Interrupting herpes simplex virus type 2 transmission: the role of condoms and microbicides.

Condoms act as mechanical barriers to genital infection. In vitro models demonstrate that condoms are almost impermeable to viruses. A small amount of virus may cross the condom, but the condom can still reduce the level of virus exposure by several orders of magnitude. However, in vivo factors, such as condom failure during intercourse, can potentially limit their effectiveness. The weight of available evidence suggests that consistent and correct use of the male condom protects against herpes simplex virus (HSV) infection, as well as other sexually transmitted infections. Female condoms should theoretically protect against HSV infection as they cover a large surface area of potentially infected or susceptible tissues, but research is needed to confirm this. The lack of acceptance, or lack of consistent use, of condoms is the biggest barrier to their effectiveness. There is a need for effective counselling of individuals whose sexual behaviour increases their risk of HSV acquisition, such as young adults. Pregnant women are likely to be receptive to counselling due to the risk of neonatal herpes. No commercially available microbicides specifically inhibit HSV, although many inactivate the virus. More potent and specific microbicides are in development, but may be more expensive than those currently available. Although the effectiveness of condom and microbicide use is not completely proven, there is sufficient evidence to support the promotion of their use by healthcare professionals as an important part of safe sex counselling.