Roseola Infantum Roseola infantum occurs throughout the year, sometimes in local outbreaks. The usual cause is herpesvirus 6, one of the many human herpesviruses. Most children who develop roseola infantum are between 6 months and 3 years of age.
Three Day Fever The disease also has other names; Roseola infantum, exanthematous fever, and three-day-rash. Although most small children catch it, it is one of the lesser-known children's diseases that causes a rash. It is only seen in children from the age of six months to three years and it is highly contagious.
What is Roseola Virus? Roseola is an infectious virus that many infants under three years old can catch, but is most common in infants under age one. Roseola is thought to be caused by the human herpes virus six.