Commonly acute, benign, viral illness characterized by fever with subsequent rash (see Incubation and duration of common rash-producing infections)

Affects infants and young children (typically from age 6 months to 3 years) and affects both sexes equally

Most commonly occurs in the spring and fall

Has an incubation period of 5 to 15 days

Also known as exanthema subitum

Human herpesvirus (HHV) type 6B replicates in leukocytes and in the salivary glands.

HHV-6 shows persistent and intermittent or chronic shedding in the normal population, resulting in the unusually early infection of children.

HHV-6 (most common)

May be transmitted by saliva, blood and, possibly, by genital secretions

Abruptly increasing, unexplainable fever peaking between 103° and 105° F (39.4° and 40.6° C) for 3 to 5 days and then dropping suddenly