Also Known As: Roseola, Exanthema subitum, Roseola infantum, Sixth disease, Baby measles, Three-day fever
Exanthema subitum (meaning sudden rash), also referred to as roseola infantum (or rose rash of infants), sixth disease (as the sixth rash-causing childhood disease), and (confusingly) baby measles, or three-day fever, is a disease of children, generally under two years old, although it has been known to occur in eighteen-year-olds, whose manifestations are usually limited to a transient rash ("exanthem") that occurs following a fever of about three day's duration.
It is caused by two human herpesviruses, HHV-6 (Human herpesvirus 6) and HHV-7, which are sometimes referred to collectively as Roseolovirus. There are two variants of HHV-6 (HHV-6a and HHV-6b) and studies in the US, Europe, Dubai and Japan have shown that exanthema subitum is caused by HHV-6b. This form of HHV-6 infects over 90% of infants by age 2. Research has shown that babies can be congenitally infected with HHV-6 via vertical transmission. This has been shown to occur in 1% of births in the United States. It has a peak presentation between 3-4 years of age.
Typically the disease affects a child between six months and two years of age, and begins with a sudden high fever (39–40 °C; 102.2-104 °F). This can cause, in rare cases, febrile convulsions (also known as febrile seizures or "fever fits") due to the sudden rise in body temperature, but in many cases the child appears normal. After a few days the fever subsides, and just as the child appears to be recovering, a red rash appears. This usually begins on the trunk, spreading to the legs and neck. The rash is not itchy and may last 1 to 2 days. In contrast, a child suffering from measles would usually appear more infirm, with symptoms ofconjunctivitis, coryza, and a cough, and their rash would affect the face and last for several days. Liver dysfunction can occur in rare cases.
There is no specific vaccine against or treatment to date for exanthema subitum, and most children with the disease are not seriously ill. A child with fever should be given plenty of fluids to drink.Paracetamol/acetaminophen or ibuprofen could be given to reduce their temperature (but neveraspirin, due to the risk of Reye's Syndrome).
A small percent of children acquire HHV-6 "subclinically"; in other words, they show no outward sign of the disease. Exanthema subitum occurs in approximately 30% of children during primary HHV-6 infection. Others may be debilitated enough that a doctor's opinion is required to confirm the diagnosis, and particularly to rule out other more serious infections, such asmeningitis or measles. In case of febrile seizures, medical advice is essential.
For HHV-6 infection, no pharmacological treatments have been approved as of June 2012. Although they may be unnecessary for exanthema subitum, the usage of Cytomegalovirus treatments (valganciclovir, ganciclovir, cidofovir, and foscarnet) have shown some success. These drugs are given with the intent of inhibiting proper DNA polymerization by competing with deoxy triphosphate nucleotides or specifically inactivating viral DNA polymerases.