548 J. Parasitol., 88(3), 2002, pp. 548–552  American Society of Parasitologists 2002 CLINICAL LARGE INTESTINAL COCCIDIOSIS IN CAMELS (CAMELUS DROMEDARIUS) IN THE UNITED ARAB EMIRATES: DESCRIPTION OF LESIONS, ENDOGENOUS STAGES, AND REDESCRIPTION OF ISOSPORA ORLOVI, TSYGANKOV, 1950 OOCYSTS Joerg Kinne, Mansoor Ali*, Ulrich Wernery, and J. P. Dubey† Central Veterinary Research Laboratory, P.O. Box 597, Dubai, United Arab Emirates. e-mail: jdubey@anri.barc.usda.gov ABSTRACT: Between January and March 2001, eight 4- to 8-wk-old camels (Camelus dromedarius) from 2 farms from Dubai area of the United Arab Emirates were submitted for necropsy examination. The camels had diarrhea of 2–5 days duration. Grossly, a severe diphtheroid-to-hemorrhagic colitis was seen in all animals. Gamonts, unsporulated oocysts, sporulating oocysts, and fully sporulated oocysts were present in the intestinal epithelium and the lamina propria. Fully sporulated oocysts contained 2 sporocysts and 4 sporozoites in each sporocyst. Oocysts from fecal samples resembled oocysts of Isospora orlovi. This is the first report of an isosporan parasite associated with hemorrhagic enteritis in the large intestine of any animal. Five species of Eimeria, Eimeria bactriani Levine and Ivens, 1970, Eimeria cameli Henry and Masson, 1932; Reichnow, 1952, Eimeria dromedarii Yakimoff and Matschoulsky, 1939, Eimeria pelle ´rdyi Prasad, 1960 emend. Pelle ´rdy, 1965, and Ei- meria rajasthani Dubey and Pande, 1963, and 1 species of Isos- pora, Isospora orlovi Tsygankov, 1950, have been reported from feces of camels (reviewed by Dubey and Pande, 1964; Levine and Ivens, 1970). The validity of some of these coccid- ian species is in doubt because the original descriptions were not complete and because their life cycles have not been com- pleted. Although there are several reports of diarrhea associated with Eimeria spp. infections in camels, most of them were based only on finding oocysts in feces (Iyer et al., 1968; Chineme, 1980; Yagoub, 1989). Henry and Masson (1932), Hussein et al. (1987), Iyer et al. (1968), and Kinne and Wernery (1997) re- ported schizonts and gamonts of Eimeria spp. in the small in- testine of camels. There is 1 report of I. orlovi-like oocysts, possibly associated with clinical coccidiosis in a 6-mo-old cam- el from India (Raisinghani et al., 1987). The objective of the present paper is to document clinical coccidiosis in camels associated with an I. orlovi-like parasite. MATERIALS AND METHODS Between January and March 2001, an outbreak of a camel calf dis- ease occurred in the Dubai area. Calves on 2 camel farms had diarrhea lasting 2–5 days, with no response to treatment with an anticoccidial (Baycox, 2.5% for 5 days, 0.2 ml/kg body weight). The mother camels, which were kept in large pens, received hay ad libitum and small amounts of grain pellets. When the calves became sick, they were kept in smaller pens together with their mothers. Adult camels were appar- ently normal. A total of 22 camel calf carcasses was submitted for necropsy ex- amination. All necropsies were performed within 1–5 hr after death. Pieces of intestines, liver, spleen, and lymph nodes were taken for mi- crobiological investigations using routine methods. The intestinal sam- ples were also tested for the growth of anaerobes. For histopathology, small pieces of all organs, including compartment 1 and stomach, as well as muscles and lymph nodes were fixed for 24 Received 31 July 2001; revised 26 October 2001; accepted 26 October 2001. *Camel Reproduction Laboratory, P.O. Box 9229, Nakhlee, Dubai, United Arab Emirates. ² To whom correspondence should be addressed.United States Depart- ment of Agriculture, Agricultural Research Service, Animal and Nat- ural Resources Institute, Parasite Biology, Epidemiology and System- atics Laboratory, BARC-East, Bldg. 1001, Beltsville, Maryland 20705-2350. hr in buffered neutral 10% formalin. Paraffin-embedded 5-m-thick sec- tions were stained with hematoxylin and eosin, or periodic acid Schiff hematoxylin. Oocysts were collected from feces of each camel by flotation in su- crose solution, suspended in 2.5% potassium dichromate, and examined microscopically. Oocysts from camels and sections of intestines from 3 camels were sent to the Parasite Biology, Epidemiology and Systematics Laboratory, Beltsville, Maryland, for further evaluation. Photographs of oocysts are from feces removed from colon of camel no. 269-01. RESULTS Lesions Severe pseudomembraneous-to-hemorrhagic colitis was found in 8 calves from 2 farms (Fig. 1A). Microscopically, the large intestinal mucosa was hemorrhagic and infiltrated by leu- kocytes, including neutrophils, eosinophils, and macrophages (Fig. 1A, C). Microbiological investigations, including anaero- bic cultures, did not detect any pathogenic bacteria. Endogenous stages Numerous coccidian stages (gamonts and oocysts) were lo- cated in the colon (Fig. 2) but not in the small intestine. Under the low power of the microscope, masses of coccidian stages were visible, often as a raised area (Fig. 1B). Only gamonts and oocysts were identified with certainty. All stages of gam- etogony and sporogony were present (Fig. 2). Multinucleated microgamonts-to-free microgametes were present among ma- crogamonts (Fig. 2A, B). Uninucleate macrogamonts-to-fully sporulated oocysts were seen. Oocysts contained 2 sporocysts, each with 4 sporozoites (Figs. 2G, 3F). Sporozoites in sections varied in size (Fig. 2G–I). In appropriately cut sections, there was a central nucleus and 2 eosinophilic bodies on either side of the sporozoite nucleus (Fig. 2H). One group of free zoites was also present (Fig. 2F). Sporozoites were 6–12 m in sec- tion (Fig. 2G, H). Description of oocysts Oocysts in different stages of sporogony were present in co- lon contents (Fig. 3). Immature unsporulated oocysts were ovoid and contained a granulated mass (sporont) occupying the entire oocyst. These immature unsporulated oocysts (Fig. 3A– C) were 22–23  17–23 m in size (n = 10). Unsporulated oocysts that appeared ready for sporulation were ovoid and had a central contracted sporont (Fig. 3D). These oocysts were 27– 33  20–27 m in size (n = 10).