Cumulative probability of HIV transmission over multiple sexual exposures for all females (a). The lower line is the risk if all exposures involve vaginal intercourse. The upper line is the risk if all exposures involve HAI. The red line is the risk if 10% of exposures involve HAI. The risk females acquire HIV each year (b). Females in general population with a HIV-positive regular partner assumed to have 100 sexual acts per year. HIV incidence rate in females in general population (c). Red part of each bar represents the increase in incidence due to HAI.