T9 in wild bears in Japan: Prevalence, species/genotype identification, and public health implications.

In Japan, the recent series of sporadic outbreaks of human trichinellosis caused by (Nematoda: Trichocephalida) has occurred owing to the consumption of raw or insufficiently cooked meat from wild bears. However, the infection status and molecular characteristics of larvae in Japanese wild bears remain poorly understood. This study investigated the prevalence of spp. in brown bears () from Hokkaido, and Japanese black bears () from three prefectures (Aomori, Akita, and Iwate) in northern Japan, between April 2019 and August 2022. larvae were detected in 2.5% (6/236) of the brown bears and 0.9% (1/117) of the Japanese black bears. Sequence analysis using two genetic loci, the internal transcribed spacer region of nuclear ribosomal DNA and the mitochondrial cytochrome oxidase subunit I gene, revealed that the larvae collected from the seven infected bears were identical to one of the two haplotypes of T9. The prevalence of T9 is low but is maintained in bears in the Hokkaido and Iwate prefectures suggesting that undercooked meat from these animals could cause human infection. Thus, continued health education campaigns are needed to raise awareness of the potential risk of trichinellosis among hunters, meat suppliers, consumers, and local governmental health agencies.