Effect of diethyldithiocarbamate on Cryptosporidium parvum infection in immunosuppressed rats.

Diethyldithiocarbamate was the only immune modulator of 7 evaluated to show activity against Cryptosporidium parvum in immunosuppressed rats. The model was then used to assess the drug's activity further. When administered prophylactically, oral doses > or = 75 mg/kg/day significantly (P < or = 0.05) reduced the severity of ileal infection and doses > or = 300 mg/kg/day significantly (P < or = 0.05) inhibited infection of the biliary tract. When administered to rats with established infection, the drug significantly (P < or = 0.05) reduced the parasite burden in the ileum but was ineffective against biliary tract infection. The data suggest that diethyldithiocarbamate is effective for treating cryptosporidiosis of the small intestine but is probably ineffective against chronic cryptosporidiosis involving the large intestine or biliary tract.