Abstract
Objective: A prediction of the number of HIV-infected persons through sexual contacts in Japan until the end of 2010 was attempted under the scenarios of future parameters using a system model.
Material and Methods: HIV/AIDS surveillance reports until 1999 in Japan were available. A system model was based on one of two scenarios: one is that the parameters after 2000 in the system model will be constant (basic scenario), and the other is that those will be changed due to countermeasures against HIV/AIDS (countermeasure scenario). In the countermeasure scenario, the frequency of sexual contacts will decrease by 5 percent, condom use will increase from 50% to 55%, 10% of sexually active persons will be non-active, detection rate of HIV infection will increase from 20% to 30%, and, the decrease in the rate of sexual contact due to the diagnosis of HIV infection will be from 20% to 10%.
Results: Under the basic scenario, the prevalence of Japanese HIV-infected persons at the end of 2010 was predicted to be 8, 700 among males and 3, 500 among females through heterosexual contacts, and 35, 000 through homosexual contacts. The ratio of the prevalence under the countermeasure scenario to under the basic scenario was 81% among males an 77% among females through heterosexual contacts, and 66% through homosexual contacts. The sensitivity analysis showed that the prevalence under the basic scenario was unstable, and that the ratio of the prevalence under the countermeasure scenario to under the basic scenario was stable.
Conclusion: The predicted prevalence of Japanese HIV-infected persons through sexual contacts at the end of 2010 under the scenarios was shown.
