PIP: Since simple quantitative measures of levels of infectious virus in blood, semen, and cervical secretions do not exist, the medical community does not yet understand the biological factors that determine both infectivity of and susceptibility to sexually transmitted HIV infection. A prospective study of female prostitutes and clients in Kenya shows that genital ulcer disease (GUD) especially chancroid was a very strong risk factor for HIV seroconversion (relative risk=4.7). The presence of a GUD also facilitated transmission. Yet a cohort study in Kinshasa, Zaire demonstrates that GUD prevalence was only 5% and of 55 women who seroconverted over 2 years, just 4 had a GUD before seroconversion. Another study of female prostitutes in Kinshasa finds that the nonulcerative sexually transmitted diseases (STDs) chlamydiasis, gonorrhea, and trichomoniasis were also strongly related to HIV seroconversions (odds ratios=5, 3.5, and 1.9, respectively). Other research indicated that HIV infection influences STDs. For example, several case reports indicate that HIV infection causes more frequent progression to neurosyphilis, an atypical clinical presentation of syphilis, poor response to standard therapy, and high numbers of false negative and false positive serologic tests. These studies did not use a comparative HIV negative group, however. A study of 116 homosexual men shows a significantly greater mean number of recurrences of anal warts in HIV positive cases than HIV negative cases. A study in Kenya demonstrates a 4-fold higher incidence of gonococcal pelvic inflammatory disease in HIV positive prostitutes. These various results highlight the need to integrate STD prevention and control efforts with HIV control programs.