A primary infection of Human Herpes virus 6 usually occurs at the age of 6 – 18 months, the virus is symptomatic in 90 percent of children, fever is a symptom that mainly occurs with an infection of HHV 6. HHV 6 causes the childhood illness roseola infantum, also called the sixth disease.
to what extent HHV7 causes infection in humans is still unclear. In most cases, an infection with HHV7 is asymptomatic. Possible symptoms that HHV7 can cause are fever, diarrhea and vomiting. HHV6 and HHV7 are related to each other, leading to serological cross-reactivity. Only a certain number of monoclonal antibodies are type-specific.