220   How Common Is Secondary Transmission of HIV in the U.S.?

R. M. Klevens*, P. L. Fleming, J. J. Neal, and J. Li.
CDC, Atlanta, GA.

Background:The number and proportion of persons infected heterosexually with HIV, and whose partners had no primary HIV risk factor, have increased. We evaluated the extent of secondary heterosexual transmission of HIV in the U.S., characterized persons at highest risk, and measured the frequency with which persons with heterosexually acquired AIDS knew their partner's risk behaviors.

Methods:We interviewed a random sample of adults with AIDS, acquired heterosexually or reported without risk, in six sites (Alabama, California, Florida, New Jersey, New York City, and Texas). All had AIDS diagnosed between 1992 and 1995. Primary heterosexual transmission was contact with a partner infected through male-to- male sex, injection drug use, or receipt of contaminated blood or tissue. Secondary transmission was contact with an HIV-positive partner not known to have an above-listed risk.

Results:Of the 598 persons interviewed, 581 (97%) reported at least 1 heterosexual partner. Among men 236/ 293 (81%) and among women 224/288 (78%) reported a partner with a primary risk. Persons reporting secondary transmission were significantly more likely to be black and never married. Persons reporting secondary transmission were more frequently women (53%), had less than a high school education (48%), and had a history of drug use (52%). Men reporting secondary transmission of HIV had a mean of 22 heterosexual partners; women had a mean of 16. At least 24% of women did not know if their partners had risk factors for HIV. Applying findings from this study to national surveillance data, <4.8% of adult cases and <20.8% of heterosexual cases reported in 1999 would have been acquired through secondary heterosexual transmission.

Conclusions:Secondary heterosexual transmission of HIV was not widespread in these U.S. sites; multiple sexual contacts were frequent among persons who did not recognize partner risk. Efforts to address high-risk heterosexual behavior include reducing the number of sex partners, regardless of their perceived risk, and increasing condom usage with partners with known risk behaviors or unknown sero-status.