Use of sentinel surveillance and geographic information systems to monitor trends in HIV prevalence, incidence, and related risk behavior among women undergoing syphilis screening in a jail setting

Abstract

Innovative methods are needed to systematically track the HIV epidemic and appropriately target prevention and care programs in vulnerable populations of women. We conducted sentinel surveillance among women entering the jail system of San Francisco from 1999 to 2001 to track trends in HIV incidence, HIV prevalence, and related risk behavior. Using geographic information software (GIS), we triangulated findings to examine the spatial distribution of risk and disease. A total of 1,577 female arrestees voluntarily screened for sexually transmitted diseases at intake were included. HIV incidence, estimated using the serologic testing algorithm for recent HIV seroconversion (STARHS), was 0.4% per year (95% confidence interval [95%CI]=0.1-2.1). HIV prevalence was 1.8% (95%CI=1.1-2.4). HIV infection was independently associated with age 30 to 39 years compared to all other ages, African-American race/ethnicity vs. non-African-American, and recent injection drug use. Maps showed that the communities in which arrested women reside are also those with the highest concentrations of newly detected female HIV cases, AIDS cases, and clients of substance use programs. The combined strategy of using sentinel surveillance in the jail setting and GIS to map the spatial distribution of disease provides a useful tool to identify patterns of risk in hard-to-reach, vulnerable populations of women.

FIGURE 1.

Trends in HIV prevalence and sexually transmitted infections, women upon intake in San Francisco County Jail, 1999–2001. The asterisk represents the 95% CI.

FIGURE 2.

Spatial distribution of female arrestees identified at San Francisco County Jail, 1999–2001. a Median household income, 2000; b reported AIDS cases in women, 2002; c women arrested, 1999–2001; d HIV-positive women arrested, 1999–2001.

FIGURE 3.

Concentration of female clients for injection drug use services (e.g., detoxification, methadone maintenance) and women-only syringe exchange sites. The kernel density estimation method in ArcGIS software was applied to display the data on this map.