Isoenzyme Electrophoresis of 30 Isolates of Giardia from Humans and Felines

Thirty isolates of Giardia duodenalis from humans and felines were compared by isoenzyme electrophoresis. Using 10 enzyme systems, 13 different zymodemes were distinguished. The majority of zymodemes could be divided into two groups: one group comprising human and feline isolates with worldwide geographic distribution; the other group containing human isolates restricted to Western Australia. A number of isolates showed multiple-banded patterns and the genetic significance of these findings is discussed. The marked heterogeneity of G. duodenalis demonstrated in this study is considered in relation to the epidemiology of giardiasis. The findings are consistent with felines serving as a reservoir of infection to humans.