Mumps

The incidence of mumps in New Zealand has been stable in recent years. Mumps epidemics in New Zealand occurred in 1989 and 1994 while the most recent began in 2016 (mainly in Auckland region). Before the introduction of the measles–mumps–rubella (MMR) vaccine in 1990, mumps epidemics occurred every 3–5 years.

Detailed epidemiological information is available on the Institute of Environmental Science and Research (ESR) surveillance website in the annual notifiable disease reports.

Globally, mumps outbreaks continue to occur, especially in teenagers and young adults. These outbreaks are facilitated by mumps vaccine effectiveness (lower than for measles and rubella), waning vaccine-induced immunity and populations in settings more conducive to outbreaks (eg, schools, universities).

Given that mumps cases may only be mildly symptomatic, and that about a third of infections may be asymptomatic, infected (and possibly contagious) individuals may not consult health services. Therefore, identifying chains of transmission in an outbreak situation may be difficult.

An acute illness with unilateral or bilateral tenderness and swelling of the parotid or other salivary gland/s, lasting more than 2 days, with or without fever and without other apparent cause. Other clinical manifestations of mumps infection may uncommonly include orchitis, mastitis, oophoritis, meningitis, encephalitis, pancreatitis and hearing loss.

Laboratory definitive evidence for a confirmed case requires at least one of the following:

• detection of mumps virus nucleic acid (PCR) (recommended)
• isolation of mumps virus by culture.

If the case received a vaccine containing the mumps virus in the 6 weeks prior to symptom onset then laboratory definitive evidence requires also:

• evidence of infection with a wild-type virus strain obtained through genetic characterisation.

• Under investigation: A case that has been notified, but information is not yet available to classify it as probable or confirmed.
• Probable: A clinically compatible illness.
• Confirmed: A clinically compatible illness that is laboratory confirmed or epidemiologically linked to a confirmed case.
• Not a case: A case that has been investigated and subsequently found not to meet the case definition.

About 16–18 days, ranging from 12–25 days.

By droplet spread or by direct contact with saliva or fomites from an infected person.

People with mumps are most infectious from 2 days before to 5 days after the onset of parotitis. For contact tracing purposes the recommended period of communicability is also from 2 days before and 5 days after the onset of parotitis. However, mumps virus has been isolated in saliva from 7 days before to 9 days after the onset of parotitis. Asymptomatic cases also can be infectious.

Attending health practitioners or laboratories must immediately notify the local medical officer of health of suspected cases. Notification should not await confirmation.

Ascertain whether there is a history of vaccination and travel and identify any possible contacts, including travellers from overseas.

If no epidemiological link to a confirmed case is established, ensure laboratory confirmation by viral nucleic acid detection from a buccal swab taken ideally within 3 days, up to 7 days of parotitis onset. The buccal area to swab is the space near the upper rear molars between the cheek and gum (if unilateral parotitis, swab the affected side).

In a health care facility, implement droplet (in addition to standard) precautions for 5 days after the onset of glandular swelling.

Exclude cases from school, university, sports, early childhood services, health care employment or other work, and from close contact with other susceptible people for 5 days from onset of glandular swelling.

Advise the case and their caregivers of the nature of the infection and its mode of transmission. In particular, advise good hand hygiene, cough/sneeze etiquette, avoiding sharing food/drink/utensils, and social distancing.

Any person with close contact[1] (eg, through household, early childhood services, school, workplace, camp, cultural or sports-related activities, transportation or social mixing) with the case during the period of communicability.

Susceptible contact

Anyone born after 1981 who has not had mumps infection or has not been fully vaccinated for their age.[2]

In an outbreak, obtain a history of previous immunisation or natural illness with mumps to identify susceptible contacts.

Serological screening to identify susceptible contacts is not recommended. The presence of mumps-specific IgG does not necessarily predict protection from mumps disease despite it being considered as evidence of mumps immunity.

Advise exclusion of susceptible contacts in health care settings and for those working or living with immune-compromised people from 12 days after the first exposure to 25 days after last exposure to the infectious case. Documented full immunisation with two MMR doses should be required in these situations.

In general, consider advising exclusion of susceptible contacts with zero MMR doses from tertiary education, school or early childhood services or work from 12 days after the first exposure to 25 days after last exposure to the infectious case, if there is a high risk of mumps transmission.

Exclusion is more important in secondary and tertiary education settings as these settings are more conducive to outbreaks.

All excluded contacts in settings other than health care or with immunocompromised people can be readmitted immediately after they have received the first MMR dose. Those who have a history of one dose of MMR vaccination should be offered their second vaccine dose and be allowed to remain in tertiary education, school, early childhood services or work (except for those in health care settings and for those working or living with immunocompromised people). However, if the contact subsequently develops mumps symptoms they would need to be excluded.

These measures will increase overall immunity in these populations and limit the spread of mumps (as well as protecting against measles and rubella), but also minimise the disruption due to exclusion.

All vaccinations given should be recorded on the National Immunisation Register via the Practice Management Systems or by completing the NIR3 immunisation event form and sending this to the District Health Board NIR Administrator. 

Passive immunisation is not effective. Active immunisation with MMR vaccine is not considered effective against incubating infection, but MMR should be offered to susceptible contacts for protection against future exposure.

Advise good hand hygiene, cough/sneeze etiquette, avoiding sharing food/drink/utensils, and social distancing. Advise all contacts of the incubation period and typical symptoms of mumps. Encourage them to seek early medical attention and avoid contact with others if symptoms develop.

Make sure that all those born after 1969 and who are susceptible are offered MMR vaccine, with priority given to those born after 1981.

Check for other cases in the community.

Clean and disinfect surfaces and articles soiled with saliva or urine. For more details, refer to Appendix 1: Disinfection.

Encourage complete childhood vaccination with the MMR vaccine. This currently involves two doses, the first at 12 months of age and the second at 15 months of age.

Encourage early childhood services to keep up-to-date immunisation records.

The focus of the Public Health response should be:

• to increase population immunity against measles, mumps and rubella
• to limit outbreaks in settings where transmissions may be more intense and prompt public health intervention may be effective (especially secondary and tertiary education)
• to stop any spread in health care settings, and protect immune-compromised people.

Immunisation response should be prioritised.

Ensure complete case information is entered into EpiSurv.

If a cluster of cases occurs, contact 0800GETMOH - CD option, and outbreak liaison staff at ESR, and complete the Outbreak Report Form.

• CDC. 2019. Mumps (accessed 20 November 2020).
• CDC. 2018. Chapter 9: Mumps. Manual for the Surveillance of Vaccine-Preventable Diseases. Atlanta: Centers for Disease Control and Prevention. 
• Communicable Disease Network Australia. 2004. Mumps case definition. Australian national notifiable diseases case definitions (accessed 20 November 2020).
• Dayan GH, Rubin S. 2008. Mumps Outbreaks in Vaccinated Populations: Are Available Mumps Vaccines Effective Enough to Prevent Outbreaks? Clinical Infectious Diseases 1;47(11):1458-67.
• Heymann D (ed). 2014. Control of Communicable Diseases Manual (20th edition). American Public Health Association.
• Kutty PK, Kyaw MH, Dayan GH, Brady MT, Bocchini JA, Reef SE, Bellini WJ, Seward JF. 2010. Guidance for isolation precautions for mumps in the United States: a review of the scientific basis for policy change. Clinical Infectious Diseases 50(12):1619-28.
• Ministry of Health. 2020. Immunisation Handbook 2020. Wellington: Ministry of Health.
• Public Health England. 2013. Mumps: epidemiology, surveillance and control (accessed 20 November 2020).
• Rubin SA, Link MA, Sauder CJ, Zhang C, Ngo L, Rima BK, Duprex WP. 2012. Recent mumps outbreaks in vaccinated populations: no evidence of immune escape. Journal of Virology 86(1):615-20. doi: 10.1128/JVI.06125-11.

[1]   For practical reasons close contact may be defined as face-to-face contact within 1 metre.

[2]    Mumps vaccine was first offered in the 1990 schedule as MMR at 15 months and a second dose was introduced in 1992 at 11 years. However, any person born from 1 January 1969 who does not have two documented doses of MMR vaccine given at least four weeks apart with the first dose given any time after the age of 12 months should be offered the vaccine to protect them against measles,  rubella and mumps.