CRYPTOSPORIDIOSIS IN BOVINE AND HUMAN HEALTH

Cryptosporidiosis, which is caused by Cryptosporidium parvum and was d iscovered in mice at the turn of the century, emerged as a frequently reported intestinal disease of animals and humans in the 1980s when it s zoonotic potential was recognized. In recent years, the public has b ecome aware of severe cryptosporidiosis because of its incidence in AI DS patients and because of massive outbreaks of cryptosporidial enteri tis among the general populace worldwide from contaminated drinking wa ter. Livestock and human wastes that were laden with oocysts of crypto sporidia have been incriminated in some cases. Intestinal cryptosporid iosis of livestock causes a brief diarrheal disease and probably does not hinder lifetime production in most cases. However, serious disease and deaths may sometimes result from complications from other pathoge ns and various other detrimental factors. Adolescent and adult cattle can carry C. parvum but probably do not shed large numbers of the para site. However, certain cattle of all ages shed billions of the apparen tly nonzoonotic Cryptosporidium muris, which also was first discovered in mice around the turn of the century. Cryptosporidium muris infects only the glands of the stomach (abomasum in cattle), usually causes n o overt illness, but retards acid production. Protein digestion in the abomasum probably is retarded, and, in fact, milk production in cows that are chronically afflicted with C. muris is reduced about 13%. Gro wing calves may be adversely affected also. Therefore, as concerns the dairy industry, the discussion of cryptosporidia involves efficient c attle agriculture, public health, and the environment.