The number of HIV infections and AIDS cases in Thailand are not based
on direct count, but rather on estimates derived from various data sources.
Given the number of qualified epidemiologists and statisticians making
such estimates, there is little reason to assume that the values are in
error. Thailand has perhaps the best sentinel surveillance program in the
developing world, with formerly biannual and now annual samples drawn from
five risk groups: intravenous drug users, commercial sex workers (formerly
two groups, but now one), men attending sexually transmitted disease clinics,
women attending antenatal care clinics, and blood donors (for more details,
Ungchusak, K., Htoon, M.T., and Detels, R. HIV sentinel
surveillance in Thailand - An example for developing countries. Asia Pacific
Journal of Public Health 8(1):20-26, 1995).
In addition, the Royal Thai Army routinely samples young men entering
the military and reports their HIV status (for additional information,
see: Mason, C.J., Markowitz, L.E.,
Kitsiripornchai, S., Jugsudee, A., Sirisopana,
N., Torugsa, K., Carr, J.K., Michael, R.A., Nitayaphan, S., and McNeil, J.G. Declining prevalence of HIV-1 infection in young Thai men. AIDS 9(9):1061-1065,1995).
The samples from both the sentinel surveillance program and the Thai military
are regularly gathering from all provinces, offering a detailed view of
both national and local HIV occurrence.
While estimating AIDS cases and deaths is important from a clinical
point of view, the future impact of the epidemic is more completely understood with knowledge of HIV
infections. Unfortunately, HIV is only detected by testing for the presence
of antibodies, using blood, or sometimes saliva or urine. Since such testing
is often done in confidential or anonymous settings and therefore not reported,
and many people are never tested, the full extent of the epidemic can only
be estimated. Such estimates are derived using complex mathematical models
which use data from the sentinel surveillance program, the Thai military,
regional surveys, and reported AIDS cases and deaths. While the HIV/AIDS
figures in many developing countries may not be highly accurate, the estimates
in Thailand are probably among the best, and have been very useful for
promoting public awareness and guiding intervention and prevention policies.