06/09/2025
寄生虫学教室の論文が国際誌 International Journal for Parasitology (IJP)の表紙に掲載されました！
一般にTaenia属条虫は食肉目を終宿主としますが、有鉤条虫Taenia soliumは例外的に霊長目であるヒトのみを終宿主とします。
ではなぜ有鉤条虫はヒトのみを終宿主とするようになったのでしょうか？その進化史の解明に迫る論文です！
（写真は有鉤条虫の中間宿主であるニホンイノシシです）
Our paper has been featured on the cover of the International Journal for Parasitology (IJP)!
While most Taenia tapeworms use carnivores as definitive hosts, the pork tapeworm Taenia solium is exceptional — it uses only humans, a primate. How did this parasite evolve to depend solely on humans? Our paper delves into the evolutionary history!
Reference
Hayashi, N., Kuwamoto, R., Okada, M., Suzuki, K., Hoketsu, T., Kelava, S., Ohari, Y., Okamoto, M., Yagi, K., Nonaka, N., Nakao, R., 2025. Phylogenetic characterization of the pork tapeworm Taenia solium in Japan: implications for the enigmatic evolutionary history. Int. J. Parasitol. 55, 497-508. doi: https://doi.org/10.1016/j.ijpara.2025.04.009
Story behind the cover
August (55:10)
On the origins of Taenia solium: how did humans acquire this tapeworm?
The morphological similarity of Taenia solium to African Taenia species has led to the “Out of Africa” hypothesis, which posits a sub-Saharan African origin for the parasite with subsequent dispersal accompanying human migration. In this study, genetic analyses of cysticerci identified in Japanese wild boars from Nagano Prefecture, Japan – a region generally considered non-endemic, revealed that they possess a haplotype distinct from haplogroups previously reported in Asia, Africa/America, and Bhutan. Remarkably, the Japanese haplotype diverged first from other haplogroups likely in the Early Pleistocene, long before human dispersal out of Africa. These findings suggest that the “Out of Africa” hypothesis may warrant reconsideration. Modern humans could have acquired T. solium in multiple parts of the Palearctic from previously unidentified definitive hosts.
Reference
Hayashi, N., Kuwamoto, R., Okada, M., Suzuki, K., Hoketsu, T., Kelava, S., Ohari, Y., Okamoto, M., Yagi, K., Nonaka, N., Nakao, R., 2025. Phylogenetic characterization of the pork tapeworm Taenia solium in Japan: implications for the enigmatic evolutionary history. Int. J. Parasitol. 55, 497-508. doi: https://doi.org/10.1016/j.ijpara.2025.04.009
Original image courtesy of Naoki Hayashi, Hokkaido University, Japan.
