Roseola infantum occurs throughout the year, most often in the spring and fall. Sometimes minor local outbreaks occur. The usual cause is herpesvirus-6, one of the many human herpesviruses. Most children who develop roseola infantum are between 6 months and 3 years of age.
Roseola infantum symptoms begin about 5 to 15 days after infection. A fever of 103 to 105° F (about 39.5 to 40.5° C) begins abruptly and lasts for 3 to 5 days. In 5 to 15% of children, seizures occur as a result of high fever, particularly as the fever begins and rises quickly. Despite the high fever, the child is usually alert and active. A few children have a mild runny nose, sore throat, or an upset stomach. The lymph nodes at the back of the head, the sides of the neck, and behind the ears may be enlarged. The fever usually disappears on the fourth day.
About 30% of children with roseola infantum develop a rash within a few hours to, at most, a day after the temperature falls. The rash is red and flat. It occurs mostly on the chest and abdomen and less extensively on the face, arms, and legs. The rash is not itchy and may last from a few hours to 2 days.
Fever is treated with acetaminophen or ibuprofen. The seizures and rash do not require any specific treatment, but because they are frightening, most parents bring their child to the doctor for evaluation.
If the disease is severe in children with a weakened immune system, doctors may try treating them with the antiviral drugs foscarnet or ganciclovir.