DIFFERENTIATION BETWEEN HUMAN AND ANIMAL STRAINS OF CRYPTOSPORIDIUM-PARVUM USING ISOENZYME TYPING

Isoenzyme typing was used to study a number of oocyst isolates of Cryp tosporidium parvum from different geographical locations and of human or animal origin. All isolates showed identical enzyme motility when g lucose phosphate isomerase (GPI;23 isolates tested) or lactate dehydro genases (LDH; 20 isolates tested) was assayed. However, two isoenzyme forms were observed with phosphoglucomutase (PGM; 9 animal isolates sh owed one form, while 8/9 human isolates showed a second form) and hexo kinase (HK; 4 human isolates showed one form and 6 animal isolates sho wed a second form). Thus, PGM and HK each exhibit 2 isoenzymes corresp onding to 2 parasite populations associated with separate hosts. The d ata from this study, plus supportive evidence obtained by different me thods and by independent researchers, lend support to the hypothesis t hat separate cycles of transmission of C. parvum may exist within huma n and animal hosts.