Fifth disease is a viral infection which causes a very typical rash in children and adults. It is caused by human parvovirus B19. Fifth disease was so named because it was the fifth pink-red infectious rash to be described by physicians years ago, before those diseases were renamed. For those history buffs out there, the other four diseases are:
- Scarlet Fever
- Filatov-Dukes disease
Fifth Disease usually begins as a bright red or rosy rash on both cheeks which lasts for 1 to 3 days. Some people say that the rash gives a child a “slapped cheek” appearance. The rash on cheeks is followed by pink “lacelike” rash on the extremities as if the child had been laying on lace for some time. This “lacey” rash mainly appears on the thighs and upper arms. It appears and disappears several times over a 1 to 5 week period. It is especially prominent after warms baths, exercise, and sun exposure. Usually the child has no fever or only a low-grade fever (less than 101 F) with fifth disease. This is a very mild disease with either no symptoms or a slight runny nose and sore throat. No treatment is generally necessary.
Fifth disease is contagious. Over 50% of exposed children will come down with the rash in 10 to 14 days. Because the disease is mainly contagious during the week before the rash begins, a child who has the rash is no longer contagious and does not need to stay home from school or daycare.
Most adults who get fifth disease develop just mild pinkness of the cheeks or no rash at all. In addition to the mild rash, adults can develop joint pains, especially in the knees. These pains may last 1 to 3 months. Taking ibuprofen usually relieves these symptoms. An arthritis workup is not necessary for joint pains that occur after exposure to fifth disease.
The main risk of fifth disease is to pregnant women who are not immune to the disease. Research has shown that 10% of unborn babies whose mothers are not immune to fifth disease who are subsequently infected with the virus before birth, may develop severe anemia or even die. This is especially true of the first 3 months of pregnancy. This virus, however, doesn’t cause any birth defects. If you are pregnant and exposed to a child with fifth disease before the child develops the rash, see your obstetrician. He or she will may get a sample of your blood for an antibody test to see if you already have had the disease and are protected from becoming infected again. If you do not have antibodies against fifth disease, your pregnancy will need to be monitored closely.