Dynamics of HIV transmission among men who have sex with men in Taiwan: a mathematical modeling study

Abstract

Background In Taiwan, the human immunodeficiency virus (HIV) is primarily transmitted among men who have sex with men (MSM). Nonetheless, detailed epidemiological studies considering heterogeneity in susceptible and infectious populations remain lacking. Therefore, we modeled the HIV epidemic with heterogeneity, estimated parameters, and predicted future infection trends in order to better understand the HIV transmission dynamics among MSM. Methods We devised a computational approach to accurately estimate the number of infectious individuals during early surveillance years in Taiwan using monthly data of newly diagnosed patients with HIV from January 2005 to December 2006. Subsequently, using annual incident cases from 2005 to 2019, we estimated the susceptibility rate, transmission rates, and duration of risk and conducted short-term forecasts of HIV infection in the MSM population through mathematical modeling based on the susceptible-infected-removed model. Parameters and their values, such as the infection rates of HIV and acquired immunodeficiency syndrome (AIDS), and the removal rates of HIV and AIDS, were also estimated. Results A total of 850 infectious individuals with HIV were identified in 2005. From 2005 to 2019, approximately only 0.68% of Taiwan’s male population were estimated to be susceptible to HIV infection via MSM. The transmission rate did not significantly differ between individuals with HIV and individuals with AIDS (0.0110 and 0.107 per 10,000 individuals, respectively). The average duration of infection was 4.5 years between infection and the onset of AIDS and 2.1 years between the onset of AIDS and death. In 2019, the proportion of infectious infected individuals continuously decreased. By 2026, it is estimated that only 11.85% of individuals with HIV and 10.21% of AIDS individuals will be infectious. Conclusions Our study presents a new dynamic mathematical model for estimating infectious HIV cases among MSM in Taiwan. By accounting for heterogeneity of infectious HIV/AIDS within the MSM population, it was possible to effectively estimate the number of infections during early surveillance years and implement concentrated measures, thereby reducing infectious HIV/AIDS cases and contributing to the overall reduction in HIV/AIDS. We could better identify the target population and implement effective intervention measures at appropriate times.