Mumps

A mumps infection is usually recognised by the swollen cheeks caused by inflamed parotid salivary glands.

Summary

• Mumps is a viral illness that occurs everywhere in the world.
• It is recognised by characteristic facial swelling.
• It is generally a mild illness in children.
• Meningoencephalitis is a relatively frequent complication of mumps.

Description

A mumps infection is usually recognised by the swollen cheeks caused by inflamed parotid salivary glands. Sometimes mumps infection only becomes apparent because of complications, without the telltale facial swelling.

Cause

Mumps is caused by the mumps virus. There is only one strain of the virus, and it circulates all around the world. It is a human virus and can only be spread from one person to another. People are infectious for about a week before and after they develop symptoms of mumps. The virus is shed in saliva from the infected salivary glands and in the urine. Infection usually occurs by contact with infected saliva, either directly (for example by kissing), or indirectly, by airborne droplets. Droplets of saliva generated by sneezing or speech can be inhaled by a nearby person.

Symptoms

Early symptoms of mumps may be a mild fever and a general feeling of being unwell. Swelling and pain in the salivary glands are specific symptoms that soon develop. These glands, the parotid glands, lie in the cheeks over the lower jaw on either side of the face. The inflammation of the parotid glands (parotitis) caused by mumps may be on one side only, but usually it is on both sides. Sometimes other salivary glands are also involved, such as the submandibular glands, which lie below the lower jaw. Mumps parotitis causes discomfort during talking or eating.

About one third of people infected with mumps have no symptoms at all.

Mumps can have a number of complications. The commonest of these is meningitis, which affects one in 10 people with mumps. The symptoms of inflammation of the brain covering or meninges called meningitis are headache, stiff neck, avoidance of bright light (due to the pain it causes to the eyes), nausea and vomiting. It is not unusual in up to 50% of cases of mumps to have mumps meningitis without any sign of facial swelling or parotitis. A recent study showed that mumps is the second commonest cause of viral meningitis in Cape Town. Unlike bacterial meningitis, viral meningitis rarely has any serious consequences.

However, a rarer but more serious consequence of mumps is encephalitis, which affects boys more often than girls. Where meningitis is an inflammation of the surface of the brain, encephalitis is an inflammation of the deeper tissue of the brain. Early symptoms of encephalitis are emotional disturbance, irritability and drowsiness, which may progress to coma. Death from mumps is extremely rare, but when it does occur, it usually is the result of encephalitis. Most people recover from mumps encephalitis, but one possible consequence is deafness, usually affecting one ear only.

A well-known complication of mumps is inflammation of the testes, or orchitis (or-kite-iss). Orchitis usually occurs in individuals who get mumps when they are past puberty, and one in four of them are affected. Symptoms of orchitis are testicular swelling and pain, usually involving one testis only. With healing the testis or testes may shrink somewhat, but sterility is rare.

It is less well-known that post-pubertal girls and women occasionally experience inflammation of the ovaries. This can cause pain and tenderness in the lower abdomen. Girls and women are more often aware of inflammation of breast tissue, which also causes pain and tenderness to the touch.

A complication of mumps that tends to occur in post-pubertal boys and men particularly is a temporary arthritis. This causes aching, and possibly redness and swelling, of one or more joints.

A fairly rare (four in 100 people) but potentially serious complication of mumps is inflammation of the pancreas. This causes quite severe abdominal pain penetrating to the back. Very occasionally mumps pancreatitis can result in diabetes.

Mumps in the first trimester of pregnancy (up to 12 weeks) results in miscarriage in a quarter of cases. However, babies born to women who have had mumps during pregnancy have no increased risk of physical or mental abnormality.

Prevalence

Mumps virus most often infects children between five and nine years old. However, a fair number of people reach adulthood without having had the infection. Mumps infections tend to peak in winter or spring every two to five years. In countries where mumps vaccination is practised mumps has become quite rare, but this is not the case in South Africa since the measles, mumps, rubella vaccine (MMR) is only available through the private sector.

Risk factors

Anyone who has not been naturally infected or vaccinated is at risk of mumps in their lifetime. Fairly close contact with someone in the week before or after they develop the symptoms of mumps puts you at risk. This should be borne in mind when deciding when to allow children with mumps to return to school. As mentioned above, older teenagers and adults are at increased risk for certain of the complications of mumps. A second infection with mumps is rare.

When to see a doctor

Although mumps is a fairly easily recognisable illness, especially when there are several children involved, you may want confirmation from your health professional. A person who has symptoms of meningitis should always be seen by a doctor, and signs of encephalitis are a medical emergency. Any of the other complications of mumps will probably require a visit to a health professional for advice or treatment.

Diagnosis

A laboratory diagnosis is not usually necessary for mumps, because the appearance of a person with mumps is easily recognisable. However, quite often a person can have a complication, especially meningitis, without the typical facial swelling to indicate that mumps is responsible. In these instances the cause of the meningitis is usually investigated by doing a lumbar puncture and running several tests on the spinal fluid obtained in this way. (It is important to check that the meningitis is not the more serious bacterial type.) The mumps virus can be cultured from the spinal fluid. However, if mumps is suspected because of symptoms such as facial swelling, most laboratories will rather do a blood test to prove mumps infection.

Treatment

Home

• For an uncomplicated mumps infection you only need to keep the person as comfortable as possible.
• Soft or liquidised foods will help, and ice cream is likely to be appreciated!
• As with all viral infections, bed rest is advisable while there is a fever.
• In general, do not use aspirin-based drugs for children with a viral infection; paracetamol and mefenamic acid are suitable painkillers.

Medication

There is no drug that works against the mumps virus. All treatments for complications of mumps act to reduce particular symptoms, but do not affect the virus itself. Get advice from a health professional about treatment of common complications such as orchitis or arthritis; an anti-inflammatory drug is likely to be prescribed.

Prevention

The only way to avoid mumps or its complications is by vaccination. The mumps vaccine is usually available as part of the combined measles/mumps/rubella (MMR) vaccine. The recommended age for this vaccination is 15 months.

This combined vaccine is not provided by the state health services in South Africa, as there are currently more serious vaccination priorities (measles vaccine is given singly). The vaccine is however widely used in the private health sector.

The MMR vaccine is safe for most people. There are only a few reasons to avoid the vaccine:

• Severe immune impairment (the vaccine can be given to children with HIV before they develop Aids)
• Pregnancy (because of the theoretical risk that the vaccine virus can infect the foetus)
• Very severe egg allergy (as the vaccine virus is cultured in hen's eggs)
• Allergy to the antibiotic neomycin (neomycin is used as a preservative in the vaccine)

A rare risk of using the mumps vaccine is meningitis (approximately one person in 100 000 receiving the vaccine). This risk is much lower than in the case of natural mumps infection, where the figure for meningitis is one in 10 people. The meningitis caused by the vaccine is also mild, without long-term consequences.

(Reviewed by Dr Eftyhia Vardas, University of the Witwatersrand)