Mumps is a viral infection of the salivary glands, especially the parotid glands that run along the angle of the jaw in front of and below each ear.
Children between the ages of 5 and 10 are most likely to contract mumps. Being infected once gives you lifelong immunity.
Mumps is most common around the month of March. It usually appears in scattered individual cases, though there are occasional local epidemics among unvaccinated children.
It’s less infectious than chickenpox or measles. Unvaccinated adults who never had the disease are at much higher risk of complications than are children, but mumps rarely causes serious problems.
A vaccine for mumps dramatically reduced the incidence of the disease since its introduction in 1967. In the 1950s, Canada had about 30,000 cases a year.
The advent of the vaccine cut that number in half. Today, the annual incidence is under 300 cases per year.
Causes of Mumps
Mumps is caused by an organism called a paramyxovirus. It’s transmitted via the mouth by tiny drops of saliva from talking, sneezing, sharing drinks, kissing, or coughing.
The virus can land on an object that others then handle. Once it’s on your hand, there’s a good chance it will find its way into your mouth, especially if you’re a young child.
Mumps is contagious for about a week before the glands swell, and about 9 days afterwards, so people can transmit it before they know they have it. This is common for most viral diseases.
Mumps is an acute, generalised infection caused by a paramyxovirus, usually in children and young adults.
It can infect any organ but usually affects the salivary glands and, less often, the pancreas, testis, ovary, brain, mammary gland, liver, kidney, joints and heart.
The incubation period is between around 17 days (14-25 days).
The virus is highly infectious with transmission by droplets spread in saliva via close personal contact.
Infected persons excrete the virus for several days before symptoms appear and for several days afterwards.
Since the introduction of the measles, mumps and rubella (MMR) vaccine, mumps has become a notifiable disease to help monitor the effectiveness of the vaccine.
Either clinical or subclinical infection used to be very common in childhood but, with the introduction of the MMR vaccine in 1987, numbers dwindled considerably.
Since 2004, the majority of the confirmed cases have been linked with outbreaks in universities. Many confirmed cases were still unvaccinated or had only received one dose of the MMR vaccine.
There were around 2465 cases in total in 2011 in England and Wales but this remains well below figures seen in the last mumps epidemic in 2005 when there were 43,378.
Mumps can be asymptomatic.
Nonspecific symptoms lasting a few days, such as fever, headache, malaise, myalgia and anorexia, can precede parotitis.
Parotitis is usually bilateral although it can be unilateral.
Typically, there is pain at or near the angle of the jaw.
Fever may be as high as 39.5°C without rigors in small children.
Swelling causes distortion of the face and neck with skin over the gland hot and flushed but there is no rash.
With severe swelling, the mouth cannot be opened and is dry because the salivary ducts are blocked.
Discomfort lasts for three or four days but may be prolonged when one side clears and the other side swells.
Usually just the parotid glands are involved but, rarely, the submaxillary and sublingual salivary glands are affected.
Symptoms and Complications of Mumps
Up to one-third of people infected feel no symptoms. Others have a low-grade fever, headache, weakness, fatigue, and loss of appetite starting 14 to 24 days after they are actually infected.
About a day after the onset of fever, the parotid gland near the ear begins to swell and ache – this makes chewing and swallowing painful. The body’s temperature rises to 39.5°C to 40°C (103°F to 104°F).
The swelling and tenderness worsens over the next 3 days and may extend forward of the jaw and, for some, down the neck, depending on whether other salivary glands are involved.
In the majority of mumps cases, both the right and left parotid glands are swollen. The fever typically lasts only 1 to 3 days but can persist for a week. The swelling of the glands tends to resolve after about one week.
That’s usually as far as it goes, even in adults. 1 in 5 adolescent or adult males, however, suffers orchitis, an infection and inflammation of the testicles.
This can be very painful, but it almost never results in sterility. Women can get an infection in the ovaries, but it’s mild and harmless.
1 in 30 people infected get pancreatitis (inflammation of the pancreas) with vomiting and stomachache that quickly clears up. A similar number develop hearing problems due to otitis media, which is also a temporary side effect of mumps.
Any viral disease carries some risk of severe complications like encephalitis (brain inflammation) or meningitis (inflammation of the membranes around the brain and spinal cord) during or after the initial infection.
The risk of developing encephalitis with mumps is about 1 in 5,000, and for meningitis the risk is 1% to 10%. There is a very small risk of miscarriage in women who get infected while pregnant.
Orchitis may occur four or five days after the start of parotitis but it often appears without it. This can sometimes lead to the diagnosis being missed.
Orchitis presents with chills, sweats, headache and backache with swinging temperature and severe local testicular pain and tenderness.
- The scrotum is swollen and oedematous so that the testes are impalpable.
- Orchitis is usually unilateral but may be bilateral.
- Sometimes, as one side resolves, orchitis strikes the other side three or four days later.
- Orchitis occurs in around 25% of postpubertal men.
- Subfertility following bilateral orchitis is rare.
- Meningitis and encephalitis
- Mumps frequently affects the nervous system.
- Meningism occurs in around 15% of patients.
- It usually occurs without parotitis.
- Meningitis is usually mild and self-limiting.
- Mumps encephalitis may present early by direct invasion following initial infection, or late as a post-infectious event.
Although rarely fatal, other complications of mumps can include:
- Oophoritis, which may cause pain in 5% of postpubertal females; sterility seldom occurs.
- Profound deafness (in one ear in 1 in 15,000 of cases, which is usually transient).
- Pancreatitis occurs in around 4% of cases.
- Mild upper abdominal pain (may be related to the pancreas in around 50% of cases).
- Neuritis, arthritis, nephritis, thyroiditis and pericarditis have all been reported.
- Transient and mild mastitis (uncommon – can occur in either sex).
- Mumps in the first trimester of pregnancy may increase the rate of spontaneous abortion but the virus is not teratogenic.
By far the most common presentation of mumps is with parotitis. High temperature, pain and swelling in the neck are common with many other infections, including tonsillitis, viral pharyngitis and infectious mononucleosis.
The tender, swollen parotid glands emerge from behind the ramus of the mandible and can be distinguished from lymph nodes in that on palpation it is not possible to feel in front of the parotid glands.
HIV infection should be considered.
Patients with a stone in the parotid duct tend to be older but a much more important feature is that the gland swells and becomes more painful on chewing as saliva is produced.
Mumps must be in the differential diagnosis of viral meningitis and encephalitis.
Mumps orchitis typically strikes the same age as torsion of the testis. In torsion, the testis is usually still palpable with the long axis horizontal. There is no pyrexia and there are no other aches and pains.
In most cases, the diagnosis can be made clinically without need for investigations.
In patients with meningitis but without parotitis, the diagnosis may be confirmed by detection of mumps-specific antibodies in the serum.
Salivary immunoglobulin M (IgM) against mumps may be detected. Confirmation of clinical diagnosis by oral fluid testing is offered by the Health Protection Agency (HPA).
Specific antibody levels may not rise for several days and so, if the result is negative but clinical suspicion is strong, it is worth repeating the test.
A rapid real-time test using mumps RNA present in serum has been developed. This is particularly useful if salivary IgM is negative but clinical suspicion is high.
High-resolution and colour Doppler ultrasound has been used to differentiate mumps orchitis from torsion.
Keep up fluids and keep the mouth moist.
There is no specific treatment but drugs such as paracetamol and ibuprofen may give symptomatic relief.
For mumps orchitis, treatment is initially conservative with bed rest, fluids and analgesia.
Treating and Preventing Mumps
Mumps is caused by a virus, and we can’t cure viral diseases. Fortunately our immune system can deal with mumps, so the treatment for mumps is to wait for it to go away.
Eating soft foods and avoiding acidic foods such as orange juice can help cope with the symptoms.
You can fight fever, headache, and muscle pains with acetaminophen* or ibuprofen. Never give acetylsalicylic acid (ASA) to children with a viral infection, as its use in these circumstances is linked to a dangerous condition called Reye’s syndrome.
Orchitis (swelling of the testicles) requires bed rest for a day or two. Letting the testicles hang increases swelling, so they should be propped up. A tape bridge between the thighs may help, as may an ice pack wrapped in a towel.
You can easily prevent mumps with the highly safe and effective measles, mumps, and rubella (MMR) vaccine. It is usually given to children after 1 year of age, just when they’re starting to lose the natural immunity that is transmitted from their mother prior to birth.
Many programs give boosters a few months or years later, usually before a child begins school.
It’s recommended that unvaccinated young adults get immunized. Older adults are almost certain to be immune. If you lived as a child with a sibling who had mumps, you can assume you’re immune.
You can also help prevent mumps by avoiding contact with people who have mumps, washing your hands regularly, and not sharing drinks.
Women who are thinking of getting pregnant and have never had the disease or an MMR shot should be vaccinated before getting pregnant. Talk to a doctor about your options.
Most cases see full recovery. The mortality rate from central nervous system involvement is about 1%. Deaths from other causes are rare, more than half the cases arising in men over the age of 19 years.
MMR vaccine is given in the national immunisation programme.
Normal hygiene measures to prevent droplet infection should be instituted in the household of a patient who has mumps.
Children should be excluded from school for five days following onset of parotid swelling.