%0 Journal Article
%T What Drives the US and Peruvian HIV Epidemics in Men Who Have Sex with Men (MSM)?
%A Steven M. Goodreau
%A Nicole B. Carnegie
%A Eric Vittinghoff
%A Javier R. Lama
%A Jorge Sanchez
%A Beatriz Grinsztejn
%A Beryl A. Koblin
%A Kenneth H. Mayer
%A Susan P. Buchbinder
%J PLOS ONE
%D 2012
%I Public Library of Science (PLoS)
%R 10.1371/journal.pone.0050522
%X In this work, we estimate the proportions of transmissions occurring in main vs. casual partnerships, and by the sexual role, infection stage, and testing and treatment history of the infected partner, for men who have sex with men (MSM) in the US and Peru. We use dynamic, stochastic models based in exponential random graph models (ERGMs), obtaining inputs from multiple large-scale MSM surveys. Parallel main partnership and casual sexual networks are simulated. Each man is characterized by age, race, circumcision status, sexual role behavior, and propensity for unprotected anal intercourse (UAI); his history is modeled from entry into the adult population, with potential transitions including HIV infection, detection, treatment, AIDS diagnosis, and death. We implemented two model variants differing in assumptions about acute infectiousness, and assessed sensitivity to other key inputs. Our two models suggested that only 4每5% (Model 1) or 22每29% (Model 2) of HIV transmission results from contacts with acute-stage partners; the plurality (80每81% and 49%, respectively) stem from chronic-stage partners and the remainder (14每16% and 27每35%, respectively) from AIDS-stage partners. Similar proportions of infections stem from partners whose infection is undiagnosed (24每31%), diagnosed but untreated (36每46%), and currently being treated (30每36%). Roughly one-third of infections (32每39%) occur within main partnerships. Results by country were qualitatively similar, despite key behavioral differences; one exception was that transmission from the receptive to insertive partner appears more important in Peru (34%) than the US (21%). The broad balance in transmission contexts suggests that education about risk, careful assessment, pre-exposure prophylaxis, more frequent testing, earlier treatment, and risk-reduction, disclosure, and adherence counseling may all contribute substantially to reducing the HIV incidence among MSM in the US and Peru.
%U http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0050522