Shedding of herpes simplex virus type 1 into tears and saliva in healthy Japanese adults.

It is well known that asymptomatic viral shedding is one of the forms of reactivation of herpes simplex virus type-1 (HSV-1). Although there have been some long-term investigations of viral shedding into tears and saliva in healthy subjects in the U.S.A, there have previously been no investigation study in Japan. Racial differences in the incidence of reactivation of HSV-1 have been pointed out, and it has been considered that reactivation is found less often among Japanese people than among Westerners. In the present study, we selected 10 healthy adults (7 males and 3 females) to isolate HSV-1 from tears and saliva 3 times a week over 6 months, and the results were compared with the results of other studies conducted in the U.S.A. It was found that the virus was isolated in 5 (3 males and 2 females) of 10 subjects and of the 5 subjects, the virus was isolated from saliva in 4 and from tears in 1. The number of specimens was 1,742 for tears and 871 for saliva with isolation of 1 and 4, respectively. The duration of shedding was only 1 day in all of the 5 subjects in whom the virus was isolated. The isolation frequency was significantly lower among Japanese people than among American people when our results were compared with the results of studies conducted in the U.S.A. It was clear that the reactivation rate was lower for Japanese people in terms of asymptomatic shedding.