Projection And Estimation Of HIV/AIDS Epidemic In Jiangsu Province

Background: Since the first AIDS case was reported in the United States in 1981, HIV/AIDS epidemic spread rapidly in the world, which had brought great effects to economic and social development. In the worldwide, the estimated number of persons who are living with HIV is 33.4 million in 2009. In Jiangsu Province, the first HIV case was reported in 1991, while the cumulative cases of HIV/AIDS reached to 4103 at the end of September, 2009. However, for the reasons of underreporting and delaying of report, there is a big gap between the reported cases and the real cases. Under this background, the estimation of HIV/AIDS positive cases has becomes one of the important ways to know the HIV/AIDS epidemic. Estimations and projections of HIV/AIDS epidemic status are recommended to describe the real situation for better policy, raising money and allocating it efficiently, evaluating the efforts of interventions. The mainly methods for HIV/AIDS cases estimation and prediction are as follows: Back-calculation method, Epidemodel, Workbook method, estimation and prediction package (EPP), Spectrum model, Asia epidemic model (AEM) and so on. Workbook method is popular in China, meanwhile, more and more attentions were paid to AEM and EPP recently. EPP model is designed by UNAIDS in 2001, it is a kind of simple epidemiological model which can produce basic popular curves of the AIDS epidemic model, it can get a best fitting curve with the development of time, and to reflect the adult infection rates. AEM is a process model, it was mainly by simulating HIV transmission at different groups to complete the evaluation. In AEM, the population is divided into 8 compartments (Clents, FSWs, Hi MSMs, Lo MSMS, MSWs, IDUs, GMs and GFs), and lots of formulas, designed in the AEM model, are used to calculate the number of newly infections, current infections and cumulative infections. AEM will produce a fit curve by adjusting the transmission probabilities and cofactors, and then generate useful outputs for policy making and programming.Objectives: To estimate and predict the current situation and epidemic tendency of HIV/AIDS in Jiangsu province using AEM and EPP models. To discuss the applicability of the two models in individual province of China and analyze the merit and demerit of AEM and EPP. Finally, the results of this study can contribute to the HIV/AIDS prevention and control policy making.Methods: According to EPP method, high-risk groups were identified, data bank was built up, in order to collect data and evaluate their quality. The results can be observed by EPP then. By the requirements of AEM, the data of population size, heterosexual behaviors, injection behaviors, same sex behaviors, epidemic factors, prevalence of each subgroups and migration parameters were collected and put into an EXCEL table, and then imported to AEM process, the process will find the best fit status and then produced the results.Results: Results from EPP method: the estimated number of current infections of HIV/AIDS was 12099, including 1904 IDUs, 5020 MSMs, 548 FSWs, 4098 Clients, with the other 529 cases, by the end of 2009. The predicted results of AEM: the numbers of newly infections, current infections, cumulative infections were 2395, 13610 and15806, and the epidemic would arise in future. The major mode of transmission was needle sharing before 2007, while the unprotected sex behavior, especially among MSWs & MSMs, became more and more important late. The projection results of 3 expanded intervention scenarios showed that ,the scenario1, 2, and 3 could avert 50907,55722 and 63633 newly infections at the end of 2020. Compared the estimated results of two models with the sentinel surveillance data of Jiangsu Province: the results showed that total number of current infections from EPP method and AEM were 12099 and 13610, while there were some difference in projecting numbers among subgroups.Conclusion: The number of current infections at the end of 2009 in Jiangsu estimated by AEM and EPP is very close, which is about 4 times than the HIV cumulative number from sentinel surveillance. AEM baseline projection results show that, if the intervention effect remained as it was in 2009, HIV/AIDS epidemic will arise in the coming years, especially among MSWs and MSMs, while intervention measures by different scenarios can largely avert newly infections. Accordingly, comprehensive intervention is needed and more effective intervention should be put to MSWs and MSMs.The AEM and EPP can accurately predict the development trend of AIDS epidemic in a certain extent, but the operation process is complicated, suitable for the places where have rich data.