[Morphobiology and pathogenicity of Eimeria falciformis var. pragensis Cerna, Seraud, Mehlhorn & Scholtyseck, 1974 in mouse (Mus musculus)].

The life cycle of a species of murine Eimeria, isolated from a commercial source of mice is described using experimental infections. A pure strain was established starting from a single oocyst administered to Eimeria-free Swiss white mice. The prepatent period was 6 1/2 to 7 days, and the patent period lasted 6 to 10 days. Oocysts were subspherical or ovoid, with a smooth double-layered colourless membrane. Micropila was absent. The sporulated oocysts measured 15.7-25.1 x 14.1-22.0 microns (X780 = 21.3 x 16.9 microns). One to 4 polar granules were present. The oocyst residuum was absent. Sporocysts were ellipsoid, measured 11.5 x 6.3 microns (n = 780), with Stieda body and a compact subspherical sporocyst residuum. The sporozoites were elongated, 17.7 x 3.2 microns (n = 100), partially curled around each other. The endogenous stages were found only in the large intestine, with at least 4 generations of schizonts. Mature 1st generation schizonts, first seen 24 hr post-infection (HPI) measured 10.3 x 10.6 microns and had 8 to 25 merozoites 5.0-10.0 x 1.0-3.0 microns. Mature 2nd generation schizonts were first seen 48 HPI, measured 14.4 x 8.1 microns and had 8 to 20 merozoites 11.0-16.0 x 2.0-3.0 microns. Two forms of presumably 3rd generation schizonts appeared between 72 and 96 HPI: one measuring 13.9 x 8.5 microns, containing large merozoites (17.0-19.0 x 2.0-4.0 microns) and the other measuring 7.3 x 10.4 microns, where 6 to 10 merozoites (8.0-13.0 x 1.0-3.0 microns) were found. Fourth generation schizonts measuring 10.4 x 11.9 microns, with 26 a 48 or more merozoites (8.0-13.0 x 2.0-3.0 microns) were first seen at 132 HPI. Mature macro and microgamonts were first observed at 144 HPI. The sporulation of 72.0% of the oocysts in 2.0% (w/v) potassium dichromate at 23-24 degrees C occurred in 9 days. Usually the infected mice showed depression, anorexia, weight loss, diarrhea or dysentery, and dehydration. The clinical picture w as more pronounced at 6 to 10 days post-infection (DPI). Mortality was highest between the 8th and 13th DPI, with a peak at 9 DPI in groups which received 1.1 x 10(4) to 4.4 x 10(4) oocysts. Groups infected with 5.5 x 10(3), 8.8 x 10(4) or 1.76 x 10(5) oocysts showed different results. Epithelial destruction, edema, inflammation, necrotizing enteritis followed by glandular regeneration and realing were observed restricted to the large intestine. The isolated Eimeria was named E. falciformis var. pragensis based on its morphobiological characteristics.