rubella
The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.
DEFINITION:
- rubella
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A viral infection, also known as German measles (although the similarities to measles are few). Rubella causes a trivial illness in children and a slightly more troublesome one in adults. It is serious only when it affects a woman in the early months of pregnancy, when there is a chance that the virus will infect the fetus, which can lead to any of a range of severe birth defects, known as rubella syndrome.
CAUSES AND INCIDENCE:
Apart from mother-to-baby transmission, the rubella virus is spread from person to person in airborne droplets. Symptoms develop after an incubation period of two to three weeks.
Once common worldwide, rubella is now much less prevalent in most developed countries as a result of vaccination programs. The aim in the US has been to eradicate the virus by compulsory vaccination of all children before school entry; the results are encouraging. By 1986 the incidence in the US had been reduced to 551 reported cases of rubella and only 14 cases of rubella syndrome.
SYMPTOMS AND COMPLICATIONS:
The infection usually occurs between the ages of 6 and 12 and is almost invariably mild. A rash appears on the face, spreads to the trunk and limbs, persists for a few days, and then disappears. There may be a slight fever and enlargement of lymph nodes at the back of the neck. In some cases, the entire infection passes unnoticed. In adolescents and adults, there may be more marked symptoms, such as headache before the rash appears and a more pronounced fever. The virus may be transmitted to others from a few days before the symptoms appear until a day after they disappear. Polyarthritis (inflammation affecting several joints) is an occasional short-lived complication, starting shortly after the rash has faded.
CONGENITAL INFECTION:
Rubella is a risk to the unborn baby only if the mother is infected during the first four months of pregnancy. The earlier in pregnancy infection occurs, the more likely the infant is to be affected, and the more serious the abnormalities tend to be. In very early pregnancy, miscarriage may occur. An affected infant may have one or many defects. The most common abnormalities, in order of frequency, are deafness, congenital heart disease, mental retardation, cataract and other eye disorders, purpura, cerebral palsy, and bone abnormalities. About 20 percent of affected babies die in early infancy. An affected infant continues to harbor the virus and may infect others via his or her urine, stools, and saliva for a year or more after birth.
DIAGNOSIS AND TREATMENT:
Rubella is easily confused with other conditions such as rashes caused by other viruses, drugs, and scarlet fever. It can be positively diagnosed only by laboratory isolation of the virus from a throat swab or by tests to look for antibodies to the virus in the blood. There is no specific treatment for rubella. Acetaminophen can be given to reduce fever. Treatment of rubella syndrome is of the defects exhibited.
PREVENTION:
Rubella vaccine is highly effective in providing long-lasting immunity to the disease; it is given to all babies (usually combined with measles and mumps vaccine) at about 15 months of age. Reactions to the vaccine are usually negligible. Rubella infection itself also provides immunity.
Any female of childbearing age (or approaching it), who is unsure whether she has been immunized or has had rubella, should have her immune status checked. If she is not immune, vaccination is performed only if there is no chance that she is pregnant because of the risk of the vaccine causing rubella in the fetus.
A nonimmune pregnant woman must avoid contact with anyone who has rubella; if such contact occurs, she should immediately seek a physician's advice. Passive immunization with immune globulin may help prevent infection of the fetus.
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