Syringe type and drug injector risk for HIV infection: a case study in Texas

Studies of accidental needlestick exposure to blood containing human immunodeficiency virus (HIV) have shown that the volume of blood in an exposure is a strong predictor of subsequent infection. Illicit drug injectors, a group at elevated risk for HIV transmission, use syringes manufactured in two styles, one of which (the integral cannula type) retains substantially less blood after intravenous use than the other (the detachable needle type). In this report, we examine some of the factors associated with use of syringes with detachable needles among drug injectors in San Antonio, Texas using data from epidemiological surveys, ethnographic studies, and historical observations. We compare personal history of syringe type use with HIV serostatus in a sample of 501 active drug injectors interviewed and screened for HIV in 1997–1998. Ninety-nine percent of these respondents reported that they currently used only integral cannula syringes, but 13% had used a syringe with a detachable needle within the past 2 years, and 37% had used one in their lifetime. Only 9% had ever used one greater-or-equal, slanted20 times in a year. Hispanic (Mexican American) respondents were significantly less likely than other ethnic groups to have ever used a detachable needle syringe. HIV seroprevalence was <1% among heterosexual injectors who had never used a detachable needle syringe compared to 4% among those who had used one (p<0.05).