Intestinal Cryptosporidiosis in a Cat

Cryptosporidiosis has been reported in calves, lambs, man, pigs, and cats [l-91. In most species, they are associated with diarrhea. Transmission and scanning electron microscopy have demonstrated different stages of cryptosporidia free in the lumen and attached to the microvillus border of the intestinal epithelium [7]. This report describes an intestinal infection by cryptosporidium. A five-year-old male domestic longhair cat with clinical signs of anorexia, weight loss, and persistent diarrhea for 2% months was admitted for treatment. Clinical laboratory findings revealed packed cell volume 37.0%, serum alanine aminotransferase 47.7 IU/L, alkaline phosphatase 1.15 IU/L, serum aspartate aminotransferase 16.8 IU/L, lipase 0.93 U/ml, amylase 332 IU/L, and creatinine 1.3 mg/dl. The feline leukemia virus fluorescent antibody test on blood was negative. Examination of a Giemsa-stained blood smear did not reveal Haemobartonella organisms. Fecal flotation and direct microscopic examination of feces were negative for ova or parasites, and aerobic bacterial culture of a fecal sample was negative for known bacterial pathogens. The cat did not respond to treatment with Aziomycin (Schering Corporation, Kenilworth, N.J.), B- 12, B-plex, fluids, and lincocin. Exploratory surgery revealed enlarged mesenteric lymph nodes, dilatation, and marked thickening of the small intestine and cecum. The cat was euthanatized and necropsied immediately. Specimens for light microscopy were fixed in buffered neutral 10% formalin, sectioned at 6 pm, and stained with hematoxylin and eosin (HE). For transmission electron microscopy, appropriate tissue sections in paraffin blocks were deparaffinized, soaked in xylene, and rehydrated by passing through descending concentrations of alcohol. The tissues were transferred to phosphate buffer and fixed finally in osmium tetroxide and embedded in epon. Ultrathin sections were cut and stained with uranyl acetate and lead citrate and examined and photographed with an electron microscope. Grossly, the mesenteric portion of the small intestine and cecum were dilated and thickened markedly. Mesenteric lymph nodes were enlarged. The abdominal cavity contained 20 to 30 ml of clear fluid and the liver was yellow and fatty. Histologically, the small intestinal lesions consisted of the fusion of villi, an increased number of goblet cells, and hyperplastic crypt epithelium with a few dilated cystic crypts containing necrotic cell debris (fig. 1). The lamina propria was infiltrated mildly with lymphocytes and neutrophils. Numerous round or ovoid organisms ranging from 1 to 3 pm in diameter were found free in the lumen and attached to the microvillus border of the villous epithelium and luminal epithelium of crypts (fig. 2). These organisms were concentrated more in crypts and the lower half of the villi. They scarcely were seen on the villous tips. The lesions in the cecum were limited to crypts and consisted of several dilated cystic crypts; the lumens of which contained mucus and necrotic cell debris. Few organisms were found attached to crypt epithelium. The hepatic lesions were primarily a mild diffuse fatty metamorphosis and bile stasis.