Roseola is a common disease of babies or young children, in which several days of very high fever are followed by a characteristic rash.
Roseola is an extraordinarily common infection, caused by a virus. About 90 percent of all children have been exposed to the virus, with about 33 percent actually demonstrating the syndrome of fever followed by rash.
The most common age for a child to contract roseola is between six and twelve months. Roseola infection strikes boys and girls equally. The infection may occur at any time of year, although late spring and early summer seem to be peak times for it.
Causes and symptoms
About 85 percent of the time, roseola is caused by a virus called human herpesvirus 6 (HHV-6). Although the virus is related to those herpesviruses known to cause sores on the lips or genitalia, HHV-6 causes a very different type of infection. HHV-6 is believed to be passed between people via infected saliva. A few other viruses (called enteroviruses) can produce a similar fever-then-rash illness, which is usually also called roseola.
Researchers believe that it takes about five to 15 days to develop illness after having been infected by HHV-6. Roseola strikes suddenly, when a previously well child spikes an impressively high fever. The temperature may reach 106°F (41°C) . As is always the case with sudden fever spikes, the extreme change in temperature may cause certain children to have seizures. About 5 to 35 percent of all children with roseola have febrile seizures.
The most notable thing about this early phase of roseola is the absence of symptoms, other than the high fever. Although some children have a slightly reddened throat or a slightly runny nose, most children have no symptoms whatsoever, other than the sudden development of high fever. This fever lasts for between three and five days.
Somewhere around the fifth day, a rash begins on the body. The rash is usually composed of flat pink patches or spots, although there may be some raised patches as well. The rash usually starts on the chest, back, and abdomen then spreads out to the arms and neck. It may or may not reach the legs and face. The rash lasts for about three days then fades.
Very rarely, roseola causes more serious disease. Patients so afflicted experience significant swelling of the lymph nodes, the liver, and the spleen. The liver may become sufficiently inflamed to interfere with its functioning, resulting in a yellowish color to the whites of the eyes and the skin (jaundice). This syndrome (called a mononucleosis-like syndrome, after the disease mononucleosis that causes many of the same symptoms) has occurred in both infants and adults.