Roseola

Fever Symptoms begin with a three to six-day febrile illness. During this time, temperatures can peak above 40 °C and children can experience increased irritability with general malaise. Rash Once the febrile phase subsides, a rash develops. The rash sometimes presents one or two days after the fever resolves. Other symptoms A small percentage of children acquire HHV-6 with few signs or symptoms of the disease. diarrhea, and a bulging fontanelle. In rare cases, HHV-6 can become active in an adult previously infected during childhood and can show signs of mononucleosis. ==Cause==

There are nine known human herpesviruses. Of these, roseola has been linked to two: human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7), which are sometimes referred to collectively as Roseolovirus. After infection, these viruses enter a latent phase. Roseola caused by HHV-7 has been linked to the ability of HHV-7 infection to reactivate latent HHV-6. Even so, most cases of roseola are transmitted without known exposure. == Diagnosis ==

The diagnosis of roseola is made clinically based on the presence of the two phases: fever and rash. Laboratory testing is seldom used as the results do not alter the management of the disease. An exception is in people who are immunocompromised in whom serologic tests with viral identification can be used to confirm the diagnosis. Roseola should be differentiated based on symptoms from other similar-appearing illnesses, such as rubella, measles, fifth disease, scarlet fever, and drug reactions. ==Prevention==

Many viruses can cause roseola and are shed by carriers without symptoms. Because of this and the fact that most children with the disease are not seriously ill, there is no particular method of prevention. ==Treatment==

Most cases of HHV-6 infection improve on their own. Because of this, supportive care is the mainstay treatment. The febrile phase can be managed using acetaminophen to control fever and prevent spikes in temperature which can lead to febrile seizures. Treatment of children who are immunocompromised centers around decreasing their levels of immunosuppression as much as possible. == Prognosis ==

Children infected with roseola generally have a good prognosis. Most recover without intervention or long-term effects. == Epidemiology ==

Between the two human herpesvirus 6 types, HHV-6B has been detected much more frequently in hosts. Out of these, 20% develop symptoms of roseola, also known as exanthem subitum. Roseola affects girls and boys equally worldwide year-round. Roseola typically affects children between six months and two years of age, with peak prevalence in children between 7 and 13 months old. This correlates with the decrease in maternal antibodies, thus virus protection, that occurs at the age of 6 months. Out of all emergency department visits for children between ages 6 months and 12 months who have a fever, twenty percent of these are due to HHV-6. Many children exposed and infected can present without symptoms, which makes determining the incidence within the population difficult. ==History==

John Zahorsky MD wrote extensively on this disease in the early 20th century, his first formal presentation was to the St Louis Pediatric Society in 1909 where he described 15 young children with the illness. In a JAMA article published on Oct 18, 1913, he noted that "the name 'Roseola infantilis' had an important place in the medical terminology of writers on skin diseases" but that descriptions of the disease by previous writers tended to confuse it with many other diseases that produce febrile rashes. In this JAMA article, Zahorsky reports on 29 more children with roseola and notes that the only condition that should seriously be considered in the differential diagnosis is German measles (rubella) but notes that the fever of rubella only lasts a few hours whereas the prodromal fever of roseola lasts three to five days and disappears with the formation of a morbilliform rash. ==Names==

HHV-6 has been tentatively linked with neurodegenerative diseases. == See also ==