Pathogenesis of human and bovine Cryptosporidium parvum in gnotobiotic pigs.

To compare the pathogenesis of human genotype 1 (HuG1) and bovine genotype 2 (BoG2) Cryptosporidium parvum, neonatal gnotobiotic pigs were given 1-10 HuG1 or BoG2 oocysts. The prepatent and patent periods were significantly longer for HuG1 than for BoG2 C. parvum (prepatent, 8.6 vs. 5.6 days; patent, 16.6 vs. 10.3 days). BoG2-infected pigs developed significantly more severe disease than did HuG1-infected pigs. BoG2 parasites were seen microscopically throughout the intestines during the prepatent and patent periods. HuG1 parasites were only detected during the patent period in the ileum and colon but colonized the mucosal surface in significantly larger numbers than did BoG2. Moderate-to-severe villus/mucosal attenuation with lymphoid hyperplasia was seen throughout the intestines of BoG2-infected pigs, whereas lesions in HuG1-infected pigs were mild to moderate and restricted to the ileum and colon. These findings provide additional support for the hypothesis that human and bovine C. parvum genotypes may be separate species.