Incidence of HIV Among Male-to-Female Transgendered Persons in San Francisco

Several recent studies have reported high levels of risk behavior and prevalence of HIV infection among male-to-female (MtF) transgendered persons. A recent community-based survey in San Francisco found that 35% of MtF transgendered persons were HIV-positive. In addition, 63% of African-American MtF transgendered persons were HIV-positive -- one of the highest estimates of HIV prevalence of any population at risk in San Francisco. The objective of this study was to estimate HIV incidence among MtF transgendered persons who repeatedly tested for HIV antibodies at public San Francisco counseling and testing sites between July 1997 and June 2000.

Although a high HIV prevalence indicates a high burden of disease, prevalence measures cannot assess frequency nor predict new HIV infections. Data on HIV incidence are needed to monitor current trends in HIV transmission, target primary prevention efforts, and measure the impact of prevention interventions. Unfortunately, HIV incidence estimates are rare for transgendered populations because few longitudinal cohort studies have included sufficient numbers. An exception is a recent cohort study among MtF transgendered persons in Los Angeles that observed an HIV incidence of 3.4 per 100 person-years (py). However, because the estimate was based on only four seroconversions, the authors were unable to examine predictors of seroconversion.

In July 1997, the San Francisco Department of Public Health expanded the gender categories on HIV testing requisition forms to include transgendered persons. Among 79,148 confidential and anonymous HIV tests performed in San Francisco between July 1997 and June 2000, 238 (0.3%) of those tested self-identified as MtF transgendered persons. Researchers also examined the written "specify other gender" field on the counseling and testing form to identify other variations of MtF transgendered persons, most notably "male pre-op" and "male transsexual." HIV incidence was estimated following the methods of Kitayaporn et al. and used by other researchers for similar databases. A seroconverter was defined as a person repeatedly tested whose last self-reported test result was negative for HIV and whose current test result was positive.

Overall prevalence of HIV was 15.5%, with highest prevalence among African-Americans and those with unknown race/ethnicity (both 33.3%). The HIV incidence among MtF transgendered persons was 7.8 per 100 person-years based on 13 seroconversions among 155 eligible repeat testers providing 167.7 person-years of observation. The sample of MtF transgendered HIV testers was racially mixed with over two-thirds identifying as African-American, Latino, or Asian/Pacific Islander. The median age was 33 years (range 19-66). The most frequently reported sexual orientations were heterosexual and bisexual (29% and 27.7% respectively). HIV prevalence was highest among MtF transgendered persons identifying as bisexual (25.8%). Over three-quarters of the sample reported having a male sexual partner in the past 12 months.

Predictors of HIV seroconversion included demographic characteristics and sexual and drug use behaviors as reported by those tested. Eight variables were associated with higher HIV incidence (African-American race, Latino ethnicity, age between 36-40 years, sex with an injection drug user [IDU] in the past year, unprotected receptive anal sex in the past year, unprotected insertive anal sex in the past year, injection drug use in the past year, exchanged sex for money or drugs in the past year, and methamphetamine [speed] use in the past year).

Data from this research indicates that HIV is currently spreading at an extremely high rate among MtF transgendered persons in San Francisco. The HIV incidence estimate of 7.8 per 100 person-years is the highest recently reported for any at-risk population in San Francisco and is comparable with rates observed among gay men at the height of the epidemic in the 1980s. Levels of risk behavior observed in several recent studies of MtF transgendered persons corroborate the interpretation of high HIV incidence. The data also suggest that African-American MtF transgendered persons are experiencing the highest rate of new infections. This finding is consistent with other studies of transgenders that found high HIV prevalence among African Americans.

The HIV counseling and testing data cannot fully explain how MtF transgendered persons are becoming infected with HIV. However, unprotected receptive anal sex is the most likely mode of HIV acquisition because it was the only reported behavior significantly associated with HIV seroconversion in the research analysis. Further, it is likely that the source population was men who have sex with men (MSM), because HIV infection among heterosexual men in San Francisco is rare. It is possible that a sub-population of MSM have frequent sexual contact with MtF transgendered persons and that sexual networks connecting these two populations may represent current, active chains of HIV transmission. To better understand HIV risk, future studies will need to focus on understanding the sexual networks and partner groups of MtF transgendered persons particularly among African-Americans, including ascertaining the HIV serostatus and specific sexual behaviors. Other research should also focus on determining barriers to early intervention among HIV-positive MtF transgendered persons.

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