Heroin Type, Injecting Behavior, and HIV Transmission. A Simulation Model of HIV Incidence and Prevalence

Abstract

Background and Aims. Using mathematical modeling to illustrate and predict how different heroin source-forms: "black tar" (BTH) and powder heroin (PH) can affect HIV transmission in the context of contrasting injecting practices. By quantifying HIV risk by these two heroin source-types we show how each affects the incidence and prevalence of HIV over time. From 1997 to 2010 PH reaching the United States was manufactured overwhelmingly by Colombian suppliers and distributed in the eastern states of the United States. Recently Mexican cartels that supply the western U.S. states have started to produce PH too, replacing Colombian distribution to the east. This raises the possibility that BTH in the western U.S. may be replaced by PH in the future.Design. We used an agent-based model to evaluate the impact of use of different heroin formulations in high-and low-risk injecting drug user populations who use different types of syringes (high vs. low dead space) and injecting practices. We obtained model parameters from peer-reviewed publications and ethnographic research.Results. Heating of BTH, additional syringe rinsing, and subcutaneous injection can substantially decrease the risk of HIV transmission. Simulation analysis shows that HIV transmission risk may be strongly affected by the type of heroin used. We reproduced historic differences in HIV prevalence and incidence. The protective effect of BTH is much stronger in high-risk compared with low-risk populations. Simulation of future outbreaks show that when PH replaces BTH we expect a long-term overall increase in HIV prevalence. In a population of injectors with mixed low-and high-risk clusters we find that local HIV outbreaks can occur even when the overall prevalence and incidence are low. The results are dependent on evidencesupported assumptions. Conclusions.The results support harm-reduction measures focused on a reduction in syringe sharing and promoting protective measures of syringe rinsing and drug solution heating.

Navigating environmental constraints to injection preparation: the use of saliva and other alternatives to sterile water among unstably housed PWID in London

“…Ciccarone and Bourgois [53] present a hypothesis that cold water heroin solutions may have fostered HIV transmission in the early phases of the epidemic in the USA. More recently, a model of HIV transmission examining heroin source-type (including cold water prepared solutions) supports this prior hypothesis [54]. Gaskin et al [55] present one of the few studies with a HCV transmission remit to detail water source.…”