A study by the San Francisco Department of Public Health, conducted at the San Francisco County Jail, has found that anonymous HIV screening of jail inmates offers an opportunity to track the epidemic in at-risk groups, particularly those who traditionally under-utilize health care services.
"This type of screening, called sentinel surveillance, offers an early warning system to monitor the extent of HIV infection in a generally low socioeconomic group that doesn't often access screening services," said the study's lead investigator, Willi McFarland, MD, PhD, of the San Francisco Department of Public Health HIV Seroepidemiology Unit and the University of California, San Francisco Center for AIDS Prevention Studies.
Research findings were reported today (July 11) at the XIII International AIDS Conference in Durban, South Africa.
The on-going effort, funded by the Centers for Disease Control and Prevention, involves a close collaboration of the San Francisco health department's AIDS Office, Sexually Transmitted Disease (STD) Prevention and Control Services, and Forensic AIDS program.
Researchers conduct the HIV testing through an STD services screening program established by the health department three years ago at the county jail. It offers voluntary screening for gonorrhea, syphilis, and chlamydia within hours of arrest to male inmates aged 18-35 and females 18-45. Most prisoners offered the services have chosen to participate in the program, and it has detected a higher number of STDs than are typically picked up in screening programs that are available to populations outside the jail setting, said McFarland. "We saw in this successful STD screening program an opportunity to conduct a completely blinded HIV surveillance survey in high-risk groups brought to the jail," said McFarland.
The study, which began in June 1999, tested for HIV in residual blood samples drawn for syphilis testing. Researchers did not track the patients by name, but were able to follow demographic characteristics and behaviors that put individuals at risk for HIV, such as intravenous (IV) drug use, or men having sex with men.
At the Durban meeting, results were reported for the period June 1999 to February 2000.
Researchers found HIV in about 2 percent of 3,019 inmates who underwent screening--a rate about 5 times greater than would be expected in the general heterosexual population of San Francisco. The highest levels of HIV infection (19 percent) were found in men who had sex with men and were also IV drug users. Men who had sex with men and did not inject drugs had a 16 percent level of infection. HIV-positive inmates of either sex were also more likely to report injection drug use, having sex with a man, and having sex with an HIV-infected partner.
The researchers were also able to determine which groups appeared to have been more recently infected with the virus, because the study used a new HIV diagnostic test that can determine whether infection has occurred within the last six months. Most recent infections found in the jail were associated with drug use.
Rates of others STDs in the study population were 2 percent for gonorrhea, 7 percent for chlamydia, and 0.1 percent for syphilis. Although this HIV surveillance screening program is conducted on an anonymous basis and inmates do not find out their test results, confidential HIV screening and treatment referral are available on request for inmates who want to know their HIV status, said McFarland.
Study co-investigators included Andrea Kim, MPH, of the SF Department of Public Health HIV Seroepidemiology Unit, who presented the findings at the Durban meeting; Tim Kellogg, MA, also of the HIV Seroepidemiology Unit; Charlotte Kent, MPH, Robert Kohn, MPH, and Ameera Snell, BA, of the SF Department of Public Health STD Prevention and Control program; Joe Goldenson, MD, of the SF Department of Public Health, Forensic Services; and Keith Bordelon, MPH, and Keith Sabin, PhD, MPH, of the US Centers for Disease Control and Prevention. Jeffrey Klausner, MD, MPH, director of STD Control for the SF Department of Public Health, is the co-principal investigator.