Cryptosporidium parvum: experimental infections in aged Syrian golden hamsters.

Young (8-12 weeks) and aged (20-24 months) Syrian golden hamsters were intragastrically inoculated with Cryptosporidium parvum oocysts to compare the susceptibility to cryptosporidiosis between these two age groups. Oocyst shedding was significantly more intense in the aged than in the young hamsters. Moreover, parasite colonization of the small intestine was observed in the aged but not the young hamsters. Splenocytes from aged hamsters exhibited significantly lower T, B, and natural killer cell activities than did those from young hamsters. These studies suggest that susceptibility to cryptosporidial infections may be greater in aged individuals than has been previously realized.