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 (either unilateral or bilateral), though only 30%-40% of mumps infections produce typical acute parotitis. The parotitis develops an average of 16-18 days after exposure. Swelling may also be seen in the submandibular or sublingual glands in a small percentage of cases. Nonspecific symptoms including myalgia, anorexia, malaise, headache, and low-grade fever may precede parotitis by several days. Nonspecific or primarily respiratory symptoms are the only manifestations of infection in 40%-50% of mumps cases, and particularly cases in children less than 5 years of age. Fifteen to twenty percent of mumps virus infections 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 2 days before until 5 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 saliva 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 less than 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 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 generally resolves without sequelae. Mumps infection in the first trimester of pregnancy may result in fetal loss. There is no evidence that mumps during pregnancy causes congenital malformations.
What are the 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 the public health definition of mumps?
(reportable to OHS) Isolation of mumps virus from any clinical specimen, or Acute onset of tender, self-limited swelling of any salivary gland, lasting 2 or more days, and without other apparent cause plus one of the folowing:
• Detection of mumps virus nucleic acid from a clinical specimen, or
• Acute- and convalescent-phase mumps IgG assays by any standard serologic assay showing at least a 4-fold titer increase and not explained by vaccination or receipt of antibody-containing blood products, or
• Positive serologic test for mumps immunoglobulin M (IgM) antibody not explained by vaccination or receipt of antibody-containing blood products.
(reportable to OHS)
Any person epidemiologically linked to a confirmed case, with acute onset of tender, self-limited swelling of a salivary gland lasting >2 days, and lacking any other apparent cause. The salivary gland swelling can be unilateral or bilateral, and it doesn’t have to be the parotid.
(not reportable to OHS)
Any patient who would be presumptive if only they were epi-linked! Suspect cases should be reported by physicians to local health departments, but are not officially reportable to ACDP. (Of course, we’re always happy to talk about them and help arrange for the kind of testing that may upgrade their status.)
What should I do if I suspect that my patient has mumps?
- Notify the local health department of the suspected case. Be prepared to give the demographic and clinical information, along with the case’s contact information so that local public health workers can follow up on the case.
- Obtain specimens for lab testing. Remember that not all parotitis is mumps. Obtain specimens as soon as possible after symptom onset.
Currently OSPHL performs no test for mumps, but both IgM and IgG antibodies assays are available commercially. Acute serum samples should be collected within 5 days of onset; with convalescent 2–5 weeks after that.
As with measles and rubella, elevated mumps IgM levels may be transient or absent in persons who have had any doses of mumps-containing vaccine. Experience suggests that IgM assays from persons with acute infections may be negative in up to 50% of previously immunized individuals (i.e., a negative IgM does not rule out infection in a vaccinated person).
In contrast, IgG levels in previously vaccinated individuals may rise rapidly after exposure or infection. By the time an “acute” sample is collected, IgG levels may already be sky high, often making it difficult to detect a 4-fold rise in a convalescent specimen.
As the outbreak progresses, the recommendation to try to confirm each case with laboratory testing may be re-evaluated.
- Take an exposure history. Ask the case about contacts with other known cases or travel to areas where mumps is prevalent.
- Obtain documentation of immunization history. Verbal history of receipt of mumps vaccine is not considered adequate proof of vaccination.
How are mumps outbreaks controlled?
Mumps is the only known cause of epidemic parotitis. The main strategy for controlling a mumps outbreak is to define the at-risk population and setting of transmission, and rapidly to identify and vaccinate susceptible persons or, if a contraindication exists, to exclude susceptible persons from the setting to prevent exposure and transmission.
Mumps vaccine, preferably as MMR, should be administered to susceptible persons. Although mumps 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 infected. If susceptible persons can be vaccinated early in the course of an outbreak, they can be protected. However, cases are expected to continue to occur among newly vaccinated persons who are already infected for at least 3 weeks following vaccination because of the long incubation period for mumps.
As with all vaccines, the effectiveness of mumps vaccine is not 100%; therefore, a second dose of mumps-containing vaccine is recommended during outbreak situations for at-risk individuals who have received only one dose. Studies have shown a trend toward a lower attack rate among children who have received two doses of mumps vaccine as opposed to those who have received one dose. Furthermore, birth before 1957 does not guarantee mumps immunity, and in outbreak settings vaccination with a mumps-containing vaccine should be considered for those born before 1957 who may be exposed to mumps and who may be susceptible.
Exclusion of susceptible students from schools affected by a mumps outbreak (and other, unaffected schools judged by local public health authorities to be at risk for transmission of disease) should be considered to control mumps outbreaks. Once vaccinated, students can be readmitted to school. Students who have been exempted from mumps vaccine for medical, religious, or other reasons should be excluded through at least 25 days after the onset of parotitis in the last person with mumps in the affected school.
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 at or greater than 12 months of age receive 1 dose of MMR vaccine that all school-aged children receive 2 doses of MMR, and 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, HCWs may be at increased risk of acquiring mumps and transmitting it to patients, and therefore should receive 2 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 should review the vaccination status of populations of interest and work to address gaps in vaccination.
See also: CDC Measles, Mumps and Rubella— Vaccine Use and Strategies for Elimination of Measles, Rubella, and Congenital Rubella Syndrome & Control of Mumps: Recommendations of ACIP
MMWR 47(RR-8):1–57. Available at http://www.cdc.gov/mmwr/PDF/rr/rr4708.pdf
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, seroconversion may not result in immunity. About 70%-80% of persons who have received 1 dose and 80%-90% of those who have received 2 doses are protected.
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 CDC. Measles, Mumps and Rubella-Vaccine Use and Strategies for Elimination of Measles, Rubella, and Congenital Rubella Syndrome & Control of Mumps: Recommendations of ACIP MMWR 47(RR-8):1-57.
Can healthcare workers 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.
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, and the American Academy of Family Physicians. If the outbreak affects the 1-4 -year-old age group, then the children should receive their 2nd MMR dose now, provided that 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 K-12 have received 2 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 2 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 at least 28 days later.
How does one 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 while performing exams, e.g., surgical masks with a coughing patient (to prevent droplet spread). This is the ideal time to determine the immune status of personnel, either documentation of 2 doses of MMR, 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 that it is also important to know the immune status of measles and other vaccine preventable diseases. Screen individuals for mumps symptoms when they call in for an appointment. If they have symptoms suggesting mumps, do not allow them to sit in the waiting area for prolonged periods of time and keep them at least 3 feet from other patients. Ask 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 suspected mumps should be sent home and be off work for nine days.
Should actions be taken after a mumps case visits a doctor's office?
If an office assessment has not already been done, determine the immune status of the office and medical personnel as above, and 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.
How do we prioritize MMR for HCWs?
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.
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 in grades K-12 should have documented evidence of receipt of 2 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 in grades K-12 should have documented evidence of receipt of 2 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?
Not unless they lack evidence of immunity, in which case they should stay home from work or school from the 12th day after the first exposure through the 25th day after the last exposure.
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. In 2006, more than 2,000 mumps cases were 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 1 dose of MMR is 70-80% and 80-90% for 2 doses. Since no vaccine is 100% effective (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 prevented hundreds or thousands of other 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.
Source: National Immunization Program web site: http://www.cdc.gov/nip/diseases/mumps/mumps-tech-faqs.htm
Mumps in the Midwest - CD Summary May 2, 2006 (Vol. 55, No. 9 )