Is scarlet fever dangerous to unborn children? My granddaughter was diagnosed with scarlet fever, but before we were told, my daughter had kissed her. My daughter is 12 weeks pregnant, and we cannot find any medical articles that cover this.

J.P.

There is a lot of confusion regarding scarlet fever. Scarlet fever is the name given to a syndrome consisting of streptococcal pharyngitis (strep throat) and, rarely, streptococcal skin infections that are complicated by a sunburnlike rash. The syndrome occurs when the infecting agent, the bacterium Streptococcus pyogenes, produces a toxin. In most cases, the rash begins a day or two after the sore throat. It is a diffuse, red blush that usually does not involve the face or the palms and soles. Skin folds can appear a deeper red. There are various changes of the tongue, which have been termed "white-and-red strawberry tongue."

Usually, scarlet fever is not much more severe than the usual strep throat. The illness will typically resolve without treatment, but medication, usually penicillin, can shorten the duration of illness. Treatment also prevents the most serious complication of strep throat, acute rheumatic fever, a disease uncommon in the United States at present.

As far as the effect on your daughter's unborn child -- there should usually be none. First, your daughter probably did not even develop a strep infection, as the disease is not nearly as contagious as other infections. Second, even if she does get strep throat, she may not get scarlet fever, because some people develop immunity to the toxin. Third, even if she does get scarlet fever, it can promptly be treated, preventing any serious complications in her or in her baby.