Synonyms: Cytospermium zurnii, Eimeria bovis (pro parte), Eimeria canadensis (pro parte).
Hosts: Ox, zebu, water buffalo. Dahlberg and Guettinger (1956) reported E. zurnii in 2 white-tailed deer in Wisconsin, and Salhoff (1939) reported it in a roe deer in Germany. Wetzel and Enigk (1936) found it in a wisent in Germany. Honess and Winter (1956) recorded it from the elk in Wyoming.
Location: Cecum, colon, rectum, thruout small intestine.
Geographic Distribution: Worldwide.
Prevalence: This is one of the commoner coccidia of cattle. Boughton (1945) found it in 42% of 2492 bovine fecal samples in southeastern U.S., and Hasche and Todd (1959) found it in 26% of 355 cattle in Wisconsin. Supperer (1952) found it in 11% of 130 cattle in Austria. Yakimoff, Gousseff and Rastegaieff (1932) found it in 13% of 126 oxen in Uzbekistan. Marchenko (1937) found it in 20% of 137 cattle in the North Caucasus. Yakimoff (1933) found it in 18% of 41 oxen, 6% of 17 zebus and 37% of 30 water buffaloes in Azerbaidzhan. Tubangui (1928) found it in 3 of 28 zebus and 1 of 11 carabaos in the Philippines. Torres and Ramos (1939) found it in 38% of 156 cattle in Brazil. Ruiz (1959) found it in 1% of 100 adult cattle in the San Jose, Costa Rica abattoir.
Morphology: The oocysts have been described by Christensen (1941) among others. They are 15 to 22 by 13 to 18 u with a mean of 17.8 by 15.6 u. Their length-width ratio is 1.0 to 1.4 with a mean of 1.14. They are spherical to bluntly ellipsoidal, without a micropyle. The oocyst wall is thin, homogeneous, transparent, and colorless to faint greyish-lavender or pale yellow. An oocyst polar granule and residuum are absent. The sporocysts are 9 to 12 by 6 to 7 u, according to Yakimoff, Gousseff and Rastegaieff (1929). A sporocyst residuum is absent.
Complete sporulation occurs in 9 to 10 days at 12° C, 6 days at 15°, 3 days at 20°, 40 hours at 25° and 23 to 24 hours at 30 to 32.5° C; a few oocysts may sporulate at temperatures as low as 8° C in several months, but sporulation is not normal above 32° C (Marquardt, Senger and Seghetti, 1960).
Life Cycle: The endogenous stages of E. zurnii were described by Davis and Bowman (1957). Schizonts are found 2 to 19 days after experimental infection in the epithelial cells of the upper, middle and lower small intestine, cecum and colon. When mature they measure about 10 by 13 u and contain 24 to 36 merozoites. They lie distal to the host cell nucleus. Merozoites are first seen 7 days after infection. They are about 5 by 12 u, have their nucleus near the tapering end and contain 2 refractile globules. Davis and Bowman did not determine the number of asexual generations, but believed that there is more than one. The mature schizonts late in the cycle are slightly larger than the early ones.
Macrogametes are first seen 12 days after infection. They occur in the epithelial cells of the glands and to a lesser extent of the surface of the lower small intestine, cecum, colon and rectum, and rarely in the upper small intestine. They are about 11 by 14 u and contain 1 or 2 rows of plastic granules. Microgametocytes are first seen 15 days after infection in the same location as the macrogametes. They measure about 10 by 14 u when mature. Immature oocysts are first seen 12 days after infection.
Pathogenesis: E. zurnii is the most pathogenic coccidium of cattle. In acute infections it causes a bloody diarrhea of calves. At first the feces are streaked with blood. The diarrhea becomes more severe, bloody fluid, clots of blood and liquid feces are passed, and straining and coughing may cause this mixture to spurt out as much as 6 to 8 feet. The animal's rear quarters may look as tho they had been smeared with red paint. Anemia, weakness and emaciation accompany the dysentery, and secondary infections, especially pneumonia, are common. This acute phase may continue for 3 or 4 days. If the calf does not die in 7 to 10 days, it will probably recover.
E. zurnii may also be associated with a more chronic type of disease. Diarrhea is present, but there may be little or no blood in the feces. The animals are emaciated, dehydrated, weak and listless, with rough hair coats, drooping ears and sunken eyes.
The lesions of coccidiosis have been described by Boughton (1945) and Davis and Bowman (1952) among others. A generalized catarrhal enteritis involving both the small and large intestines is present. The lower small intestine, cecum and colon may be filled with semi-fluid, bloody material. Large or smaller areas of the intestinal mucosa may be eroded and destroyed, and the mucous membrane may be thickened, with irregular whitish ridges in the large intestine or smooth, dull grey areas in the small intestine or cecum. Diffuse hemorrhages are present in the intestines in acute cases, and petechial hemorrhages in mild ones.