Roseola is a common infectious (viral) disease of young children, in which several days of very high fever are followed by a rash. Most children are exposed to the virus but only 33 percent actually develop illness. The most common age for a child to contract roseola is between 6 months and 2 years. Roseola infection strikes boys and girls and the infection may occur at any time of year.

The viral diseases roseola and fifth disease are somewhat similar in terms of their presentation, but they are caused by different viruses. Roseola, sometimes called roseola infantum or exanthem subitum (“sudden rash”), is a mild viral infection usually caused by human herpesvirus-6 (HHV-6) and occasionally by HHV-7. It is spread via direct contact with the saliva or respiratory secretions of an infected individual, often through droplet aerosols. Roseola is very common in children, with symptoms including a runny nose, a sore throat, and a cough, along with (or followed by) a high fever (39.4 ºC). About three to five days after the fever subsides, a rash may begin to appear on the chest and abdomen. The rash, which does not cause discomfort, initially forms characteristic macules that are flat or papules that are firm and slightly raised; some macules or papules may be surrounded by a white ring. The rash may eventually spread to the neck and arms, and sometimes continues to spread to the face and legs. The diagnosis is generally made based upon observation of the symptoms. However, it is possible to perform serological tests to confirm the diagnosis. While treatment may be recommended to control the fever, the disease usually resolves without treatment within a week after the fever develops. For individuals at particular risk, such as those who are immunocompromised, the antiviral medication ganciclovir may be used.

Fifth disease (also known as erythema infectiosum) is another common, highly contagious illness that causes a distinct rash that is critical to diagnosis. Fifth disease is caused by parvovirus B19, and is transmitted by contact with respiratory secretions from an infected individual. Infection is more common in children than adults. While approximately 20% of individuals will be asymptomatic during infection, others will exhibit cold-like symptoms (headache, fever, and upset stomach) during the early stages when the illness is most infectious. Several days later, a distinct red facial rash appears, often called “slapped cheek” rash (figure). Within a few days, a second rash may appear on the arms, legs, chest, back, or buttocks. The rash may come and go for several weeks, but usually disappears within seven to twenty-one days, gradually becoming lacy in appearance as it recedes.

In children, the disease usually resolves on its own without medical treatment beyond symptom relief as needed. Adults may experience different and possibly more serious symptoms. Many adults with fifth disease do not develop any rash, but may experience joint pain and swelling that lasts several weeks or months. Immunocompromised individuals can develop severe anemia and may need blood transfusions or immune globulin injections. While the rash is the most important component of diagnosis (especially in children), the symptoms of fifth disease are not always consistent. Serological testing can be conducted for confirmation.

The most common cause of roseola is a virus called Human Herpes virus 6, or HHV-6. HHV-6 is believed to be passed between people by respiratory secretions, for example, coughing and sneezing. A few other viruses (called enteroviruses) can produce a similar fever followed by a rash illness, which is usually also called roseola. It takes about five to fifteen days to develop illness after being infected.

Roseola strikes suddenly, when a previous well child spikes a very high fever. Some children may have “febrile seizures” with sudden fever spikes. Although some children have a slightly reddened throat, irritability or a slight runny nose, most children have no symptoms other than the sudden development of a high fever. This fever may last for three to five days. Somewhere around the fifth day, a rash begins on the body. The rash is usually composed of flat pink or discolored patches or spots, although there may be some raised patches as well. The rash usually starts on the chest, back and abdomen and then spreads out to the arms and neck. It may not reach the legs and face. The rash lasts for about three days, then fades. The child may have “sleepy” or “droopy” eyelids. Very rarely, roseola will cause more serious disease.

The diagnosis of roseola is often made by carefully examining the feverish child. Once it is determined that pneumonia, ear infection, strep throat or other common childhood illness are not present, the health care provider usually feels comfortable waiting to see if the characteristic rash of roseola begins.

There are no treatments available. Most children recover quickly and completely from roseola. Acetaminophen or ibuprofen may be given to lower the fever. Aspirin should not be given to children under age 20 without a health care provider’s approval, due to the increased risk of developing Reye's Syndrome. Children may return to childcare after fever is gone for 24 hours. Children recover quickly and completely from roseola.

Other than the usual good hygiene practices, no methods are available to prevent roseola.