Hepatitis E virus subtype 3f infections: rare but increasingly identified in Japan

Forty-two human-derived hepatitis E virus subtype 3f (HEV-3f) strains, identified in Japan between 1998 and 2024, were analyzed based on their genome sequences. Fourteen strains in the Kanto region and two in Mie Prefecture exhibited close genetic relatedness to each other but were distinct from European HEV-3f strains, suggesting possible endemic circulation in Japan. Conversely, seven strains from individuals without a history of travel shared identical nucleotide sequences with European HEV-3f, suggesting that these infections were potentially linked to imported pork. Comprehensive molecular and epidemiological studies are needed to clarify the relative contributions of local zoonotic transmission from domestic or wild animals versus foodborne introduction via imported pork products.