Disease Description Questions:

What causes mumps?

Mumps is a viral illness caused by a paramyxovirus of the genus Rubulavirus.

What are the clinical manifestations of mumps?

The classic symptoms of mumps include parotitis in about 50% either unilateral bilateral, which develops an average of 16 to 18 days after exposure. Swelling can also be seen in the submandibular and sublingual gland in a small percentage. Nonspecific symptoms including myalgia, anorexia, malaise, headache, and low-grade fever may precede parotitis by several days. As many as 40%–50% of mumps infections are associated with nonspecific or primarily respiratory symptoms, particularly among children less than 5 years of age. Only 30-40% of mumps infections produce typical acute parotitis. In 15-20% of infections, cases are asymptomatic.

Are there other causes of parotitis?

Yes, but only mumps causes epidemic parotitis. Parotitis can also be caused by parainfluenza virus types 1 and 3, influenza A virus, Coxsackie A virus, echovirus, lymphocytic choriomeningitis virus, human immunodeficiency virus, and other non-infectious causes such as drugs, tumors, immunologic diseases, and obstruction of the salivary duct.

What is the incubation period and period of infectiousness?

The average incubation period for mumps is 16-18 days, with a range of 12–25 days. Fever may persist for 3–4 days and parotitis, when present, usually lasts 7–10 days. Persons with mumps are usually considered infectious from 3 days before until 9 days after onset of parotitis.

How is the mumps virus transmitted?

The mumps virus replicates in the upper respiratory tract and is spread through direct contact with respiratory secretions or salvia or through fomites.

What about mumps complications?

Severe complications of mumps are rare. However, mumps can cause acquired sensorineural hearing loss in children; incidence is estimated at 1 in 20,000 cases. Mumps-associated encephalitis occurs in < 2 per 100,000 cases and approximately 1% of encephalitis cases are fatal.

Some complications of mumps are known to occur more frequently among adults than among children. Adults have a higher risk for mumps meningoencephalitis than children. In addition, orchitis occurs in up to 30-40% of cases in post pubertal males. Although it is frequently bilateral, it rarely causes sterility. Mastitis has been reported in as many as 31% of female patients older than 15 years who have mumps. Other rare complications of mumps are oophoritis and pancreatitis. Aseptic meningitis occurs in 10% of cases and is associated with a good prognosis. Although mumps infection in the first trimester of pregnancy may result in fetal loss, there is no evidence that mumps during pregnancy causes congenital malformations.

Long-term effects of mumps?

Permanent sequelae such as paralysis, seizures, cranial nerve palsies, aqueductal stenosis, and hydrocephalus are rare, as are deaths due to mumps.

What is a case definition for mumps?

The following case definition for mumps was approved by the Council of State and Territorial Epidemiologists (CSTE) in 1999.

Clinical case definition
An illness with acute onset of unilateral or bilateral tender, self-limited swelling of the parotid or other salivary gland, lasting 2 or more days, and without other apparent cause.

Laboratory criteria for diagnosis

• Positive serologic test for mumps immunoglobulin M (IgM) antibody, or
• A four-fold rise between acute- and convalescent -phase titers in serum mumps immunoglobulin G (IgG) antibody level by any standard serologic assay, or
• Isolation of mumps virus from clinical specimen, or
• Detection of mumps viral RNA by reverse transcription polymerase chain reaction (RT­PCR)

Case classification

Probable: A case that meets the clinical case definition, has noncontributory or no serologic or virologic testing, and is not epidemiologically linked to a confirmed or probable case.

Confirmed: A case that is laboratory confirmed or that meets the clinical case definition and is epidemiologically linked to a confirmed or probable case. A laboratory-confirmed case does not need to meet the clinical case definition.

Comment. False-positive IgM results by immunofluorescent antibody assays have been reported.

For more information, please see the Case investigation and outbreak control of the VPD Surveillance Manual.

Laboratory Questions:

Consult Laboratory Specimen Collection and Management for specific answers to laboratory questions and Laboratory Testing for Mumps Infection. ADDED second link May 22

Case Reporting Questions:

What information on cases do I need to collect?

Please see the Reporting mumps page adopted from the VPD Surveillance Manual, Mumps Chapter, Reporting section, page 5.

Where do I report a case?

Report cases to your local or state health department.

Vaccine Questions:

Who should receive MMR vaccine?

The principal strategy to prevent mumps is to achieve and maintain high immunization levels. The Advisory Committee on Immunization Practices (ACIP) recommends that all preschool aged children 12 months of age and older receive 1 dose of measles-mumps-rubella vaccine (MMR) and all school-aged children receive two doses of MMR, and to ensure that all adults have evidence of immunity against mumps. As noted below, two doses of mumps vaccine are more effective than a single dose. Consequently, during outbreaks and for at-risk populations, ensuring high vaccination coverage with two doses is encouraged. For example, h ealth care workers may be at increased risk of acquiring mumps and transmitting to patients and thus should receive two doses of MMR vaccine or provide proof of immunity. Since vaccination is the cornerstone of mumps prevention, public and private health entities concerned about spread of mumps in a population can review the vaccination status of populations of interest and work to address gaps in vaccination.

See also MMWR article: Vaccine Use and Strategies for Elimination of Measles, Rubella, and Congenital Rubella Syndrome & Control of Mumps: Recommendations of ACIP      (.pdf)
May 22, 1998 / 47(RR-8);1-57 

How long does it take to develop immunity to mumps after vaccination with MMR?

In one study 86.6% of vaccinees had evidence of mumps seroconversion at 4 weeks after immunization and 93.3% had evidence of seroconversion after 5 weeks. However, seroconverion may not result in immunity. About 80% of persons who have received 1 dose can be considered protected and 90% after 2 doses.

Why might some people born before 1957 need to be vaccinated with MMR?

Live mumps vaccine was not used routinely before 1967. Before the vaccine was introduced, the age-specific incidence of the disease peaked among children aged 5-9 years. Therefore, most persons born before 1957 are likely to have been infected naturally between 1957 and 1977 and may be presumed to be immune, even if they have not had clinically recognizable mumps disease. However, birth before 1957 does not guarantee mumps immunity. Therefore, during mumps outbreaks, MMR vaccination should be considered for persons born before 1957 who may be exposed to mumps and who may be susceptible. Laboratory testing for mumps susceptibility before vaccination is not necessary. (For more information see page 15 of the MMWR article Vaccine Use and Strategies for Elimination of Measles, Rubella, and Congenital Rubella Syndrome & Control of Mumps: Recommendations of ACIP     (.pdf)
May 22, 1998 / 47(RR-8);1-57)

Can health care workers (HCW's) get the MMR vaccine and continue to work?

Yes. There are no reports of transmission of live attenuated measles or mumps viruses from vaccinees to susceptible contacts. For more information see, Prevention & Control of Mumps Among Healthcare Personnel.

Who should not be given MMR vaccine?

Women known to be pregnant should not receive MMR vaccine. Pregnancy should be avoided for four weeks following MMR vaccine. Close contact with a pregnant woman is NOT a contraindication to MMR vaccination of the contact. Breastfeeding is NOT a contraindication to vaccination of either the woman or the breastfeeding child.

MMR is not recommended for those with evidence of severe immunosuppression.

Are there any changes to the childhood vaccination schedule for mumps during an outbreak?

No. Any changes would depend on the epidemiology and age groups affected by an outbreak. Unless otherwise advised, children should be vaccinated according to the vaccination schedule. Preschool-aged children should receive the first dose of MMR vaccine as close to age 12 months as possible (i.e., on or after the first birthday). The second dose of MMR vaccine is recommended when children are aged 4-6 years (i.e., before a child enters kindergarten or first grade). This recommended timing for the second dose of MMR vaccine has been adopted jointly by ACIP, the American Academy of Pediatrics (AAP), and the American Academy of Family Physicians (AAFP). If the outbreak affects the 1-4 year old age group, then the shildren should receive their 2 nd MMR dose now, provided 28 days have passed since receipt of their first dose of MMR. A 2 dose vaccine schedule for measles vaccine administered as MMR was recommended in 1989. In 1998, states were strongly encouraged to take immediate steps to ensure that, by 2001, all children in grades kindergarten through 12 have received two doses of MMR vaccine.

If required, the second MMR dose should be administered as soon as possible, but no sooner than 28 days after the first dose.

If exposed, will the MMR vaccine prevent mumps infection?

Mumps vaccine has not been shown to be effective in preventing mumps in already infected persons.

Should an IgG be drawn after two doses of MMR?

No. It is not necessary to draw an IgG after vaccines to confirm immunity.

Can the single mumps vaccine be used to vaccinate?

Yes, however the preferred vaccine is the MMR combination vaccine which also protects against measles and rubella. The single mumps vaccine is no longer widely available.

Are there special vaccination recommendations for colleges and other post-high school education institutions?

Risks for transmission of measles, rubella, and mumps at post-high school educational institutions can be high because these institutions bring together large concentrations of persons who may be susceptible to these diseases. Therefore, colleges, universities, technical and vocational schools, and other institutions for post-high school education should require that all undergraduate and graduate students have received two doses of MMR vaccine or have other acceptable evidence of measles, rubella, and mumps immunity before enrollment.

Students who do not have documentation of MMR vaccination or other acceptable evidence of immunity at the time of enrollment should be admitted to classes only after receiving the first dose of MMR vaccine. These students should be administered a second dose of MMR vaccine 1 month (i.e., at least 28 days) later.

Exposure & Response Questions:

Healthcare Settings How do you protect patients at a doctor's office?

Basic infection control measures apply. They include:

• Plan to separate coughing or ill patients in the waiting area or have a separate area designated. Have a procedure or surgical masks for coughing patients readily available. Have disposable tissues readily available. Wear appropriate personal protective equipment (PPE) while performing exams, i.e. surgical masks with a coughing patient (to prevent droplet spread). This is the ideal time to determine immune status of personnel, either documentation of two MMRs, a positive mumps IgG or history of physician diagnosed mumps, or birth before 1957. If vaccination status is not adequate, vaccinate with MMR unless contraindicated. Don't forget it is also important to know the immune status of measles and other vaccine preventable diseases. Screen individuals for mumps symptoms when calling-in for an appointment. If clinically compatible with mumps, do not allow them to sit in the waiting area for prolonged periods of time and keep them at least three feet from other patients. Request that they wear a procedure or surgical mask. When assessing a patient for possible mumps, staff should follow Standard and Droplet Precautions. Any staff member with signs and symptoms of mumps should be sent home and be off work for nine days.
• See Guidelines for Infection Control in Healthcare Settings for more information.

Should actions be taken after a mumps case visits a doctor's office?

If an office assessment has not already been done, determine immunity of the office and medical personnel. This includes documentation of two doses of MMR, a positive mumps IgG, a history of physician diagnosed mumps, or birth before 1957. Administer MMR as needed. Susceptible personnel who have been exposed should be kept from direct patient contact from the 12th day after the first exposure through the 25th day after the last exposure. See Infection Control in Healthcare Settings for more information.

How do we prioritize MMR for HCW's?

Each facility needs to identify which staff has the greatest risk of contact with mumps cases and where further spread to susceptibles may occur. Areas to consider could include outpatient clinics, emergency departments, obstetrics, and areas with immunocompromised patients.

Do HCWs and patients need to wear N-95 masks?

No. Properly worn procedure or surgical masks are sufficient. HCWs should maintain Standard and Droplet Precautions when caring for and examining patients with respiratory symptoms. See Prevention & Control of Mumps Among Healthcare Personnel for more information.

School Settings What are the strategies for controlling mumps outbreaks in schools?

For all exposures consider the entire group that could have been exposed. That could be the whole school, whole work setting, etc. It is an opportunity to vaccinate susceptibles rather than individual persons. In the school setting all children K-12 should have documented evidence of receipt of two doses of MMR vaccine with few students on medical or religious exemptions. Do not forget to consider the staff as well.

What is the guidance for staff in a school?

Children K-12 should have documented evidence of receipt of two doses of MMR vaccine . Teachers and all staff should have their immune status verified (vaccination, serologic evidence of immunity, a history of physician diagnosed mumps, or birth before 1957). All staff should be educated on hygiene, prevention and signs and symptoms of disease.

Should we quarantine exposed people?

No. Current recommendations are to isolate individuals with symptoms by asking them to stay home from work or school for nine days after onset of symptoms.

Current Outbreak Questions:

Are we experiencing an outbreak of mumps?

Yes. In the United States, since 2001, an average of 265 mumps cases (range: 231-293) have been reported each year. This year so far, more than 600 mumps cases have been reported in Iowa alone.

Do we know why so many cases have had MMR vaccine?

Yes, some of the reported cases are in individuals that have been vaccinated with two doses of MMR. The vaccine effectiveness for one dose of MMR is 70-80% and 80-90% for two doses. Since no vaccine is 100 percent efficacious (even though people are vaccinated, the vaccine doesn't ‘take' in every person), it is to be expected that there will be some cases of disease in individuals that have been vaccinated. However, the vaccine is likely to have protected hundreds or thousands of additional cases.

Is the strain of mumps virus in Iowa and the Midwest a rare strain?

No, it is the same strain seen in an outbreak in England, and that has also been identified in Canada, Croatia, and Nepal.

Acronyms:
MMR – measles, mumps and rubella (vaccine)
HCW – health care worker

References:

• MMWR article Vaccine Use and Strategies for Elimination of Measles, Rubella, and Congenital Rubella Syndrome & Control of Mumps: Recommendations of ACIP     (.pdf)   May 22, 1998 / 47(RR-8);1-57)
• Pink book chapter on mumps  (also available in screen-reader device version)
• VPD Surveillance manual chapter on mumps
• Red Book online chapter on mumps (exit site)

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