S112 J Med Assoc Thai Vol. 92 Suppl. 1 2009 Correspondence to: Kana K, Armed Forces Research Institute of Medical Sciences, Bangkok 10400, Thailand, Phone: 0-2644-4888, E-mail: k_khunakorn@hotmail.com HIV-1 Incidence Estimates among Young Thai Men Using IgG-Capture BED-Enzyme Immunoassay (BED-CEIA) during 2005-2006 Khunakorn Kana MD*, Sutchana Tabprasit MSc*, Thippawan Chuenchitra PhD*, Narongrid Sirisopana MD, MSc*, Ram Rangsin MD, MPH, Dr PH** * Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand ** Department of Military and Community Medicine Phamongkutklao College of Medicine, Royal Thai Army, Bangkok, Thailand Background: Knowledge about the most recent HIV epidemic among young generation in Thailand is crucial for improving the prevention programs. It is important to distinguish between recent and long-term HIV-1 infections among the sero-surveillance populations to estimate the HIV-1 incidence. Objective: To obtain the HIV-1 incidence estimates in young Thai men from the HIV-1 sero-surveillance among the Royal Thai Army (RTA) conscripts inducted between November 2005 and November 2006. Material and Method: The confirmed HIV-1 positive serum samples obtained from the November 2005, May 2006, and November 2006 rounds of RTA conscripts induction were selected to be included in the study. The recent HIV-1 infections were detected among the confirmed HIV-1 positive serum samples using an HIV-1 BED incidence EIA Kit (Calypte HIV-1 BED Incidence EIA, Calypte Biomedical Corporation, Maryland, USA. The incidence estimates were obtained in each round of the induction using a consensus formula was agreed upon at the US Centers for Disease Controls and Preventions (CDC). Results: Eighty seven thousand one hundred seventy eight RTA conscripts were tested for HIV-1 infection between November 2005 and November 2006. The prevalence of HIV-1 infection was 0.51%, 0.60%, and 0.50% for the period of November 2005, May 2006, and November 2006, respectively. The HIV-1 incidence estimates were 0.14%/year (95% CI, 0.09-0.20), 0.20% year (95% CI, 0.13-0.28), and 0.17%/year (95% CI, 0.10-0.29) in November 2005, May 2006, and November 2006, respectively. Conclusion: We reported the HIV-1 incidence estimates obtained from the IgG-capture BED-enzyme immu- noassay (BED-CEIA) method in the RTA conscripts sero-surveillance population. The incidence estimates were ranging from 0.14% - 0.20%/year between November 2005 and November 2006. The estimates could serve as the recent baseline information for future HIV prevention interventions in Thailand Keywords: HIV-1, Immunoenzyme techniques, Immunoglobulin G, Incidence J Med Assoc Thai 2009; 92 (Suppl 1): S112-6 Full text. e-Journal: http://www.mat.or.th/journal The course of HIV-1 epidemic in Thailand has been decreased dramatically since its peak in the early 1990s (1-3) . Although the successful of the HIV-1 prevention and control program in Thailand has been demonstrated, the occurrance of new infections is still present in general populations. Knowledge about the most recent HIV epidemic in the young generation in Thailand is crucial for improving the prevention programs. In Thailand, several high-risk groups for HIV-1 infection has been evaluated for HIV-1 prevalence under the National HIV-1 Sero-Surveillance Program since 1989. One of the surveillance populations is the military conscripts. The surveillance has been carried out on approximately 60,000 21-year-old military conscripts of the Royal Thai Army (RTA) annually. It is believed to be the nationally representative sample of young Thai men. HIV-1 prevalence data has been