title: Cryptosporidium hominis n. sp. (Apicomplexa: Cryptosporidiidae) from Homo sapiens.
abstract: The structure and infectivity of the oocysts of a new species of Cryptosporidium from the feces of humans are described. Oocysts are structurally indistinguishable from those of Cryptosporidium parvum. Oocysts of the new species are passed fully sporulated, lack sporocysts. and measure 4.4-5.4 microm (mean = 4.86) x 4.4-5.9 microm (mean = 5.2 microm) with a length to width ratio 1.0-1.09 (mean 1.07) (n = 100). Oocysts were not infectious for ARC Swiss mice, nude mice. Wistar rat pups, puppies, kittens or calves, but were infectious to neonatal gnotobiotic pigs. Pathogenicity studies in the gnotobiotic pig model revealed significant differences in parasite-associated lesion distribution (P = 0.005 to P = 0.02) and intensity of infection (P = 0.04) between C. parvum and this newly described species from humans. In vitro cultivation studies have also revealed growth differences between the two species. Multi-locus analysis of numerous unlinked loci, including a preliminary sequence scan of the entire genome demonstrated this species to be distinct from C. parvum and also demonstrated a lack of recombination, providing further support for its species status. Based on biological and molecular data, this Cryptosporidium infecting the intestine of humans is proposed to be a new species Cryptosporidium hominis n. sp.
authors.affiliation: Division of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, Western Australia 6150. unaryan@central.murdoch.edu.au
authors.forename: Una M
authors.initials: UM
authors.lastname: Morgan-Ryan
authors.forename: Abbie
authors.initials: A
authors.lastname: Fall
authors.forename: Lucy A
authors.initials: LA
authors.lastname: Ward
authors.forename: Nawal
authors.initials: N
authors.lastname: Hijjawi
authors.forename: Irshad
authors.initials: I
authors.lastname: Sulaiman
authors.forename: Ronald
authors.initials: R
authors.lastname: Fayer
authors.forename: R C Andrew
authors.initials: RC
authors.lastname: Thompson
authors.forename: M
authors.initials: M
authors.lastname: Olson
authors.forename: Altaf
authors.initials: A
authors.lastname: Lal
authors.forename: Lihua
authors.initials: L
authors.lastname: Xiao
mesh_terms: D000818:Animals; D002415:Cats; D002417:Cattle; D003457:Cryptosporidiosis / Q000469:parasitology* / Q000503:physiopathology / Q000635:transmission; D003458:Cryptosporidium / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D004285:Dogs; D005260:Female; D005838:Genotype; D005856:Germ-Free Life; D006801:Humans; D008297:Male; D051379:Mice; D033661:Oocysts / Q000235:genetics / Q000472:pathogenicity; D015800:Protozoan Proteins / Q000235:genetics; D051381:Rats; D013045:Species Specificity; D013552:Swine
chemical_list: D015800:Protozoan Proteins