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Cryptosporidium parvum

Tyzzer,[86] in 1907, was the first to describe an organism of this genus with a short account of Cryptosporidium muris in the gastric mucosa of laboratory mice. He identified the mode of transmission as faecal–oral, and provisionally classified the organism with the coccidia. A further report in 1912 by the same author demonstrated a similar parasite in the small intestine; as he was unable to cross-infect from one site to the other with the two organisms, he recognized that they were different species. This latter organism is probably C. parvum. For many years only these two species were recognized, but recently, there has been an explosion of understanding of the genus Cryptosporidium, and now 13 species are recognized, with the possibility that many more will be named. Current valid species are: C. muris, C. parvum, C. hominis, C. andersoni, C. wrairi, C. felis, C. canis, C. meleagridis, C. baileyi, C. galli, C. serpentis, C. saurophilum, and C. molnari.[87]Of …