Comprehensive molecular epidemiology of Cryptosporidium species in Japan

Cryptosporidium species, causing diarrheal illnesses in humans and animals worldwide, are under investigation for their molecular epidemiology in Japan. The study focuses on detecting Cryptosporidium species in humans, animals, water, and the environment, revealing three species in people: C. parvum, C. meleagridis, and C. hominis. Subtype IIa of the C. parvum gp60 gene is prevalent, indicating potential zoonotic transmission. Animal studies identified sixteen species, mainly cattle and pets, with C. parvum (subtype IIa) common in cattle and C. canis and C. felis prevalent in pets. Additionally, C. bovis and C. ryanae were found in cattle and sika deer. Knowledge gaps exist, particularly in water and environmental source typing, with limited research revealing five species and five genotypes, suggesting a significant role of water in transmission. Further research is needed to understand the molecular diversity and transmission dynamics across humans, animals, water, and the environment in Japan. •Cryptosporidium species in Japan, especially C. parvum IIa, show zoonotic risks, highlighting the need to study human-animal links.•Water may spread Cryptosporidium spp. in Japan; research shows various species.•Investigating water infection routes is crucial.