Epidemiology of amebiasis around the COVID-19 pandemic period in Japan

Amebiasis cases in Japan are reported to the government according to the Infectious Diseases Control Law. Previous studies have shown significant reductions in total case numbers after 2018 and during the COVID-19 pandemic. This study aimed to clarify the recent trends of amebiasis in Japan, including during the pandemic period, with details on places of infection and disease types, using government surveillance data from January 1, 2001, to December 31, 2022. Multiple comparisons by Dunnett’s test were performed to compare case numbers of three time periods (2015-2017, 2018-2019, and 2020-2022). Significant decreases in reported amebiasis cases were observed in 2018 (24.5%) and in 2020 (45.3%). This downward trend was observed regardless of place of infection (domestic or imported) and disease type (intestinal or extraintestinal). Male cases predominated, with most male cases in their 40s and 50s.Most cases of amebiasis have been reported in metropolitan areas. These results suggest that the decreased case numbers during the COVID-19 pandemic were due to not only the travel ban, but less socioeconomic activity. Furthermore, the epidemiology of amebiasis is similar to that of HIV infection in Japan, but the case numbers of amebiasis have not yet recovered, showing a different trend from HIV infection and syphilis.