title: Cryptosporidium bovis n. sp. (Apicomplexa: Cryptosporidiidae) in cattle (Bos taurus).
abstract: A new species of Cryptosporidium, C. bovis, is described. Oocysts of C. bovis, previously identified as Cryptosporidium genotype Bovine B (GenBank AY120911), are morphologically indistinguishable from those of C. parvum. They are excreted fully sporulated and contain 4 sporozoites, but lack sporocysts. Oocysts measure 4.76-5.35 microm (mean = 4.89 microm) x 4.17-4.76 microm (mean = 4.63 microm), with a length-to-width ratio of 1.06 (n = 50). Oocysts were not infectious for neonatal BALB/ c mice, but were infectious for 2 calves that were previously infected with C. parvum. Oocysts were not infectious for 2 experimentally exposed lambs less than 1 wk of age and were not detected in 42 lambs 2-3 mo of age, but were detected in a 2-wk-old lamb. In an earlier study, 79 of 840 calves on 14 dairy farms in 7 states were found infected with the new species. Most calves were 2-7 mo of age and none exhibited signs of diarrhea. This new species has been found in 10 of 162 calves aged 9 to 11 mo on a beef farm in Maryland. Fragments of the 18S rDNA, HSP-70, and actin genes were amplified by PCR, and purified PCR products were sequenced. Multilocus analysis of the 3 unlinked loci demonstrated the new species to be distinct from C. parvum and also demonstrated a lack of recombination, providing further evidence of species status. Based on these biological and molecular data, we consider this highly prevalent Cryptosporidium that infects primarily postweaned calves to be a new species and propose the name Cryptosporidium bovis n. sp. for this parasite.
authors.affiliation: Environmental Microbial Safety Laboratory, Animal and Natural Resources Institute Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland 20705, USA. rfayer@anri.barc.usda.gov
authors.forename: Ronald
authors.initials: R
authors.lastname: Fayer
authors.forename: Mónica
authors.initials: M
authors.lastname: Santín
authors.forename: Lihua
authors.initials: L
authors.lastname: Xiao
mesh_terms: D000199:Actins / Q000235:genetics; D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology* / Q000635:transmission; D003457:Cryptosporidiosis / Q000469:parasitology / Q000635:transmission / Q000662:veterinary*; D003458:Cryptosporidium / Q000145:classification* / Q000235:genetics / Q000472:pathogenicity; D016054:DNA, Protozoan / Q000737:chemistry* / Q000302:isolation & purification; D004275:DNA, Ribosomal / Q000737:chemistry / Q000302:isolation & purification; D005243:Feces / Q000469:parasitology; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D033661:Oocysts / Q000648:ultrastructure; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012756:Sheep
chemical_list: D000199:Actins; D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D018840:HSP70 Heat-Shock Proteins; D012337:RNA, Ribosomal, 18S