Fatal Intestinal Coccidiosis in a Three-Week-Old Buffalo Calf (Bubalus bubalus)
Abstract The water buffalo (Bubalus bubalus) is important to the economy of several countries, especially in Asia and South America. Little is known regarding the impact of coccidiosis in buffaloes. Cattle and buffaloes are considered to have common species of Eimeria, but critical cross-transmissions have not been made because it is difficult to raise these hosts coccidian free. Clinical coccidiosis was confirmed post mortem in a 22-day-old buffalo calf that died after a 3- to 4-day illness. Oocysts morphologically identical to Eimeria bareillyi were found in the feces and in sections of small intestine. Oocysts were often pyriform, sometimes with asymmetrical sides. The shorter end was flattened and approximately 5–6 μm wide. Unsporulated oocysts in feces were 23.2–29.5 × 16.5–22 μm, with an average of 27.2 × 19.3 μm. Schizonts, gamonts, and oocysts were identified in sections of small intestine where they were located in enterocytes of the jejunum and ileum. No coccidian stages were seen in sections of colon. This is one of the first confirmed cases of clinical coccidiosis in water buffalo.
Development of gametocytes and second asexual generation stages of Eimeria auburnensis in calves.
Thirty calves were used to study the endogenous stages of Eimeria auburnensis, and 6 additional calves were employed to investigate the patent and prepatent periods. Second-generation schizonts and gametocytes occurred in a subepithelial location in cells of mesodermal origin in the distal portion of the villi. Trophozoites and immature schizonts of the second generation were found in calves killed 10 and 12 days after inoculation. Mature second-generation schizonts, observed in 12-, 14-, and 15-day infections, had 4 to 11 merozoites. A number of host cells harbored gametocytes in addition to the mature second-generation schizonts. Gametocytes were first seen on the 14th day after inoculation. Macrogametes had large nuclei and nucleoli, and many had a basophilic body near the nucleolus. Cytoplasmic granules first appeared at 16 days after inoculation; the oocyst wall began to form at 17 days after inoculation, and at 18 and 19 days many fully formed oocysts were seen. Only the youngest macrogametes, seen at 14 days after inoculation, were Feulgen-positive; all others were Feulgen-negative. PAS-positive granules were seen in increasing numbers in macrogametes beginning on the 15th day after inoculation. In oocysts the entire cytoplasm appeared strongly PAS-positive. Microgametocytes were first distinguishable in 14-day infections. During early development the nuclei were randomly arranged, but in more advanced microgametocytes, the nuclei were arranged at the periphery of internal compartments, whose interior had lightly stained residual material. Microgametes formed in rows at the surface of the compartments; later they were arranged in whorls. Mature microgametocytes were seen in abundance in 18and 19-day infections. Microgametocytes were PAS-positive in areas corresponding to the location of microgametes. Basophilic crescent-shaped bodies were observed in the parasitophorous vacuoles of host cells parasitized by macrogametes and microgametocytes. These were PAS-negative and Feulgen-negative; their significance is unknown. In 6 calves, the mean prepatent period for E. auburnensis was 17.5 days and the patent period averaged 3.3 days. The sexual stages of Eimeria auburnensis have been briefly described (Hammond, Clark, and Miner, 1961; Davis and Bowman, 1962). Recently an account of the development of the first-generation schizonts of this species was given (Chobotar, Hammond, and Miner, 1969). In the present paper we report the occurrence of a previously undescribed second generation of schizonts and present additional information concerning the development of the
Experimental Eimeria alabamensis infection in calves.
Four groups of three conventionally reared 2-month-old bull calves were inoculated with 10 million to 400 million sporulated oocysts of Eimeria alabamensis isolated from Swedish calves which had diarrhoea while at pasture. Their appetite, clinical condition, growth rate and the dry matter content of their faeces were compared with those of three similar but uninoculated calves. The prepatent period was 6-8 days, and the period during which large numbers of oocysts were excreted was 2-7 days. In two of the inoculated calves only a slight softening of the faeces was observed. The other ten calves developed watery diarrhoea, had a poor appetite and appeared depressed. The clinical signs were most severe in the calves which received the highest doses and included signs of abdominal pain and a reluctance to rise. The growth rates of the infected calves were significantly reduced for 18 days after inoculation, and 71 days after inoculation they had not compensated for this period of reduced growth rate.