Telling people to always wear condoms during intercourse if they don't
know their partner's HIV status or are half of a sero-discordant couple
(when one partner is HIV-positive and the other is HIV-negative) is a
successful prevention strategy. The chance of infection increases with repeated acts of intercourse
(more exposure to the virus), yet the risk of transmission in any one
sexual episode differs. For instance, transmission is more likely when
there is an increased amount of virus in genital fluids or blood (a high
viral load) than when the viral load is lower.
