Cattle are major hosts of Cryptosporidium spp. Cryptosporidiosis in neonatal calves is associated
with retarded growth, weight loss and calf mortality, and zoonotic infections in
humans. In many areas, cow-calf glazing system is an important beef cattle rearing method
with distinct advantages in terms of cost and the labor required. However, few epidemiologic
studies of Cryptosporidium spp. have been conducted in this system, especially using
molecular diagnostic tools. To understand the transmission of Cryptosporidium spp. in a
grazing system, we followed cryptosporidiosis on a grazing farm in Osaki City, Miyagi
Prefecture, in northwest Japan for one year. Fecal samples were collected from Japanese
Black and Japanese Shorthorn cattle and examined by PCR-RFLP and sequence analyses.
Of 113 fecal samples collected in October 2010, 23 (20%) were positive for Cryptosporidium,
including 15 samples (13%) having C. bovis, 6 (5%) having C. ryanae, and 2 (2%) having
mixed infections of both species. Additionally, C. bovis or C. ryanae was detected on all
other sampling dates involving smaller numbers of animals. The infection rate of C. bovis
was significantly different among age groups, and calve-to-calve infection might be the
major route of cryptosporidiosis transmission in beef cattle. Interestingly, one animal had
C. bovis infection or re-infection for one year. Our results suggest that C. bovis and C. ryanae
are distributed in Japan, but might have low level of detection in grazing beef cattle.