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Epidemiology and Transmission Updates from the 8th Annual Retrovirus Conference

March 23, 2001

The 8th Annual Conference on Retroviruses and Opportunistic Infections (Retrovirus) met in Chicago from February 4-8, 2001. Many of the lectures and symposia are available for viewing on the conference's website ( Posters and abstracts, referenced and numbered in parentheses in this report, are also available on the website.

"Secondary" Prevention Aimed at HIV-Positive People

A new concept that is gaining momentum nationally with the Centers for Disease Control and Prevention (CDC) is the idea of developing HIV/AIDS prevention programs aimed at HIV-positive, rather than HIV-negative, individuals. A number of abstracts and discussions dealing with this topic, often called "secondary prevention," were presented at Retrovirus. In particular, one symposium explained a new CDC program called the Serostatus Approach to Fighting the [HIV] Epidemic (SAFE). This initiative promotes interventions for HIV-positive people, to prevent transmission to sexual partners. SAFE focuses on (1) testing and diagnosing all HIV-positive individuals, (2) linking people to appropriate, high-quality care and prevention services, (3) helping individuals adhere to treatment regimens, and (4) supporting individuals in reducing HIV transmission risk behaviors.

Early HIV Diagnosis Adds to Prevention Efforts

Evidence to support the idea of secondary prevention came from many abstracts. One of these dealt with the level of high-risk behaviors among people recently infected or newly diagnosed with HIV (Abstract 216). This study involved HIV-positive men and evaluated the factors associated with continued high-risk behavior. One hundred and sixteen individuals diagnosed with HIV, many during acute or primary infection were recruited within three months of their diagnosis for an interview study with two-year follow-up. Sixty-two of the individuals have completed both the interviewer-administered questionnaire given at baseline and the one given at 12 months post-diagnosis. Researchers looked at changes in HIV transmission behaviors and any associations between recreational drug use and high-risk behavior.

Many participants reported reducing recreational drug use following HIV diagnosis (84% at baseline and 58% at 12-month follow up). Most also reported a reduction in the number of sexual partners. At baseline, 74% of men who have sex with men (MSM) had more than five partners in the previous six months, while only 50% reported that many partners at 12 months. For men who have sex with women, the percentage reporting more than five partners in the previous six months dropped from 22% at baseline to 0% at 12 months. Reductions in sex in bathhouses, sex clubs and other public sex environments among MSM also dropped (63% at baseline and 44% at 12 months).

Of the small number of participants who reported continued drug use after HIV diagnosis, there were increases in the percentage who reported that marijuana, speed, or cocaine powder was their most frequently used drug (marijuana 10% to 67%, speed 10% to 30%, cocaine 4% to 16%). In MSM, marijuana use was associated with reports of sex with more than five partners in the previous six months.

The observed reductions in risk behavior among the majority of participants in the study, even in the absence of any targeted HIV prevention messages, emphasizes the importance of early HIV diagnosis as a means of preventing further transmission. The persistence of high-risk behavior in a significant proportion of respondents, however, points to the need for reinforcement of prevention messages among HIV-positive individuals. Prevention efforts could also be effective by targeting recreational drug use among MSM, which was associated with more risk behaviors.

HIV Rates and Risk Behavior Continue to Increase Among Young MSM

Several presentations and posters at Retrovirus highlighted recent trends in HIV epidemiology. One study, in particular, received a great deal of attention from the popular press. The study, conducted by the CDC from 1998 to 2000 in Baltimore, Dallas, Los Angeles, Miami, New York, and Seattle, found that the rates of HIV infection in men who have sex with men (MSM) aged 20 to 30 were alarmingly high (Abstract 211). In this ongoing study called the Young Men's Survey (YMS), epidemiologists surveyed more than 2,400 men at bars and other places frequented by young MSM and conducted extensive interviews. The prevalence of HIV among MSM ranged from a low of 5% in Seattle to 18% in Dallas, and there was a high level of "risky" sexual behavior in all six cities.

According to the most recent findings from YMS, 12% of MSM who were between 23 and 29 years old were HIV-positive. The incidence increased with age within this group, from 10% among 23- to 25-year-olds to 14% among 26- to 29-year-olds. The study found that among the men surveyed, 30% of African-Americans, 15% of Hispanics, 7% of non-Hispanic whites and 3% of Asian-Americans are infected with the virus.

Forty-six percent of participants said they had unprotected anal intercourse in the preceding six months. Of the 293 HIV-positive men in the study, only 29% knew they were HIV-positive before being tested as part of the study. This information has alarmed the prevention community and the CDC suspects that a substantial proportion of current HIV transmission is from people who do not know that they are infected. Although there is no direct evidence of rising HIV infections among MSM in most areas, this and earlier studies raise suspicions that such an increase may be occurring.

Evidence of Sexual Transmission of Hepatitis C Virus in a Study of MSM

Another interesting transmission issue is whether or not there is sexual transmission of the hepatitis C virus (HCV), especially among MSM. Most transmission of HCV is thought to be through blood-to-blood contact such as needle sharing during drug use. The objective of this study was to determine HCV prevalence and identify risk factors for HCV infection (Abstract 561). This study screened for evidence of HCV infection (HCV antibodies) in blood samples obtained from sexually active MSM in Vancouver B.C. between 1982 and 1998.

A total of 39 of the 662 participants (5.9%) were identified as HCV-positive. HCV prevalence was significantly higher among HIV-positive men (31 of 352) compared to HIV-negative men (8 of 310). Seventy-four percent of HCV-positive men had more than 20 partners in the previous year, compared to 48% of HCV-negative men, and 80% of HCV-positive men had more than 100 partners in their lifetime, compared to 62% of HCV-negative men.

Not surprisingly, a history of injection drug use was a significant risk factor for HCV infection. However, 49% (19 of 39) of HCV-positive men in this study reported never using injected drugs. When these non-injection drug using (IDU) HCV-positive men were compared to other non-IDU men, specific sexual practices were identified as significant risk factors for becoming HCV-positive. These were oral-anal contact and insertive fisting.

Look for more STEP coverage from the 8th Annual Conference on Retroviruses and Opportunistic Infections in the next issue of the STEP Perspective. To subscribe, send your address to

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This article was provided by Seattle Treatment Education Project. It is a part of the publication STEP Ezine.