A MORPHOMETRIC COMPARISON OF 5 AXENIC GIARDIA ISOLATES

The length and width of trophozoites from axenic cultures of 5 Giardia isolates were measured both live and after fixation and Giemsa staining. These isolates, as named on the basis of host source, are classified as G. lamblia (3 isolates), G. felis (1 isolate) and G. caviae (1 isolate). The size of live, unstained trophozoites from the 5 isolates, measured without regard to the presence or absence of median bodies, showed only occasional significant differences in length. Statistically significant differences in length and/or width were observed for all comparisons when stained preparations of the isolates were compared. These size differences occurred between isolates assigned to different species and among the 3 G. lamblia isolates. These data and previously reported isozyme studies of these isolates most appropriately led to a re-examination of the presently used criteria for Giardia speciation.