Rubella (German Measles)

Rubella (German measles) is a common communicable infection of children and young adults characterized by a short prodromal period; enlargement of cervical, suboccipital, and postauricular glands; and a rash of approximately 2 to 3 days' duration. The disease has rare sequelae and, were it not for its devastating effect on the fetus, would be of relatively little significance in terms of morbidity or complications.

EPIDEMIOLOGY

Prior to immunization programs, epidemics of rubella were noted at 5- to 7-year intervals. The disease is worldwide in its distribution and tends to occur most frequently during the spring months in North America. During the past decade, fewer than 200 cases were reported in most years in the United States.  It is rare in young infants and is most common in school-age children, adolescents, and young adults. Recent outbreaks in North America have occurred in young men in Latino communities who have come from countries without immunization programs. Through these outbreaks, viruses that are common abroad have been introduced into the United States.  It is spread via the respiratory route, and the period of infectivity extends from the end of the incubation period to the disappearance of the rash. A single attack confers lifelong immunity in most individuals, although subclinical reinfections can be demonstrated by laboratory tests in some “immune” individuals who are subsequently exposed to the wild virus. Two attacks of rubella with rash are most unlikely to be encountered; in such instances, one of the episodes is usually not rubella but is caused by another viral infection.

The virus of rubella may be recovered from the pharynx as early as 7 days before and up to 14 days after the onset of the rash. Viremia is rarely demonstrated after the onset of the rash. 

CLINICAL MANIFESTATIONS

The incubation period ranges between 14 and 21 days and is usually 16 to 18 days. Prodromal signs and symptoms are rare in young children, and the rash usually appears without prior complaint. In older children, adolescents, and adults, low-grade fever, headache, conjunctivitis, sore throat, rhinitis, cough, and lymphadenopathy may precede the rash by 1 to 4 days and disappear rapidly after the rash appears. In some adults, however, these symptoms and signs may persist longer and be more severe, and the infection under such circumstances may be difficult to distinguish from rubeola (measles) unless Koplik's spots, characteristic of measles, are observed. The rash of rubella is first noted on the face  and rapidly spreads to the neck, arms, trunk, and legs. It consists of pink-red macules and papules that are discrete and remain so on the extremities, coalescing on the trunk to give a uniform red blush.

The rash, which usually disappears by the end of 2 or 3 days, clearing first from the face, may occasionally be followed by fine desquamation. This rapid disappearance is in contrast to measles (rubeola), in which the rash persists for longer periods. An enanthem is often seen at the end of the prodromal period or beginning of the rash, consisting of red spots, pinhead in size, scattered over the soft palate. The lymphadenopathy of rubella is striking; it involves all lymph nodes, but enlargement and tenderness are most common in the suboccipital, postauricular, and anterior and posterior cervical nodes. In older children and adults, lymphadenopathy may be noted several days before the rash; but in both children and adults, the enlargement and tenderness are most striking on the first day of the rash. Enlargement of glands may persist for days to weeks, but tenderness rapidly subsides. Splenomegaly may occasionally be detected. The fever of rubella is usually of low grade and seldom lasts beyond the first day or two of the eruption except in individuals who have joint involvement, in whom fever may persist. Arthritis caused by rubella occurs much more frequently in adults than in children, and is usually first noted as the rash fades. Small and large joints may become painful, with or without swelling, possibly simulating rheumatic fever or rheumatoid arthritis. In one epidemic, joint involvement was seen in 25 percent of children younger than 11 of years age and in 52 percent of patients 11 years of age or older. 4 Striking effusions into joints have been reported. The arthritis of rubella usually lasts 1 to 2 weeks but occasionally may persist for longer periods or may be recurrent.

COMPLICATIONS

Rubella is essentially a benign disease. Rarely, it may produce an encephalitis, which tends to be mild and is usually followed by complete recovery and no effect on intellectual function. Thrombocytopenic purpura, which may result from rubella, may be accompanied by epistaxis, petechiae, ecchymoses, intestinal hemorrhage, and hematuria. These manifestations frequently clear within a month of onset but may occasionally persist for longer periods. Rarely, a peripheral neuritis may follow rubella.

LABORATORY FINDINGS

The white blood cell count is usually low but may be normal. Increased numbers of atypical lymphocytes may be noted, and in some cases, increased numbers of plasma cells have been reported. Among patients with meningoencephalitis, varying numbers of lymphocytes may be found in the cerebrospinal fluid (CSF).