Mumps

   

Mumps
Classification and external resources
Child with mumps

Mumps (epidemic parotitis) is a viral disease of the human species, caused by the mumps virus. Before the development ofvaccination and the introduction of a vaccine, it was a common childhood disease worldwide. It is still a significant threat to health indeveloping countries, and outbreaks still occur sporadically in developed countries.^[1]

Painful swelling of the salivary glands – classically the parotid gland – is the most typical presentation.^[2] Painful testicular swelling (orchitis) and rash may also occur. The symptoms are generally not severe in children. In teenage males and men, complications such as infertility or subfertility are more common, although still rare in absolute terms.^[3][4][5] The disease is generally self-limiting, running its course before receding, with no specific treatment apart from controlling the symptoms with pain medication.

Fever and headache are prodromal symptoms of mumps, together with malaise and anorexia. Other symptoms of mumps can include dry mouth, sore face and/or ears and occasionally in more serious cases, loss of voice. In addition, up to 20% of persons infected with the mumps virus do not show symptoms, so it is possible to be infected and spread the virus without knowing it.^[6]

Males past puberty who develop mumps have a 15–20 percent risk of orchitis,^[7] painful inflammation of the testicles.^[8]

Cause

Mumps is a contagious disease that is spread from person to person through contact with respiratory secretions, such as saliva from an infected person. When an infected person coughs or sneezes, the droplets aerosolize and can enter the eyes, nose, or mouth of another person. Mumps can also be spread by sharing food and drinks. The virus can also survive on surfaces and then be spread after contact in a similar manner.

A person infected with mumps is contagious from approximately 6 days before the onset of symptoms until about 9 days after symptoms start.^[9][10] The incubation period (time until symptoms begin) can be from 14–25 days, but is typically 16–18 days.^[11]

Diagnosis

A physical examination confirms the presence of the swollen glands. Usually, the disease is diagnosed on clinical grounds, and no confirmatory laboratory testing is needed. If there is uncertainty about the diagnosis, a test of saliva or blood may be carried out; a newer diagnostic confirmation, using real-time nested polymerase chain reaction (PCR) technology, has also been developed.^[12] An estimated 20%-30% of cases are asymptomatic.^[13] As with any inflammation of the salivary glands, serum amylase is often elevated.^[14][15]

Prevention

The most common preventative measure against mumps is a vaccination with a mumps vaccine, invented by American microbiologist Maurice Hilleman at Merck.^[16] The vaccine may be given separately or as part of the MMR immunization vaccine which also protects against measles and rubella. In the US, MMR is now being supplanted by MMRV, which adds protection against chickenpox. The WHO (World Health Organization) recommends the use of mumps vaccines in all countries with well-functioning childhood vaccination programmes. In the United Kingdom it is routinely given to children at age 13 months with a booster at 3–5 years(preschool) This confers lifelong immunity. The American Academy of Pediatrics recommends the routine administration of MMR vaccine at ages 12–15 months and at 4–6 years.^[17] In some locations, the vaccine is given again between 4 to 6 years of age, or between 11 and 12 years of age if not previously given. The efficacy of the vaccine depends on the strain of the vaccine, but is usually around 80%.^[18][19]The Jeryl Lynn strain is most commonly used in developed countries but has been shown to have reduced efficacy in epidemic situations. The Leningrad-Zagreb strain commonly used in developing countries appears to have superior efficacy in epidemic situations.^[20]

Because of the outbreaks within college and university settings, many governments have established vaccination programs to prevent large-scale outbreaks. In Canada, provincial governments and the Public Health Agency of Canada have all participated in awareness campaigns to encourage students ranging from grade 1 to college and university to get vaccinated.^[21]

Some anti-vaccine activists protest against the administration of a vaccine against mumps, claiming that the attenuated vaccine strain is harmful, and/or that the wild disease is beneficial. There is no evidence whatsoever to support the claim that the wild disease is beneficial, or that the MMR vaccine is harmful. Claims have been made that the MMR vaccine is linked to autism and inflammatory bowel disease, including one study by Andrew Wakefield^[22][23] (the paper was discredited and retracted in 2010 and Wakefield was later stripped of his license after his work was found to be an "elaborate fraud" ^[24]) that indicated a link between gastrointestinal disease, autism, and the MMR vaccine. Also, subsequent studies indicate no link between vaccination with the MMR and autism.^[25] Since the dangers of the disease are well known, while the dangers of the vaccine are quite minimal, most doctors recommend vaccination.

The WHO, the American Academy of Pediatrics, the Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention, the American Academy of Family Physicians, the British Medical Association and the Royal Pharmaceutical Society of Great Britain currently recommend routine vaccination of children against mumps. The British Medical Association and Royal Pharmaceutical Society of Great Britain had previously recommended against general mumps vaccination, changing that recommendation in 1987. In 1988 it became United Kingdom government policy to introduce mass child mumps vaccination programmes with the MMR vaccine, and MMR vaccine is now routinely administered in the UK.^{[citation needed]}

Before the introduction of the mumps vaccine, the mumps virus was the leading cause of viral meningoencephalitis in the United States. However, encephalitis occurs rarely (less than 2 per 100,000).^[26] In one of the largest studies in the literature, the most common symptoms of mumps meningoencephalitis were found to be fever (97%), vomiting (94%) and headache (88.8%).^[27] The mumps vaccine was introduced into the United States in December 1967: since its introduction there has been a steady decrease in the incidence of mumps and mumps virus infection. There were 151,209 cases of mumps reported in 1968. Since 2001, the case average was only 265 per year, excluding an outbreak of >6000 cases in 2006 attributed largely to university contagion in young adults.^[28][29]

Treatment

There is no specific treatment for mumps. Symptoms may be relieved by the application of intermittent ice or heat to the affected neck/testicular area and byacetaminophen/paracetamol for pain relief. Warm saltwater gargles, soft foods, and extra fluids may also help relieve symptoms. Acetylsalicylic acid (aspirin) is not used due to the risk of Reye's syndrome.

According to the Department of Health of Minnesota there is no effective post-exposure recommendation to prevent secondary transmission, nor is the post-exposure use of vaccine or immunoglobulin effective.^[30]

Patients are advised to avoid acidic foods and beverages, since these stimulate the salivary glands, which can be painful.^[31]

Prognosis

Death is very unusual. The disease is self-limiting, and general outcome is good, even if other organs are involved. Known complications of mumps include:

• Infection of other organ systems
• Mumps viral infections in adolescent and adult males carry an up to 30% risk that the testes may become infected (orchitis or epididymitis), which can be quite painful; about half of these infections result in testicular atrophy, and in rare cases sterility can follow.^[32]
• Spontaneous abortion in about 27% of cases during the first trimester of pregnancy.^[32]
• Mild forms of meningitis in up to 10% of cases^[32] (40% of cases occur without parotid swelling)
• Oophoritis (inflammation of ovaries) in about 5% of adolescent and adult females,^[32] but fertility is affected in almost half of these 5%.
• Pancreatitis in about 4% of cases, manifesting as abdominal pain and vomiting
• Encephalitis (very rare, and fatal in about 1% of the cases when it occurs)^[32]
• Profound (91 dB or more) but rare sensorineural hearing loss, uni- or bilateral. Acute unilateral deafness occurs in about 0.005% of cases.^[32]

After the illness, lifelong immunity to mumps generally occurs; reinfection is possible but tends to be mild and atypical.