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Survey investigating homosexual behaviour among adult males used to estimate the prevalence of HIV and AIDS among men who have sex with men in Japan.

BACKGROUND
This study investigated the prevalence of male homosexual behaviour among adult men and of HIV and AIDS among men who have sex with men (MSM) and non-MSM in Japan.


METHODS
An anonymous self-administered postal questionnaire, and national HIV and AIDS notifications.


RESULTS
Same-sex sexual experience was reported by 2.0% of respondents. The prevalence of HIV and AIDS was 0.8818% among MSM and 0.0130% among non-MSM, indicating that HIV and AIDS are 68 times more prevalent among MSM.


CONCLUSION
Our findings underestimate homosexual and HIV prevalence due to several methodological limitations. The high prevalence of HIV and AIDS among MSM in comparison with non-MSM indicates the urgent need to prioritise funding and programs targeting MSM in Japan.