HSV asymptomatic shedding occurs at some time in most individuals infected with herpes. It can occur more than a week before or after a symptomatic recurrence in 50% of cases. Virus enters into susceptible cells by entry receptors such as nectin-1, HVEM and 3-O sulfated heparan sulfate. Infected people who show no visible symptoms may still shed and transmit viruses through their skin; asymptomatic shedding may represent the most common form of HSV-2 transmission. Asymptomatic shedding is more frequent within the first 12 months of acquiring HSV. Concurrent infection with HIV increases the frequency and duration of asymptomatic shedding. Some individuals may have much lower patterns of shedding, but evidence supporting this is not fully verified; no significant differences are seen in the frequency of asymptomatic shedding when comparing persons with one to 12 annual recurrences to those with no recurrences.
Varicella-zoster is transmitted though the mucosa of the respiratory system, specifically the upper respiratory tract, or the conjunctiva of the eye. Initial replication takes place in the regional lymph nodes, and then the virus spreads and replication begins in the liver and spleen. The virus is then transported to the skin where the rash develops. The incubation period of varicella is about 10 to 21 days.
A 2004 study in the New England Journal of Medicine found that suppressive therapy decreases the risk of HSV-2 transmission from symptomatic, infected partners to uninfected partners by 48%. So “the risk of transmission is significantly reduced, but cannot be eliminated even with suppressive therapy,” Johnston explains, and she stresses that the virus can be passed along even without signs or symptoms.