Sex in the city: sexual behaviour, societal change, and STDs in Saigon.

HIV infection is increasing among sex workers and injection drug users in southern Vietnam. Vietnamese sex workers returning from Cambodia are an important factor. This phase I growth stage is being accelerated by widespread prostitution and escalating heroin use. Sexually transmitted disease (STD) rates are significant in sex workers but low in the general population. STD epidemics in developing countries may not follow the dynamic topology that is common in developed countries. Vietnam has the potential for significant HIV and STD epidemics but also the capacity to respond to these threats.