Overview
Mumps is a viral illness, which can cause swelling and tenderness of one or more salivary (parotid) glands. Some people with mumps have no symptoms and others may only have symptoms in other organs, for example, meningitis or inflammation of the testicles (orchitis). New Zealand had a mumps epidemic in 1994, and a large outbreak that lasted three years over 2017–2019.
Mumps incidence in New Zealand has been stable in recent years. Internationally, mumps outbreaks continue to occur, particularly in settings where people have frequent, close contact. Although mumps can occur in vaccinated people, vaccination reduces the risk of infection and complications.
Introduction
Mumps is a contagious viral infection caused by the mumps virus. It most commonly affects the salivary glands, particularly the parotid glands located below and in front of the ears. Infection can cause no symptoms or a range of symptoms and complications.
Transmission
Mumps is spread through the air from person to person by coughing and sneezing, and by direct contact with infected saliva.
The incubation period (time from infection to onset of symptoms) is on average 16-18 days, and ranges from 12-25 days. A person with mumps is most infectious from two days before to five days after the onset of parotitis (salivary gland swelling). People without symptoms are also contagious.
Symptoms
At least 30% of mumps infections in children are asymptomatic. Complications are generally more common in adolescents and adults than in children.
Most children under two years of age have no symptoms when they get mumps. Those who get mumps as an adult are more likely to experience severe disease.
When symptoms are present they usually include; fever, headache, malaise, muscle aches, poor appetite, swelling and tenderness of one or more salivary glands (just below the ear lobe). However, some people have symptoms in organs other than the salivary glands. For example mumps meningitis may present as headache, sensitivity to light, neck stiffness, fever and/or vomiting.
On average, fever usually lasts one to six days. Parotid swelling generally peaks within one to three days and then starts to improve during the following week.
Treatment
There is no treatment for the mumps infection. Management of symptoms is focused on improving comfort.
Supportive care includes rest, plenty of fluids, pain and fever relief, and applying cold compresses to swollen glands.
Risks
Mumps can occur in vaccinated people, particularly in close-contact settings, but vaccinated people are significantly less likely to experience complications. Complications are generally more common in adolescents and adults than in children.
- Unvaccinated adolescents and adults are most at risk, and are more likely to experience severe mumps disease and complications
- Viral (mumps) meningitis occurs in 5-10% of symptomatic mumps cases, long term consequences are very rare
- Temporary deafness to high frequency sounds occurs in 4 in 100 cases. Profound and permanent deafness is rare, usually on one side, and occurs in 1 in 15,000 cases
- Orchitis (inflamed testicle), usually one-sided, occurs in around 30% of unvaccinated and 6% of vaccinated post-pubertal males. Among unvaccinated post-pubertal females, oophoritis (inflamed ovary) occurs in around 7% and mastitis (inflammation of the breast) in up to 30%; both occur in 1% or less of vaccinated cases. Sterility occurs rarely.
- Encephalitis (brain inflammation) occurs in around 1 in 6,000 cases
- Death from mumps is exceedingly rare. The overall case fatality rate from mumps is about 1.8 per 10,000 cases
- Inflammation of other organs, such as pancreas, nerves, joints, breast, kidney, thyroid and heart, is possible
- Pregnant women who get mumps during the first trimester of pregnancy may have an increased risk of miscarriage, but there is no evidence that mumps causes fetal abnormalities
Prevention
Immunisation given on-time is the best method of preventing mumps. The measles, mumps, rubella vaccine (MMR) is given as part of the National Immunisation Schedule at 12 months and 15 months of age. No mumps-only vaccine is available in New Zealand.
People with mumps are excluded from early childhood education, school and work for five days after the appearance of swollen salivary gland swelling to protect others from infection.
Contacts should follow advice from the National Public Health Service. Susceptible contacts may need to stay away from early childhood education, school, tertiary education, or work from 12 days after their first exposure until 25 days after their last exposure, depending on their vaccination status, setting, and risk of transmission.
MMR vaccine given after exposure is not considered effective against an infection that is already incubating, but susceptible contacts should be offered vaccination to protect against future exposure.
For further information, see the IMAC resources, including information on vaccination, vaccine safety, effectiveness and the New Zealand Immunisation Schedule.
