Survey of Cryptosporidium oocysts from adult cattle in a slaughter house.

Cryptosporidian oocysts were surveyed in rectal stools of adult cattle which were carried into slaughterhouse from April 1995 to July 1996. We morphologically and histologically investigated oocysts, and experimentally infected the isolated oocysts to mice and rats. Cryptosporidian oocysts were detected from 24 of 512 cattle (4.7%). They were spherical or ovoid, and the size was 7.0-7.9 x 5.3-6.1 microm. Mice and rats inoculated orally with 10(5)-10(7) oocysts became infected and discharged oocysts in the feces for a period of more than two months. Developing parasites were detected from the stomach of mice, and not detected from the other digestive tract. From these findings, present isolates from cattle were identified as Cryptosporidium muris.