CAN DIFFICULT-TO-REUSE SYRINGES REDUCE THE SPREAD OF HIV AMONG INJECTION-DRUG USERS

Sharing of syringes by injection drug users is a principal means by wh ich the human immunodeficiency virus (HIV) is spread. Some have sugges ted that distributing syringes that are difficult to reuse (DTR) would slow the spread of HIV. We developed a simple mathematical model that describes how changes in the numbers of DTR syringes or regular syrin ges consumed over the course of a fixed number of injections affects t he proportion of injections that are potentially infectious and, thus, the transmission of HIV. It suggests that increasing consumption of e ither type of syringe will reduce the proportion of potentially infect ious injections, but that, per syringe added, the reduction is always greater if a regular rather than a DTR syringe is added. Similarly, in troducing a certain number of DTR syringes and simultaneously reducing the consumption of regular syringes by the same number will increase, not decrease, the proportion of infectious injections. DTR syringes a re more expensive than regular syringes, so there is little justificat ion for substituting them for regular syringes.