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"Fifth disease' is common and marked by bright rash

Parents are happy to get another winter season, with its cold and flu, behind them. They look forward to spring and an end to runny noses and coughs. Just when it seems safe to put away decongestants and tissues, along comes "fifth disease," a viral infection frequently seen this time of year.

When given the diagnosis of fifth disease, most people looked puzzled. Probably they have never heard it, even though it was first described more than a century ago. It earned its name by being the fifth disease in a group of newly discovered illnesses that caused rashes _ measles, Rubella (German measles), roseola and scarlet fever.

Doctors sometimes like to justify all the Latin we had to take in college, so we have given fifth disease a more complicated name: erythema infectiosum ("infectious redness"). Although most medical encyclopedias and dictionaries still do not have listings for it, fifth disease is a common childhood illness. The Centers for Disease Control and Prevention estimates that 15 percent to 60 percent of children ages 5 to 19 have had the disorder, and up to 50 percent of adults have been infected with it at some time.

Fifth Disease is caused by the human parvovirus B19 and is spread by respiratory secretions from coughing and sneezing. The incubation period usually is between four and 14 days after exposure. Occasionally, the illness begins with flulike symptoms consisting of sore throat, muscle aches, loss of appetite and a profuse nasal discharge. These symptoms commonly are present about two days before the onset of a rash.

The rash of fifth disease usually occurs in three stages. Beginning on the face, it produces an impressive, intensely red rash raised and warm to the touch, the "slapped cheek" appearance. After one to three days, a pink, lacelike rash appears, mainly on the thighs and upper arms. During the third stage, which can last one to three weeks, the lacy rash comes and goes, fluctuating in intensity with heat, exercise and exposure to the sun. Fever usually is absent. If there is fever, it usually is less than 102 degrees. One bout of fifth disease apparently gives lifetime immunity against having it again. No treatment is necessary.

The distinctive rash is harmless. In some children, the rash is made worse by bathing, exercise or sun exposure, so avoiding these may be helpful. The rash sometimes can be confused with other medical conditions, especially allergic reactions to medications or foods.

Children are contagious about a week before developing the illness; once the rash appears, they no longer are contagious. It is illogical to keep a child with fifth disease from attending school or day care since they can no longer pass the illness on to others.

Fifth disease is just an annoying affliction in children. Five years ago, it was discovered that pregnant women who catch the disease during the first trimester suffer an increased risk of miscarriage (3 to 5 percent). During the later months of pregnancy, the disease can also cause a dangerous type of fetal anemia. Fortunately, the risks of such complications are small (less than 2 percent), even during epidemics of fifth disease.

No reports of birth defects have ever been associated with fifth disease. The American Academy of Pediatrics suggests that a pregnant woman who has been in contact with a child who has fifth disease should inform her obstetrician.

Then, if appropriate, frequent ultrasound examinations and blood tests can be done to monitor fetal development. An antibody test may soon be readily available so mothers-to-be can know whether they are protected from the virus. The risk to expectant mothers who have never had the disease is very low, although the academy recommends close follow-up care for pregnant women who are exposed to a child with fifth disease. Women who have had fifth disease before becoming pregnant do not need to worry at all.

Bruce A. Epstein has practiced pediatrics in St. Petersburg since 1973. He is a member of the American Academy of Pediatrics.