My primary research interests include HIV prevention, health promotion and disease prevention, HIV health service delivery, hepatitis C virus and other co-infections among HIV-positive individuals, the relationships between various micronutrients and HIV disease progression, and continuum of HIV prevention and care. I am also interested in community-based participatory research, particularly evaluation of community-based behavior change interventions. I have studied the factors associated with HIV risk behaviors and have designed, implemented, and evaluated HIV risk behavior change interventions. My research to date has involved international migrants, injecting drug users, HIV-positive individuals, men who have sex with men, female sex workers, traditional healers, policy makers, school students, and other people from the general population. My present research projects include measurement of STI prevalence, sexual risk reduction intervention, and longitudinal assessment of nutrient intake and the association with metabolic markers, oxidative stress, and disease progression among HIV-positive individuals. I am also assessing the causes of death among HIV-positive individuals and HIV service delivery in six Asia Pacific Countries.