HIV Transmission Rates in Thailand

HIV Transmission Rates in Thailand:

Analysis of HIV transmission rates has provided insight into the impacts of HIV-related prevention programming and policies in the United States by providing timely information beyond incidence or prevalence alone. The purpose of this analysis is to use transmission rates to assess past prevention efforts and explore trends of the epidemic in subpopulations within Thailand. Asian Epidemic Model HIV incidence and prevalence were used to calculate transmission rates over time nationally and among high-risk populations. A national HIV program implemented in Thailand in the 1990s that targeted sex workers and the general population was correlated with a decrease in new cases despite high prevalence. The turning point of the epidemic was in 1991 when the national transmission rate was 32%. By the late 1990s, the rate dropped to less than 4%. All subpopulations experienced a rate decline; however, sex workers still experienced higher transmission rates. The declining trend in HIV transmission rates despite ever-growing prevalence indicates prevention success correlated with the national HIV program. Data from subgroup analyses provide stronger evidence of prevention success than incidence alone, as this measure demonstrates the effect of efforts and accounts for the burden of disease in the population.

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Editors’ note: This paper defines the HIV transmission rate as the new cases of HIV divided by the existing number of persons living with HIV for a specified time. It provides a measure that considers the spread of HIV by accounting for the number of people capable of transmitting HIV. How accurate the transmission rate calculated in this manner will be clearly depends on how good are the HIV incidence and prevalence estimates. Nevertheless, Thailand has clearly met the Millennium Development Goal 6 ‘to halt and reverse the spread of HIV by 2015’ through sustained reductions in HIV incidence. This resulted from the swift action that provoked dramatic changes in HIV incidence from a peak in 1991 and concerted prevention programming thereafter. These included mobilisation of non-governmental organisations, the 100% condom use campaign that went national in 1992, blood screening programmes, and active surveillance. It is unclear how accurate transmission rates calculated this way are for key populations such as men who have sex with men, people who inject drugs, and couples in which one person has HIV infection, but the need to engage these people in the design of effective tailored prevention programming and better surveillance is clear.