An analysis of Japan's 2001-2022 amebiasis notifications found domestically acquired male cases rising before 2018, falling sharply during 2018-2020, and showing no significant post-2020 change. Reports concentrated among men in their 40s-50s and metropolitan areas, but surveillance data cannot determine whether behaviour, testing or reporting caused the shift.
Key findings
- Domestically acquired male cases rose by 59.5 per year before 2008 and 15.2 per year during 2008-2018, then fell by 219.0 per year in 2018-2020. The post-2020 slope of -16.9 per year was not significant (p=0.6532). Imported cases declined significantly only from 2019 to 2020.
Why this matters globally
The trend supports coordination between enteric and sexual-health surveillance, accessible testing without stigma, and monitoring whether low notifications reflect true decline or reduced diagnosis.
Thai researcher contribution
A Mahidol and MORU researcher joined the Japanese team analysing Japan's national data. This is cross-country scholarship, not a Thai patient survey.
Limitations to consider
Notifications depend on testing, diagnosis and reporting and may undercount disease. Individual behaviour, transmission route and testing access were unavailable. Prespecified knots may miss other changes, and reduced socioeconomic activity is an ecological hypothesis, not a proven cause.