Simulation of the Heterosexual HIV/AIDS Epidemic in Japan by a Fuzzy Mathematical Model

A study with a mathematical model was conducted for the objectives of analyzing heterosexual human immunodeficiency virus (HIV) transmission in Japan and identifying effective countermeasures against HIV/acquired immunodeficiency syndrome (AIDS) epidemics in communities in which the transmission is mainly through commercial sex workers (prostitutes). A fuzzy mathematical model which examined 4 groups (highly and moderately sexually active males, and highly and moderately sexually active females) was developed to simulate the heterosexual HIV/AIDS epidemic in Japan. The simulation generated bell-shaped epidemic curves for the numbers of male and female AIDS cases. At the early stage of the epidemic, the calculated incidence of male and female AIDS cases was similar to the reported incidence in each sex, respectively, in Japan. The results obtained with the scenario which assumed rapid spread of condom usage among highly sexually active females disclosed that this countermeasure had the biggest effect. The results obtained with either the scenario which assumed the spread of condom usage among males who travel outside of the community, or which assumed a decrease in the number of commercial sex workers from other communities, disclosed that these countermeasures had little preventive effect. The results suggest that countermeasures designed to decrease heterosexual HIV transmission inside of the community are the most effective, even if the inflow of HIV from outside communities does not decrease.