Mumps is the result of infection with a paramyxovirus. It is spread by droplet infection, by direct contact or through fomites. Humans are the only known natural hosts. The peak period of infectivity is 2-3 days before the onset of the parotitis and for 3 days afterwards.

Clinical features

The incubation period averages 18 days. Although no age is exempt, it is primarily a disease of school-aged children and young adults; it is uncommon before the age of 2 years. The prodromal symptoms are non-specific and include fever, malaise, headache and anorexia. This is usually followed by severe pain over the parotid glands, with either unilateral or bilateral parotid swelling. The enlarged parotid glands obscure the angle of the mandible and may elevate the ear lobe, which does not occur in cervical lymph node enlargement. Trismus due to pain is common at this stage. Submandibular gland involvement occurs less frequently.

Complications

CNS involvement is the most common extrasalivary-gland manifestation of mumps. Clinical meningitis occurs in 5% of all infected patients, and 30% of patients with CNS involvement have no evidence of parotid gland involvement.

Epididymo-orchitis develops in about one-third of patients who develop mumps after puberty. Bilateral testicular involvement results in sterility in only a small percentage of these patients. Pancreatitis, oophoritis, myocarditis, mastitis, hepatitis and polyarthritis may also occur.

Diagnosis and treatment

The diagnosis of mumps is on the basis of the clinical features. In doubtful cases, serological demonstration of a fourfold rise in antibodies detected by complement fixation or indirect haemagglutination or neutralization tests on acute and convalescent sera is diagnostic. Virus can be isolated in cell culture from saliva, throat swab, urine and CSF and identified by immunofluorescence or haemadsorption.

Treatment is supportive. Attention should be given to adequate nutrition and mouth care. Analgesics should be used to relieve pain.

Prevention

Active immunization.

Children are immunized with the MMR vaccine. Vaccination is contraindicated in immunosuppressed individuals, during pregnancy, or in those with severe febrile illnesses.