chapter  6
4 Pages

Prokaryotic Parasites of Reptilian Blood Cells

Desser (1987) demonstrated by ultrastructure that inclusions in erythrocytes of Canadian anurans were rickettsiae and designated them Aegyptianella ranarum. Under light microscopy, the roughly spherical inclusions were 3-11 µm in diameter, densely stained when small, and bordered by a darker stained margin. In the smaller inclusions, “several closely packed rickettsiae arranged in parallel” were visible, while “lighter staining, filamentous material” was visible in the larger inclusions. Electron microscopy confirmed the rickettsial identity. Small inclusions were contained within a “membrane-bound vacuole in the cytoplasm of the erythrocyte.” A “moderately dense, irregularly arranged granular matrix” was contained within them, associated with “large spherical bodies of variable density and smaller patches of electron dense material.” Within the granular matrix, rod-shaped microorganisms were embedded. In larger inclusions, there were “90-120 closely spaced organisms, usually arranged in parallel, within a lucent matrix consisting of scattered granular material.” Their rickettsial identity was evident at higher magnifications, and their dimensions were “1-1.7 µm in length by 200-300 nm in diameter” (Desser, 1987).