FIFTH'S DISEASE (Erythema Infectiosum)
Fifth's disease is an infection that is caused by the Parvo B19 virus. It was so named because it was the fifth major childhood skin rash that was seen regularly(behind scarlet fever, measles and rubella...there is no fourth). It tends to occur in epidemics, often in the late winter to early spring. Children 4-7 years old are the most common target, but the virus can affect adults. In adults, it can cause arthritis-like symptoms, and can adversely affect the baby in a pregnant mother's womb(hydrops). Immunocompromised people can develop anemia upon exposure to Parvo B19.
Fifth's disease often begins with headache and malaise(feeling yucky). A slapped-face appearance then appears on the face and spreads to the extremities and trunk. As it fades it leaves a lacy appearance on the extremities. The patient usually feels better as the rash appears. It may recur over the next 7-10 days, often after exposure to sunlight or a warm bath. By the time the rash appears, the child is no longer contagious.
The virus is spread through respiratory droplets, much like the common cold. Symptoms occur 4-28 (usually about 10) days after exposure. Since the infectious period is over by the time the rash occurs and the diagnosis is made, it is not practical to try to keep the infected person away from others. It is, however, valuable to contact immuno-compromised and pregnant people who have been exposed to the infected person.
Blood tests can be helpful, but because of their expensive, are usually limited to difficult cases and exposures to pregnant and immuno-suppressed patients. IgM levels rise by 3 days, IgG by 3 weeks, and PCR tests are available.
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