Epidemiological investigation on cryptosporidiosis in dogs in Zhengzhou and experimental infection with oocysts derived from the dogs

To investigate the prevalence of Cryptosporidium in dogs,309 fecal samples,which were respectively collected from dog farms,pet markets in the suburban districts of Zhengzhou,laboratory animal rooms,pet hospitals and rural areas of Zhengzhou,were examined by flotation technique using the saturated sucrose solution and the modified acid-fast staining method.In addition,experimental infections with dog-derived oocysts in severe combined immunodeficiency(SCID) mice and Cryptosporidium-free puppies were performed.The results showed that the average infection rate was 2.59%.The dog infection rates on the dog farms,in the suburban districts and the laboratory animal rooms were 0.56%(1/179),10.53%(2/19),16.67%(5/30),respectively.No positive case was found in the dogs from the pet markets and the pet hospitals.Experimental infections demonstrated that the Cryptosporidium oocysts were not able to infect SCID mice and two-month-old non-immunocompetent dogs,but could infect immunosuppressed dogs.Through the tissue slice and the HE staining technique,Cryptosporidia were found in the duodenum and jejunum of the infected dogs.According to the shape of oocysts and the experimental-infection results,the Cryptosporidium oocysts derived from dogs were identified to be Cryptosporidium canis.