The detection of a novel type of Cryptosporidium andersoni oocyst in cattle in Japan.

Cryptosporidium muris, found in rodents and cattle, has been recognized as a valid species. However, this organism from cattle was recently separated from C. muris infecting rodents based on molecular data and a transmission study. As a consequence, it has been proposed as a new species, C. andersoni. More recently, C. andersoni, which has infectivity to rodents, was detected in cattle in Japan, where it has been designated as a novel type. However, isolates from cattle in Japan have not been analyzed genetically, and therefore it remains unclear whether a novel type of C. andersoni is distributed widely in Japan. In the present study, we detected Cryptosporidium oocysts from cattle reared in a different area than those examined previously in Japan. These were identified by molecular analysis and experimental transmission. The 18S ribosomal RNA gene sequence of the isolate examined was identical with that of C. andersoni reported previously, and the isolate was successfully transmitted to severe combined immunodeficiency mice. Therefore, the isolate from cattle examined in the present study was identified as a novel type of C. andersoni. Our data suggests that it is widespread in cattle in Japan.