How is human herpesvirus 6 spread?
Human herpesvirus 6
Transmission is believed to occur most frequently through the shedding of viral particles into saliva. Both HHV-6B and HHV-7 are found in human saliva, the former being at a lower frequency. Studies report varying rates of prevalence of HHV-6 in saliva (between 3–90%), and have also described the salivary glands as an in vivo reservoir for HHV-6. The virus infects the salivary glands, establishes latency, and periodically reactivates to spread infection to other hosts.
Human herpesvirus 6
"Herpesvirus" was established as a genus in 1971 in the first report of the ICTV. This genus consisted of 23 viruses among 4 groups. In 1976, a second ICTV report was released in which this genus was elevated to the family level — the "herpetoviridae". Because of possible confusion with viruses derived from reptiles, the family name was changed in the third report (1979) to "herpesviridae". In this report, the family "Herpesviridae" was divided into 3 subfamilies ("alphaherpesvirinae", "betaherpesvirinae" and "gammaherpesvirinae") and 5 unnamed genera; 21 viruses were recognized as members of the family.