Can Cryptosporidium Exposure Come From Cows?
That question came to my desk this morning. After a couple hours of research using the Internet I came to these conclusions:
- However, what little research I could find indicates that only a small percentage of beef and dairy cows seem to shed crypto oocysts. One study of 43 dairy cows even found none shedding.
- Nevertheless, if calves are born in shared calving paddocks or pens even very low levels of exposure to contaminated feces can serve as an infective dose causing cryptosporidiosis.
Many, many studies have documented the shedding behavior of bovine calves with cryptosporidiosis. Given the huge numbers present in a preweaned calf-rearing environment and the low number of oocysts needed for an infective dose we can reliably conclude that reducing the spread of the disease among calves is likely to be the most cost-effective approach to controlling crypto.
So, forget about crypto coming from cows? No, not a good idea. Maintaining clean calving facilities will reduce the probability of those few shedding cows providing a steady supply of infected calves for the calf-rearing housing.