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Higher Viral Loads and Other Risk Factors Associated With HIV-1 Seroconversion During a Period of High Incidence Among Injection Drug Users in Bangkok

Hu Dale J.; Subbarao, Shambavi; Vanichseni, Suphak; Mock, Philip A.; van Griensven, Frits; Nelson, Robert; Nguyen, Lily; Kitayaporn, Dwip; Young, Nancy L.; Des Jarlais, Don; Byers, Robert Jr.; Choopanya, Kachit; Mastro, Timothy D.
JAIDS Journal of Acquired Immune Deficiency Syndromes: June 1st, 2002
doi: 10.1097/01.QAI.0000014770.35851.44
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We analyzed data from a prospective cohort study of injection drug users (IDUs) attending methadone treatment clinics in Bangkok, Thailand, during 1995-1998 to characterize factors associated with a period of high incidence (PHI) from July 1996 through January 1997 compared with periods of lower incidence. Sociobehavioral characteristics were similar for all participants during and outside the PHI except for the following: there was more reported drug injection while IDUs were incarcerated during the PHI (odds ratio, 1.67; p = .02) and significantly higher proportions of persons reported heroin injection (91% vs. 75%, respectively; p = .02) and higher frequencies of daily injection and sharing of injection equipment (40% vs. 25%, respectively; p = .05) during the PHI than outside the PHI. Through most of the first year after seroconversion, plasma HIV-1 loads were significantly higher in persons who seroconverted during the PHI than in those who seroconverted outside the PHI. Higher viral loads may potentially contribute to faster disease progression and increased infectiousness or transmissibility to subsequent contacts. Our findings suggest that prevention efforts to reduce the effective size and turnover within IDU sharing networks may have a significant impact on the epidemic by disrupting the rapid transmission of HIV-1 from recently infected, highly infectious individuals.

Address correspondence to Dale J. Hu, HIV Vaccine Section Epidemiology Branch/DHAP, Centers for Disease Control and Prevention, Mailstop E-45, Atlanta, GA 30333, U.S.A.; e-mail:

Address reprint requests to Thailand MOPH-U.S. CDC Collaboration DMS 6 Building, Ministry of Public Health, Tivanon Road, Nonthaburi 11000, Thailand.

Manuscript received October 18, 2001; accepted February 20, 2002.

© 2002 Lippincott Williams & Wilkins, Inc.