HIV prevalence declined among high-risk group

Serosurveillance at STD clinics has value

Investigators analyzing data obtained from at-risk populations in the Western United States found a decline in HIV infection between 1989 and 1999, a new study shows.

"We saw declines over time in all of the behavioral lists, including injection-drug users (IDUs), heterosexuals, and men who have sex with men (MSM)," says Nina Harawa, MPH, PHD, an epidemiologist at the Los Angeles County Department of Health Services — Public Health in Los Angeles.

The study used data from leftover blood samples that were obtained for routine syphilis testing from 256,819 patient visits to sexually transmitted disease (STD) clinics in Denver, Los Angeles, San Francisco, and Seattle.1

Among men who have sex with men (MSM), HIV prevalence, from the 1989-1990 period and compared to 1998-1999, declined at least 50% in all of the counties included in the study, and among women, HIV prevalence declined at least 30% in all but one county.1

There were HIV-prevalence declines among IDUs and minorities, but the declines among African Americans were the least dramatic, the study showed.

"What we see in Los Angeles, for example, is that African American women, in particular, continue to become a larger and larger proportion of new cases," Harawa explains. "But it’s not that their absolute numbers of new infections are increasing."

However, the declines observed in HIV prevalence among African American women was less pronounced than the declines observed among heterosexual men, she adds.

Investigators linked HIV status to basic information collected during the STD clinic visit, including sexual behavior information, such as the gender of the sexual partner, and how the respondent identified his or her sexual orientation.

Study’s main findings

Some of the study’s main findings were as follows:

  • HIV prevalences among MSM were 15 to 60 times that of heterosexual men and women.1
  • Of all HIV-positive tests, MSM comprised 73%.1
  • The 30 to 39 year age group was the least likely to be infected.1
  • The Western cities’ HIV infection levels among MSM in 1998/99 were lower than the range observed in the Northeast and Southern regions of the United States in 1997.1

Since the study was completed and funding from the Centers for Disease Control and Prevention (CDC) ended, the serosurveillance method mostly has ended, Harawa says.

"It was done as a national effort," she notes. "Now the CDC has been putting more effort into other areas like HIV and AIDS reporting and developing systems to test people who have recently reported HIV cases to identify whether they are recent infections."

However, the serosurveillance effort had some positive aspects that may be lost in the cities that no longer test blood for HIV after it already has been collected for syphilis testing.

For example, Seattle, which has continued the serosurveillance at its STD clinics using local funding, has found that there is a resurgence of new infections among MSM, Harawa says.

"They found in the later years, 2000 through 2001, a reversal in trends," she explains. "Where we saw a decline among MSM of HIV infection, they started to see it going up."

If all of the cities had continued their HIV serosurveillance efforts, it’s possible the trend might have been identified across the Western region, Harawa says. If HIV testing sites and STD clinics only identify HIV infection among the people who volunteer for HIV testing, they likely will miss these sorts of trends among high risk populations, she notes.

"We have general populations of people with HIV, and in the absence of sentinel surveillance, we’re missing out on information from high-risk people who may not accept testing. An STD clinic is a particularly high-risk setting, and there’s the potential that other STD epidemics could portend a rise in HIV," Harawa points out.

Syphilis is a good example of this potential because there have been a number of syphilis outbreaks in recent years, Harawa adds.

"The benefit of serosurveillance in these cities is that most people who are tested at public STD clinics are routinely tested for syphilis because it’s a blood test and leftover serum could be used for HIV testing," she says.

"It lets us get a good snapshot of the STD clinic population and who has refused testing," adds Harawa. "This way we have a group of high-risk people who are there not because of HIV but because of symptoms of another disease."

For all of these reasons, HIV surveillance in STD clinics offers a unique perspective that is worth reinstating, she says.

The study also highlights the need for increased HIV prevention counseling in STD clinics, as well as more sensitive efforts at identifying a person’s risk behaviors.

"The concern is that some STD clinics or private providers may not ask questions in a way that is sensitive enough to learn about behavior," Harawa adds. "It’s their behavior that’s important and it doesn’t matter whether they call it straight’ or gay.’"


1. Harawa NT, Douglas J, McFarland W, et al. Trends in HIV prevalence among public sexually transmitted disease clinic attendees in the Western region of the United States (1989-1999). J AIDS 2004; 37(1):1,206-1,215.