Cryptosporidiosis is caused by infection with the single-celled parasite (not bacterium) Cryptosporidium parvum. It is a protozoan parasite that is transmitted by fecal-oral contamination. These protozoa invade the apical surface (brush border) of the enterocyte in the distal small intestine and proximal colon and form parasitophorus vacuoles where development occurs. Infection results in crypt and submucosal inflammation, necrosis of microvilli, villous atrophy and decreased mucosal enzyme activity. This results in decreased absorptive ability of the intestinal tract, fermentation of nutrients within the lumen and osmotic diarrhea. Cryptosporidiosis is usually seen in calves between one and two weeks of age. It is very rare in animals older than a month old, because by this age most animals will have become immune to infection.
• Diarrhea – profuse watery and green, occasionally bloody.
• Colic and pain.
• Depression, loss of appetite and weight loss.
• Many infected calves will not develop diarrhea, the reason for this is not known in many cases cryptosporidia is seen with other diseases, particularly rotavirus. In this case disease is often more severe with more affected calves
• Weight loss
• Treatment cost