Cryptosporidium is a single-celled protozoan parasite that can cause severe diarrhea in mammals with competent immune systems and death in those with compromised immune systems.  The parasite is shed in the infected animal’s feces and can be food- or water-borne.  The risk from Cryptosporidium is increased because billions of oocysts are shed from the host in an infective stage, only a single dose is needed to infect and the parasite can auto-infect the host without being re-ingested.  While there are various species, Cryptosporidium parvum is one species that seems to infect most mammalian hosts.

Traditional methods of reducing the incidence of Cryptosporidium have had minimal impact.  Drug therapy is hampered by the unique niche occupied in the intestine by the organism.  While cattle vaccines have reduced the number of organisms shed by an infected host, the numbers are still too high.  Disinfectants have not been successful because of the thick wall of the oocyst and filtration is difficult because of the oocyst’s small size.  Current research focuses on preventing infection or shedding of the Cryptosporidium oocyst and treating the feces to inactivate the oocyst.  Preliminary studies at OARDC suggest that intestinal microflora may play an important role in determining susceptibility.  Research is planned to evaluate the effectiveness of composting to deactivate the oocyst.