Modelling TB-HIV co-infection and evaluating intervention strategies in Thailand.

The co-infection of Tuberculosis (TB) and Human Immunodeficiency Virus (HIV) remains a significant public health challenge both in Thailand and globally. This dual burden exacerbates disease severity, complicates treatment strategies, and increases mortality rates. In this study, we developed a mathematical model of TB-HIV co-infection to examine the dynamics of TB prevalence, HIV prevalence, co-infection prevalence and combined (aggregated) disease burden across Thailand. The model was calibrated using real-world incidence data of TB-HIV co-infection in the country. The global sensitivity analysis revealed that the transmission rates of TB and HIV had the most significant influence on the basic reproduction numbers, [Formula: see text]​ and [Formula: see text]​, highlighting critical targets for intervention. The model was further used to evaluate the potential impact of various intervention strategies on reducing the prevalence of TB, HIV, co-infection, and combined disease burden over the period 2022-2039. We found that increasing treatment coverage for TB patients reduces TB prevalence, while HIV prevalence and TB-HIV co-infection prevalence increase over time due to the prolonging the survival of HIV-positive individuals and improving case detection. Additionally, treating individuals co-infected with TB and HIV significantly lowers the prevalence of co-infections. Our findings further suggest that reducing the progression rates of both TB and HIV leads to more substantial and sustained reductions in TB prevalence, HIV prevalence, and TB-HIV co-infection prevalence in Thailand. Our findings also indicate that higher HIV acquisition among TB patients amplifies the burden of co-infection, whereas increased TB acquisition among HIV patients accelerates its progression. Therefore, targeting the dual burden of TB and HIV is essential for lower the prevalence of both diseases, protect vulnerable populations, and ultimately work towards eliminating the diseases as a public health threat.