Two species of cryptosporidium infect laboratory mice (Mus musculus) namely C. muris and C. parvum which inhibitant of gastric and intestinal mucosa respectively C. parvum and in rare occasions C. muris are pathogenic for humans particularly in immunocompromised individuals. The animals harbor cryptosporidium organism could be a potential sources of infection for humans and susceptible species. In the present study to survey the occurrence of cryptosporidium in the laboratory mice, tissue sections stained with Haematoxylin and Eosin and Mepacrine staining methods were carefully examined and the positive specimens were further stained with Modified Ziehl Neelsen technique recommended for identification of cryptosporidial organisms. 100 conventional and BALB/C laboratory mice from six research and educational centers were studied for the presence of cryptosporidium in the gastric and intestinal mucosa. Sixty-three out of hundred (63%) of animals examined were infected with cryptosporidium organisms: gastric cryptosporidiosis due to C. muris nine out of hundred (9%), intestinal cryptosporidiosis caused by C. parvum thirty-four out of hundred (34%) and both cryptosporidiosis of stomach and intestine twenty out of hundred (20%). With the exception of gastric cryptosporidiosis, cryptosporidiosis of intestine is very mild to moderate. It is concluded that a high percentage of laboratory mice harbors cryptosporidium organisms. The infected animals not only could be a source of infection for laboratory animals but also in many instances such the animals may not a suitable one for research purposes.
