four-fold rise in the titer of antibody against mumps as
measured in plaque-reduction neutralization assays or similar quantitative assays. The tests for
IgG antibody should be conducted on both acute- and convalescent-phase specimens at the same
time. The same type of test should be used on both specimens. EIA values are not titers, and
increases in EIA values do not directly correspond to titer rises.
- Unvaccinated persons: In unvaccinated persons, IgG antibody increases rapidly after onset
of symptoms and is long lasting.
- Vaccinated persons: In vaccinated persons, the IgG may already be quite elevated in the
acute-phase blood sample which frequently prevents detection of a four-fold rise in IgG titer
in the convalescent serum specimen.
Testing Mumps Immunity with IgG
A single serum sample tested for mumps-specific IgG is not useful for diagnosing acute mumps
infections. The presence of mumps-specific IgG, as detected using a serologic assay (EIA or
IFA), is considered evidence of mumps immunity but does not necessarily predict the presence
of neutralizing antibodies or protection from mumps disease.
Specimen collection and management
Specific instructions for specimen collection and shipping may be obtained from the CDC
mumps website or by contacting
the CDC MMR and Herpes Virus Laboratory Branch at 404-639-1156 or 404-639-3512.
Specimens for virus isolation and genotyping should be sent to CDC as directed by the State
For additional information on use of laboratory testing for surveillance of vaccine-preventable
diseases, see Chapter 22, "Laboratory Support for the Surveillance of Vaccine-Preventable
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Each state and U.S. territory has regulations or laws governing the reporting of diseases and
conditions of public health importance.61 These regulations and laws list the diseases that
are to be reported and describe those persons or groups responsible for reporting, such as
healthcare providers, hospitals, schools, laboratories, daycare and childcare facilities, and other
institutions. Persons reporting these conditions should contact their State health department for
state-specific reporting requirements.
Reporting to CDC
A provisional report of all probable and confirmed mumps cases should be sent by the State
health department to CDC via the National Notifiable Diseases Surveillance System (NNDSS).
Electronic reporting of case records should not be delayed because of incomplete information
or lack of confirmation. Following completion of case investigations, case records should be
updated with any new information and resubmitted to CDC. Final laboratory results may not be
available for the initial report but should be submitted via NNDSS when available.
Information to collect
The following data should be collected in the course of the case investigation. Additional
information may be collected at the direction of the State health department.
- Demographic information
- Date of birth
- Country of birth
- Length of time in United States
- Reporting source
- Earliest date reported
- Date of illness onset (note: this may be earlier than parotitis onset due to prodromal
- Parotitis or other salivary gland involvement (pain, tenderness, swelling)
- Date of parotitis (or other salivary gland swelling) onset
- Duration of parotitis (or other salivary gland swelling)
- Other symptoms (e.g., headache, anorexia, fatigue, fever, body aches, stiff neck, difficulty in swallowing, nasal congestion, cough, earache, sore throat, nausea, abdominal pain)
- Deafness (transient or permanent; unilateral or bilateral)
- Orchitis (unilateral or bilateral)
- Hospitalization, reason/association to mumps, duration of stay
- Outcome (patient survived or died)
- Date of death
- Postmortem examination results
- Death certificate diagnoses
- Medications given
- Duration person was on each medication
- Serology (IgM, IgG)
- Virus detection (PCR, culture)
- Specimen collection date(s)
- Vaccine information
- Number of doses of vaccine given
- Type of vaccine administered (i.e., MMR, MMRV, or single antigen mumps vaccine)
- Dates of mumps vaccination for each dose
- Manufacturer of vaccine
- Vaccine lot number
- If not vaccinated, reason
- Epidemiologic linkages
- Transmission setting (e.g., college, school, doctor’s office)
- Import status (e.g., internationally imported or U.S.-acquired). See Case Classification section above.
- Location of exposure (country, if international import; state, if out-of-state import)
- Travel history
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The Mumps Surveillance Worksheet (Appendix 10)[2 pages] may be used as a guideline to collect case information during a case investigation; the details are discussed below.
Identification of suspected or confirmed cases of mumps is important in the initiation of control
measures to prevent the spread of the disease among persons who do not have presumptive
evidence of immunity. Once a sporadic case has been identified, several factors should be
taken into consideration before initiating a public health response, such as epidemiological risk
factors, vaccination status, and other etiologies. However, in transmission settings with high
risk, such as households, schools, and camps, health departments may want to be a little more
aggressive. In these settings, health departments should consider conducting case investigations
and assessing immune status of close contacts before laboratory results are known or before
additional cases are identified. Nonetheless, control measures are unlikely to be implemented
until either the laboratory results are back or until at least two infected persons have a confirmed
Establishing a diagnosis of mumps
Clinical diagnosis of mumps may be unreliable. Cases of suspected mumps should be laboratory
confirmed; however, negative laboratory results among vaccinated persons do not necessarily
rule out the diagnosis of mumps, particularly if there is an outbreak of parotitis.
Efforts should be made to obtain clinical specimens (buccal cavity/parotid duct fluids, throat
swabs, urine, or CSF) for viral isolation for all sporadic cases and at least some cases in each
outbreak at the time of the initial investigation.
Obtaining accurate, complete immunization histories
Mumps case investigations should include complete immunization histories that are verified
by documentation of administration of all doses. Verbal history of receipt of mumps vaccine is
not considered adequate proof of vaccination. Some case-patients or their caregivers may have
personal copies of immunization records available that include dates of administration; these
are acceptable for reporting purposes.
Identifying the source of infection
Efforts should be made to identify the source of infection for every confirmed case of mumps
(i.e., case-patients should be asked about contact with other known patients). However, this is
not always possible, especially with sporadic cases, and this should not occur at the expense
of higher public health priorities. If it can be determined when and where transmission likely
occurred, investigative efforts should be directed to these locations.
Assessing potential transmission and identifying contacts
The potential for further transmission should be assessed. Contacts of the case-patient during
the two days prior through five days after onset of parotitis should be identified, assessed for
immunity, offered vaccine as appropriate, and educated about signs and symptoms.
CDC recommends a five-day period after onset of parotitis for: 1) isolation of persons with
mumps in the community and for 2) use of droplet precautions, in addition to standard
precautions in healthcare settings.
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Importance of surveillance
Information obtained through surveillance is used to follow disease trends in the population,
to assess progress towards disease reduction goals, and to characterize populations requiring
additional disease control measures.
Monitoring surveillance indicators
Regular monitoring of surveillance indicators can help identify specific areas of the surveillance
and reporting system that need improvement. The following indicators should be monitored.
- The proportion of confirmed cases reported to NNDSS with complete information
(e.g., date of birth, onset date, clinical case definition, hospitalization, laboratory testing,
vaccine history, date reported to health department, transmission setting, outbreak-related,
and epidemiologic linkage)
- The interval between date of symptom onset and date of public health notification
- The proportion of cases that are laboratory confirmed
- The proportion of cases that have an imported source
The activities listed below can help increase the number of suspected mumps cases that are
reported and improve the comprehensiveness and quality of reports that are received. Additional
guidelines for enhancing surveillance are given in Chapter 19, "Enhancing Surveillance."
In the event of an outbreak, surveillance should be enhanced by promoting awareness in the
public affected by the outbreak and healthcare personnel. Healthcare personnel should be aware
that mumps outbreaks have occurred in highly vaccinated populations in high transmission
settings, including school settings (e.g., elementary school, middle school, high school, and
college students). Therefore, mumps should not be ruled out on the assumption that individuals
have evidence of mumps immunity because of vaccination.
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A mumps outbreak is defined as three or more cases linked by time and place. In recent years,
mumps outbreaks have occurred in highly vaccinated populations in high transmission settings,
including elementary, middle, and high schools, colleges, and camps. Especially in these
settings, rapid detection and investigation of cases, and implementation of control measures
may reduce the magnitude of outbreaks. The following are general guidelines for an outbreak
Collecting tracking information
During an outbreak, a line listing of cases on a spreadsheet allows for quick identification of
known and unknown data and ensures that complete case investigations are done.
Identifying the population affected by the outbreak
During an outbreak, every suspected case should be investigated thoroughly, as described above.
In very large outbreaks, it may not be possible to thoroughly investigate each reported case.
Based on the findings of individual case investigations, the population affected by the outbreak
should be characterized in terms of:
- person (who is becoming infected with mumps, what is their vaccination status),
- place (where are the cases), and
- time (when did the outbreak start, and is it still going on).
Obtaining accurate and complete immunization histories
Vaccination histories may be obtained from schools (generally available for children attending
licensed childcare centers or kindergarten through high school, as well as many universities),
medical providers, or immunization records provided by the case-patient. Immunization
registries, if available, can also readily provide vaccination histories.
Identifying contacts (e.g., household, school/college, and other close contacts) and following
up with persons without evidence of mumps immunity may reveal previously undiagnosed and
Enhancing surveillance for mumps
Local or State health departments should contact healthcare providers in outbreak areas to
inform them of the outbreak and request reporting of any suspected cases. During outbreaks,
active surveillance for mumps should be conducted for every confirmed and probable mumps
case. Active surveillance should be maintained for at least two incubation periods (50 days)
following parotitis onset in the last case. Two incubation periods allow for the identification of
transmission from subclinical infections or unrecognized cases. Previously unreported cases
may be identified by reviewing laboratory records.
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Initial preparation for control activities may need to be started before laboratory results are
known, but are unlikely to be implemented until either the laboratory results are back or until
at least two infected persons have a confirmed epidemiological link.
The main strategy for controlling a mumps outbreak is to define the population(s) at risk and
transmission setting(s), and to rapidly identify and vaccinate persons without presumptive
evidence of immunity; or, if a contraindication exists, to exclude persons without presumptive
evidence of immunity from the setting to prevent exposure and transmission.
Mumps-containing vaccine should be administered to persons without evidence of immunity
and everyone should be brought up to date with age appropriate vaccination (one or two doses).
Although mumps-containing vaccination has not been shown to be effective in preventing
mumps in persons already infected, it will prevent infection in those persons who are not
yet exposed or infected. If persons without evidence of immunity can be vaccinated early
in the course of an outbreak, they can be protected prior to exposure. However, because of
the long incubation period for mumps, cases are expected to continue to occur for at least
25 days among newly vaccinated persons who may have been infected before vaccination.
As with all vaccines, some individuals will not develop protective immunity after receipt of
mumps vaccine. Depending on the epidemiology of the outbreak (e.g., the age groups and/or
institutions involved), a second dose of mumps-containing vaccine should be considered for
children aged 1-4 years and adults who have received one dose previously.
To assist with control of mumps outbreaks in schools and colleges, students with zero doses
of MMR vaccine and with no other evidence of mumps immunity should be excluded from
schools/colleges affected by a mumps outbreak or other schools that are unaffected but deemed
by local public health authorities to be at risk for transmission of disease. Excluded students
can be readmitted immediately after they are vaccinated. Students who have a history of one
dose of MMR vaccination should receive their second vaccine dose and be allowed to remain
in school. Students who have been exempted from mumps vaccination for medical, religious, or other reasons should be excluded until the 26th day after the onset of parotitis in the last
person with mumps in the affected school.
Currently, data are insufficient to recommend for or against the use of a third dose of MMR vaccine for mumps outbreak control. CDC has issued guidance for considerations for use of a third dose in specifically identified target populations along with criteria for public health departments to consider for decision making.
During mumps outbreaks, public health authorities may administer a third dose of MMR vaccine for specifically identified target populations.
Criteria to consider prior to administering a third dose in a target population for mumps outbreak control include:
- high two-dose vaccination coverage (i.e., vaccination coverage >90%);
- intense exposure settings likely to facilitate transmission (e.g., schools, colleges, correctional facilities, congregate living facilities) or healthcare settings;
- high attack rates (i.e., >5 cases per 1,000 population); and evidence of ongoing transmission for at least two weeks in the target population (i.e., population with the high attack rates)
Additional data on the effectiveness and impact of a third dose of MMR vaccine for mumps outbreak control are needed to guide control strategies in future outbreaks. Authorities who decide to administer a third dose as part of mumps outbreak control are encouraged to collect data to evaluate the impact of the intervention. The following data should be collected:
- incidence of mumps in target population (before and after the intervention, by vaccination status),
- incidence of adverse events following vaccination with a third dose, and
- costs associated with the intervention (vaccine, personnel)
Catch-up vaccination efforts to ensure that populations
at risk are up to date with the recommended number of vaccine doses, as well as reducing
opportunities for close contact, remain the recommended strategies for mumps outbreak control.
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Prevention and control strategies in healthcare settings
Prevention and control strategies should be applied in all healthcare settings, including
outpatient and long-term care facilities. These measures include:
- assessment of presumptive evidence of immunity of healthcare personnel, including
documented administration of two doses of live mumps virus vaccine, laboratory evidence
of immunity or laboratory confirmation of disease, or birth before 1957 (refer to next
section, "Healthcare personnel presumptive evidence of immunity" for footnotes),
- vaccination of those without evidence of immunity,
- exclusion of healthcare personnel with active mumps illness, as well as healthcare
personnel who do not have presumptive evidence of immunity who are exposed to
persons with mumps,
- isolation of patients in whom mumps is suspected, and
- implementation of droplet precautions, in addition to standard precautions.
An effective vaccination program is the best approach to prevent healthcare-associated mumps
transmission. Healthcare Infection Control Practices Advisory Committee (HICPAC) and CDC
have recommended that secure, preferably computerized, systems should be used to manage
vaccination records for healthcare personnel so records can be easily retrieved as needed.
Facilities are also encouraged to review employee evidence of immunity status for mumps and
other vaccine preventable infections. Healthcare facilities should provide MMR vaccine to all
personnel without evidence of mumps immunity at no charge.
Healthcare personnel: presumptive evidence of immunity
The presumptive evidence of immunity criteria for healthcare personnel differs slightly from the
criteria for community settings. The following criteria should be followed to assess presumptive
evidence of immunity among healthcare personnel.
- Written documentation of vaccination with two doses of live mumps or MMR vaccine
administered at least 28 days apart*
- Laboratory evidence of immunity†
- Laboratory confirmation of disease
- Birth before 1957‡§¶#
In the event that a nosocomial outbreak occurs, healthcare facilities should have a plan in place
for the implementation of the two-dose recommendation for all healthcare personnel, including
those who were born before 1957 and lack laboratory evidence of immunity or laboratory
confirmation of disease. Healthcare facilities may choose to proceed with appropriate
assessment and vaccination of personnel born before 1957 before an outbreak occurs.
Although there are no data that correlate levels of serum antibody with protection from disease,
presence of mumps-specific IgG antibodies is considered evidence of mumps immunity. For
healthcare personnel who do not have adequate presumptive evidence of mumps immunity,
prevaccination antibody screening before MMR vaccination is not necessary.
Results of serum antibody tests in vaccinated persons are difficult to interpret. In vaccinated
persons, antibody levels are often lower than following natural infection, and commercially
available tests may not detect such low levels of antibody. As a result, postvaccination
serologic testing to verify an immune response to MMR or its component vaccines is not
recommended. There are no data on the effect of additional (greater than two) doses of mumps
vaccine on antibody levels or protection from disease.
Healthcare personnel exclusion
Healthcare personnel with active mumps illness and those who lack evidence of immunity
and have had unprotected exposures to mumps should be excluded from work from the 12th
day after the first unprotected exposure to mumps through the 25th day after the last exposure.
Unprotected exposures are defined as being within three feet of a patient with a diagnosis of
mumps without the use of proper personal protective equipment. Irrespective of their immune
status, all exposed healthcare personnel should report any signs or symptoms of illness during
the incubation period, from 12 through 25 days after exposure.
Management of healthcare personnel with illness due to mumps
- A diagnosis of mumps should be considered in exposed healthcare personnel who develop
non-specific respiratory infection symptoms during the incubation period after unprotected
exposures to mumps, even in the absence of parotitis.
- Healthcare personnel with mumps illness should be excluded for five days after the onset of
Management of healthcare personnel who are exposed to persons with mumps
For healthcare personnel who do not have acceptable presumptive evidence of immunity
- Healthcare personnel without evidence of immunity should be excluded from the 12th day
after the first unprotected exposure to mumps through the 25th day after the last exposure.
- Previously unvaccinated healthcare personnel who receive a first dose of vaccine after an
exposure are considered non-immune and should be excluded from the 12th day after the
first exposure to mumps through the 25th day after the last exposure. The mumps vaccine
cannot be used to prevent the development of mumps after exposure.
For healthcare personnel with partial vaccination
- Healthcare personnel who had been previously vaccinated for mumps, but received only one
dose of mumps vaccine may continue working following an unprotected exposure to mumps.
Such personnel should receive a second dose as soon as possible, but no sooner than 28 days
after the first dose. They should be educated about symptoms of mumps, including nonspecific
presentations, and should notify occupational health if they develop these symptoms.
For healthcare personnel who have presumptive evidence of immunity
- Healthcare personnel with evidence of immunity do not need to be excluded from work
following an unprotected exposure. However, two doses of MMR vaccine do not provide
100% protection from mumps. Some vaccinated personnel may remain at risk for mumps.
Therefore, healthcare personnel should be educated about symptoms of mumps, including
nonspecific presentations, and should notify occupational health if they develop these
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