Important note: Information in this article was accurate in January 2002. The state of the art may have changed since the publication date.
Though bioterrorism was clearly the issue of the day at the 39th Annual Meeting of the IDSA, new observations regarding the important epidemiologic interactions between sexually transmitted diseases (STDs) and HIV were brought to the fore at this conference as well.
Genital Herpes and HIV
In the Enders lecture, Dr. L. Corey of the University of Washington presented more data indicating a large, and perhaps even growing role, for HSV-2 in driving sexual transmission of HIV [Abstract P88]. In a meta-analysis that included 9 prospective or nested case-control studies, the relative odds of prior HSV-2 infection and subsequent HIV acquisition was 2.1 (95% CI 1.3-3.2). He also cited new, recently published data from the Rakai study [HHR 10(5) 8/98; HHR 11(1) 1/2000] examining risks for HIV transmission among 174 couples discordant for HIV [Gray RH. Lancet 2001 Apr 14;357(9263):1149-53]. Reactive HSV-2 serology conferred a 2-4 fold greater risk of HIV transmission within every stratum of HIV viral load. There was no increased risk of transmission if a symptomatic genital ulcer was reported, indicating that subclinical HSV-2 microulcerations and shedding confer significant added risk, even equal to the risk conferred by clinically apparent ulcers. An increasing
proportion of genital ulcerations from clinical cohorts in sub-Saharan Africa over the past 2 decades appears to be due to HSV-2. Suppression of subclinical genital HSV-2 shedding with antivirals may help to prevent HIV transmission in Africa.
Resurgent Sexually Transmitted Diseases in the AIDS Era
In a symposium covering biologic, epidemiologic, and behavioral interaction of STDs and HIV, Dr. Myron Cohen of UNC summarized what is known to date regarding biologic determinants of HIV infectiousness and HIV susceptibility, as well as biomedical interventions that might prove effective in preventing HIV transmission while we await the arrival of an HIV vaccine [Abstract S79]. In what he called the "biologic view of sub-Saharan Africa," Cohen listed the following factors that facilitate the spread of HIV as tipping the balance against control of the epidemic: Higher blood:semen viral HIV concentrations; clade C predominance, with a fixed non-syncytium-inducing (NSI) phenotype, which may be more efficiently sexually transmitted; and the high population prevalence of STDs. Cohen pointed to the following factors that increase biologic susceptibility to HIV acquisition: High prevalence of STDs and bacterial vaginosis; low prevalence of CCR5 gene deletions; and the low rate
of male circumcision (keratinized epithelial surfaces created by male circumcision in infancy are probably protective). There may also be higher rates than previously recognized of iatrogenic or occupational exposures in Africa through percutaneous instrumentation (needlesticks, etc).
In a presentation entitled, "Sex, Drugs, and Perestroika," Dr. Adrian Renton of the London Imperial College of Medicine summarized alarming epidemiologic trends in syphilis and HIV that have occurred in the Russian Federation [Abstract S80]. Disease control strategies in the former Soviet Union were entirely publicly-funded and focused on government-supported compulsory hospitalization to prevent syphilis spread, along with strictly enforced contact tracing. In the current Russian Federation most STD services are provided on a fee-for-service basis with a more relaxed approach to contact notification and preventative treatment. A surge in injection drug use (IDU) and commercial sex has occurred simultaneously with this shift in infrastructure and delivery of STD services. The result has been an explosion in syphilis and HIV transmission. Estimated primary/secondary syphilis rates have exceeded 250 cases per 100,000, with the peak age of occurrence in the late teenage
years. Current strategies to prevent HIV transmission are to focus on STD control among IDUs and aggressively promote condom use among young people.
Dr. Connie Celum of the University of Washington summarized recent data on STDs among men who have sex with men (MSM) [Abstract S81]. Surveillance data from several urban centers in the U.S. and Europe has described multiple syphilis outbreaks among MSM in the last half of the 1990’s. To study determinants of sexual risk-taking and STDs among MSM in Seattle, approximately 1000 MSM (30% were HIV-seropositive) were recruited from STD clinics and HIV primary care clinics. Overall, HIV-infected MSM were not sexually safer, with 31% reporting meeting partners anonymously at bath houses or sex clubs, compared to 22% of HIV-seronegative men reporting this behavior. The prevalence of gonorrhea or chlamydia (isolated from oral, anal, or rectal sites) was 10% among HIV-infected MSM and 13% among HIV-uninfected MSM, with most infections being asymptomatic. These findings have significant implications for HIV clinical providers: Discussion of sexual risk behaviors, especially specific
types of sexual practices and the use of anonymous venues to meet partners, along with periodic screening for bacterial STDs should be a consistent standard in clinical practice.
Dr. Steven Morin presented recent epidemiologic trends in San Francisco that demonstrate a new rise in HIV incidence over each successive quarter of 2000 [Abstract S82]. To design effective prevention interventions to address this trend, focus groups comprised of MSM in San Francisco were assembled. The questions presented to the focus groups were as follows:
The groups identified the following as factors contributing to HIV transmission, but that had not changed significantly over the past several years:
The following were phenomena that the groups identified as having changed in the past several years and may be contributing to the recent increase in HIV incidence:
The focus groups endorsed health promotion advertisements that focused on friends talking to friends about safer sex, that provided facts on the rising rates of HIV in San Francisco, that explained that HIV still had very negative health consequences, and that promoted safer sex as "still the norm."
As we move into the fourth decade of the HIV/AIDS epidemic without a prophylactic vaccine, improved STD control is as important as ever in preventing the spread of HIV. New data indicate that clinical trials of genital herpes suppression, along with a more aggressive focus on STD screening and prevention services in HIV clinical practice, should now be high priority items on the HIV prevention agenda.
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