query: How is human herpesvirus 6 spread?
passage: 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%),[13] 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.[23]
passage: Human alphaherpesvirus 3
There are five principle clades (1–5) and four genotypes that do not fit into these clades. The current distribution of these clades is Asia (clades 1,2, and 5) and Europe (clades 1, 3 and 4). Allocation of VZV strains to clades required sequence of whole virus genome. Practically all molecular epidemiological data on global VZV strains distribution obtained with targeted sequencing of selected regions.