Symptoms
Three-day fever is most common in infants 6-12 months of age and in young children. Newborns are still protected thanks to maternal antibodies. After an incubation period of 5-15 days, the disease begins with sudden onset and high fever that lasts for 3-5 days. Febrile convulsions are a known and comparatively frequent complication (about 10%). Rarely, encephalitis may occur and other accompanying symptoms may be present. After the fever subsides, a minority of children present with a mild, pink maculopapular rash beginning on the trunk and neck and usually not pruritic, which subsequently spreads to the arms and legs and quickly disappears. The face is usually unaffected or only mildly affected. The disease may also be asymptomatic and the rash does not necessarily follow the fever. If immunosuppression is present, reactivation in adulthood is possible with a severe course and involvement of various organs. If the initial illness occurs in adulthood, it results in a disease resembling infectious mononucleosis (glandular fever).
Causes
Three-day fever is a viral infectious disease caused by human herpesvirus 6B and 7 (HHV-6B, HHV-7). The enveloped DNA viruses belong to the Herpesviridae family and to the same subfamily as cytomegalovirus. HHV replicates in immune cells and salivary glands, among other places, and is found in saliva. Virtually all people were infected as children and are seropositive.
Transmission
Like other herpes viruses, HHV remains latent in the body. After passing through the disease, affected individuals are immune for life but continue to excrete the virus in small amounts. Transmission likely occurs through saliva from the mother and father, other adults, or other children to infants.
Diagnosis
Diagnosis is made in pediatric care based on the clinical picture and laboratory methods. If there is no rash, diagnosis is difficult based on symptoms. Other pediatric diseases associated with a rash must be ruled out. Possible differential diagnoses include allergic reactions, the measles, rubella, and scarlet fever.
Treatment
Bed rest and adequate hydration are recommended. Fever should be measured regularly. Three-day fever is usually benign and passes on its own. Treatment is symptomatic with antipyretics such as acetaminophen, which is available for children as syrup, drops, or suppositories. In case of complications, specific and possibly emergency medical treatment is required (e.g., febrile convulsions). Antiviral drugs such as ganciclovir, valganciclovir, foscarnet, and cidofovir are used only in a severe course in immunocompromised individuals. They are not approved for this indication (off-label).
