Dynamic Model In The Propagation Analysis Of High-risk Groups Of Aids In China Five

Introduction Different social, cultural, and political aspects of HIV/AIDS may alter the dynamics of infection. A generalized epidemic of HIV, predicted in 2003, has not yet occurred in China, most likely due to because the implementation of a series of effective interventions. However, the HIV/AIDS epidemic is complex and evolving and the long-term future of epidemic is not certain. China urgently needs to understand the epidemic trends and quantitatively evaluate the effect of intervention strategies and measures by developing suitable compartmental dynamic models.Objective To analyze dynamic characteristics and long-term HIV epidemic trends among high-risk populations under current intervention strategies and measures; to determine the basic reproductive number (Ro) of HIV transmission; to analyze the impact of several intervention strategies and measures on the HIV epidemic in order to inform how to better allocate limited resources to control the HIV epidemic.Methods Deterministic compartmental mathematic models based on nonlinear ordinary differential equations were developed to describe the likely long-term trends of the HIV epidemic and calculate R0. Some parameters were determined by Monte-Carlo simulation and Least Square method.Results Under current interventions, the weighted Ro was 1.610 (1.597～1.623) and the average R0 was 1.870 (1.856～1.884) among the men who have sex with men (MSM), female sex workers (FSWs) and their clients, and injection drug users (IDUs). The R0 for MSM was 4.60 (4.56-4.64),1.22 (1.21～1.23) for FSWs and their clients, and 0.420 (0.416～0.424) for IDUs. The Ro for HIV positive pregnant women is always less than 1. By 2015, the total cumulative number of living HIV cases would be 670,000, including 250,000 MSM,230,000 clients,47,000 FSWs, and 140,000 IDUs. In this time, the epidemic among MSM is expected to rise continuously, but that of clients is expected to plateau. The epidemic of IDUs is expected to go down continuously. Reinforcement of detection and voluntary counseling and testing (VCT) including expanding coverage, education, and increased condom promotion could decrease the growth of the HIV epidemic among MSM. Promotion of condom use could also decrease the growth of the HIV epidemic among heterosexual populations. Expansion of needle exchange programs is likely to stem the HIV epidemic among IDUs.Conclusions The Chinese HIV epidemic is rising slowly. Prevention and control measures should focus on populations with high-risk sexual behavior. Intervention measures, such as condom promotion and needle exchange programs should be expanded in order to reduce Ro. Not only the coverage of VCT,s but also the quality of VCT need substantial improvements. Not only biological, but also social and behavioral aspects should be taken into account in developing HIV/AIDS transmission models.