Measles (rubeola)

Measles is a highly communicable disease that occurs world-wide. With the introduction of aggressive immunization policies, the incidence of measles has fallen dramatically in the West, but it still remains one of the most common childhood infections in resource-deprived countries, where it is associated with a high morbidity and mortality. It is spread by droplet infection and the period of infectivity is from 4 days before until 2 days after the onset of the rash.

Clinical features

The incubation period is 8-14 days. Two distinct phases of the disease can be recognized.

Typical measles

The pre-eruptive and catarrhal stage. This is the stage of viraemia and viral dissemination. Malaise, fever, rhinorrhoea, cough, conjunctival suffusion and the pathognomonic Koplik's spots are present during this stage. Koplik's spots are small, greyish, irregular lesions surrounded by an erythematous base and are found in greatest numbers on the buccal mucous membrane opposite the second molar tooth. They occur a day or two before the onset of the rash.
The eruptive or exanthematous stage. This is characterized by the presence of a maculopapular rash that initially occurs on the face, chiefly the forehead, and then spreads rapidly to involve the rest of the body. At first the rash is discrete but later it may become confluent and patchy, especially on the face and neck. It fades in about 1 week and leaves behind a brownish discoloration.
Although measles is a relatively mild disease in the healthy child, it carries a high mortality in the malnourished and in those who have other diseases. Complications are common in such individuals and include bacterial pneumonia, bronchitis, otitis media and gastroenteritis. Less commonly, myocarditis, hepatitis and encephalomyelitis may occur. In those who are malnourished or those with defective cell-mediated immunity, the classical maculopapular rash may not develop and widespread desquamation may occur. The virus also causes the rare condition, subacute sclerosing panencephalitis, which may follow measles infection occurring early in life (<18 months of age). Persistence of the virus with reactivation pre-puberty results in accumulation of virus in the brain, progressive mental deterioration and a fatal outcome.

Maternal measles, unlike rubella, does not cause fetal abnormalities. It is, however, associated with spontaneous abortions and premature delivery.

Atypical measles

In the past, a severe illness called atypical measles occurred in individuals given an inactivated vaccine (now withdrawn). This vaccine conferred incomplete protection and on exposure to the wild measles virus they developed high fever, myalgia, abdominal pain and a variety of skin rashes which could be mistaken for scarlet fever, meningococcal disease or varicella. Pneumonia was invariably present and pulmonary infiltrates persisted for years in some cases.

Diagnosis and treatment

Most cases of measles are diagnosed clinically but, if necessary, immunofluorescence, virus culture and serological tests (complement fixation test (CFT), haemagglutination inhibition tests) are used to confirm the diagnosis.

Treatment is supportive. Antibiotics are indicated only if secondary bacterial infection occurs.

Prevention

A previous attack of measles confers a high degree of immunity and second attacks are uncommon. Normal human immunoglobulin given within 5 days of exposure effectively aborts an attack of measles. It is indicated for previously unimmunized children below 3 years of age, during pregnancy, and in those with debilitating disease.

Active immunization.

Children are immunized with the combined mumps-measles-rubella (MMR) vaccine