Prognosis
Children infected with roseola generally have a good prognosis. Most recover without intervention and without long-term effects. Epidemiology
Between the two types of human herpesvirus 6, HHV-6B has been detected much more frequently in hosts. HHV-6B has been shown to affect about 90% of children before the age of 3. 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 the ages of 6 months and 12 months who have fever, twenty percent of these are due to HHV-6.Many children who have been 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.
Signs and symptoms
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. However, many children in the febrile phase feel well, engaged, and alert. For these patients, fever is usually diagnosed incidentally.The most common complication (10-15% of children between 6 and 18 months) and most common cause of hospitalization in children with primary infection of HHV-6B is febrile seizures which can precipitate status epilepticus due to the sudden rise in body temperature. Rash
Once the febrile phase subsides, a rash develops. In some cases, the rash can present after one or two days after the fever resolves. The rash is classically described as an erythematous morbilliform exanthem and presents as a distribution of soft pink, discrete, and slightly raised lesions each with a 2-5mm diameter. It classically begins on the trunk (torso) and spreads outward to the neck, extremities, and face. This pattern is referred to as a centrifugal spread. Usually, peeling and itching are not characteristic of this rash. This phase can last anywhere from several hours to 2 days. Other symptoms
A small percentage of children acquire HHV-6 with few signs or symptoms of the disease. Children with HHV-6 infection can also present with myringitis (inflammation of the tympanic membranes), upper respiratory symptoms, diarrhea, and a bulging fontanelle. In addition, children can experience pharyngitis with lymphoid hyperplasia seen on the soft palate and swelling of the eyelids. These symptoms usually present during the febrile phase of roseola.