CHILDHOOD EXANTHEMS: Rubella

Introduction

Exanthems are a common cause of generalized rashes in children. They pose a diagnostic challenge to even the most experienced physician because of the diversity of their clinical presentations. The morphology distribution, and associated signs and symptoms are sometimes specific enough for a definitive diagnosis, but, nonspecific clinical findings often make this impossible. Advances in laboratory techniques (particularly in viral diseases), new antiviral drugs and vaccines, epidemics of old exanthems, and the recognition of new clinical syndromes have stimulated renewed interest in exanthems. Historically, exanthems were numbered in the order in which they were first differentiated from other exanthems. Thus, "first" disease was measles (rubeola), "second" disease was scarlet fever, and "third" disease was rubella (German measles). The specific disease described as "fourth" disease, so-called Pilatov-Dukes disease, is no longer accepted as a distinct clinical entity, with some authors speculating that it represented staphylococcal scalded skin syndrome, and others speculating that it was concurrent infection with both scarlet fever and rubella. Fifth disease is erythema infectiosum, and sixth disease is roseola infantum. Only in the last decade, with the identification of parvovirus B19 as the cause of erythema infectiosum and human herpesvirus 6 as the cause of roseola infantum, have the causative agents of the classic exanthems been identified.

Rubella

Rubella is also known as German Measles or Three-Day Measles.  Rubella is a contagious viral disease characterized by swelling of Iymph glands and a rash. A pregnant woman infected with rubella during the early months of pregnancy may develop an abortion, stillbirth or congenital defects in the infant.

 

Symptoms

Rubella has a 14- to 21-day incubation period and a 1- to 5-day preliminary phase in children. The preliminary phase may be minimal or absent in adolescents and adults. Tender swelling of the glands in the back of the head, the neck and behind the ears is characteristic. The typical rash appears days after onset of these symptoms. The rubella rash is similar to that of measles, but it is usually less extensive and disappears more quickly. It begins on the face and neck and quickly spreads to the trunk and the extremities. At the onset of the eruption, a flush similar to that of scarlet fever may appear, particularly on the face. The rash usually lasts about three days. It may disappear before this time, and rarely there is no rash at all. A slight fever usually occurs with the rash. Other symptoms such as headache, loss of appetite, sore throat and general malaise, are more common in adults and teenagers than in children. After-effects of rubella are rare among children, although there have been cases of joint pain (arthralgia), sleeping sickness and blood clotting problems. Adult women who contract rubella are often left with chronic joint pains. Encephalitis is a rare complication that has occurred during extensive outbreaks of rubella among young adults serving in the armed services. Transient pain in the testes is also a frequent complaint in adult males with rubella.

 

Cause

Rubella is caused by an RNA virus of uncertain classification (probably a toga-virus), and is spread by airborne droplet clusters or by close contact with an infected person. A patient can transmit the disease from 1 week before onset of the rash until 1 week after it fades. Congenitally infected infants are potentially infectious for a few months after birth. Rubella is apparently less contagious than measles, and many persons are not infected during childhood. As a result, 10% to 15% of young adult women are susceptible if they have not been vaccinated against the disorder. Many cases are misdiagnosed or go unnoticed. Before the rubella vaccine was developed, epidemics occurred at regular intervals during the spring. Major epidemics occur at about 6 to 9 year intervals. Once infected by rubella, immunity appears to be lifelong.

 

Similar Disorders

Measles, scarlet fever (scarlatina), secondary syphilis, drug rashes, erythema infectiosum (fifth disease), infectious mononucleosis, and echo-, coxsackie- and adenovirus infections must be considered in the differential diagnosis. Rubella is clinically differentiated from measles by the milder rash that disappears faster, and by the absence of the small, irregular, bright red spots (Koplik's spots) on the mucous membranes inside of the cheeks and on the tongue, a running nose (coryza), the aversion to light, and a cough. A patient with measles appears more sick, and the illness lasts longer. With even mild scarlet fever (scarlatina), there are usually more constitutional symptoms than in rubella, including a severely red, sore throat. The white blood cell count is elevated in scarlet fever, but is usually normal in rubella. The rash and swollen Iymph nodes (adenopathy) of rubella can be simulated by secondary syphilis. However, the Iymph nodes are not tender in syphilis and the rash appears bronze-like. If there is doubt, a quantitative serologic test for syphilis can be performed. Infectious mononucleosis may also cause a rubella-like swelling of Iymph nodes and a skin rash, but can be differentiated by the initial lack of white blood cells (leukopenia) followed by an increase in white blood cells (leukocytosis). Many typical mononuclear cells appear in the blood smear, with appearance of antibodies to the Epstein-Barr virus. In addition, the sore throat of infectious mononucleosis is usually prominent, and malaise is greater and lasts much longer than in rubella. A clinical diagnosis of rubella is subject to error without laboratory confirmation, especially since many viral rashes closely mimic rubella. Acute and convalescent serum should be obtained, if possible, for serologic testing. A 4-fold or greater rise in specific hemagglutination inhibiting antibodies confirms the diagnosis of rubella.

 

Therapy

Standard  Therapies: Prevention is the most important therapy. The purpose of rubella immunization programs is to prevent some of the catastrophes associated with congenital rubella. All children between the ages of 15 months and puberty should be routinely vaccinated against rubella. Women of childbearing age whose blood tests negative for rubella hemagglutination inhibiting antibodies should be immunized. Conception should be prevented for at least 3 months after immunization. Rubella, itself, requires little or no treatment. Middle ear infection (otitis media), a rare complication, is usually treated with penicillin or other antibiotic.