MODELING THE EXPANSION OF THE HIV EPIDEMIC IN ST. PETERSBURG, RF

The high prevalence of HIV infection and substantial rates of unprotected sexual intercourse reported among injection drug users in St. Petersburg has led to speculation that sexual transmission of HIV from IDUs to their non-injecting heterosexual partners (PIDUs) may generate a self-sustaining, heterosexual epidemic. We constructed a mathematical model that incorporated behavioral data from a survey of St. Petersburg IDUs and their sexual partners into an epidemic model that combines a network model of sexual partnerships of IDUs and non-IDUs to represent sexual transmission of HIV and a deterministic model for parenteral transmission among IDUs. We compared the model to surveillance data obtained from testing conducted throughout St. Petersburg and from targeted testing of IDUs. The model closely follows both forms of surveillance. The model outputs reveal a constant HIV prevalence of approximately 50% among IDUs, increasing prevalence among PIDUs and the general population reaching 14% and 2%, respectively, by 2025. These high HIV prevalences outside of IDUs occur because parenteral transmission drives the epidemic and the PIDU bridge population plays a crucial role transferring infection into the general population. This implies that sexual transmission could sustain a non-IDU HIV epidemic but only if parenteral trans mission remains unchecked. Thus, the key to epidemic control is reducing transmission among IDUs by a combination of prevention programs and antiretroviral treatment to reduce viral load.

Распространенность ВИЧ-инфекции, потребители инъекционных наркотиков, моделирование эпидемии, передача парентеральным и половым путем, контроль за эпидемией, HIV Prevalence, Injection Drug Users, Epidemic Modeling, Parenteral and Sexual Transmission, Epidemic Control

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