title: Morphology is not a reliable tool for delineating species within Cryptosporidium.
abstract: Within the coccidia, morphological features of the oocyst stage at the light microscope level have been used more than any other single characteristic to designate genus and species. The aim of this study was to conduct morphometric analysis on a range of Cryptosporidium spp. isolates and to compare morphological data between several genotypes of C. parvum and a second species C. canis, as well as a variation within a specific genotype (the human genotype), with genetic data at 2 unlinked loci (18S ribonucleic deoxyribonucleic acid and HSP 70) to evaluate the usefulness of morphometric data in delineating species within Cryptosporidium. Results indicate that morphology could not differentiate between oocysts from C. parvum genotypes and oocysts from C. canis, whereas genetic analysis clearly differentiated between the two. The small size of the Cryptosporidium spp. oocyst, combined with the very limited characters for analysis, suggests that more reliance should be placed on genetic differences, combined with biological variation, when delineating species within Cryptosporidium.
authors.affiliation: Division of Veterinary and Biomedical Sciences, Murdoch University, Perth, Western Australia 6150, Australia.
authors.forename: Abbie
authors.initials: A
authors.lastname: Fall
authors.forename: R C Andrew
authors.initials: RC
authors.lastname: Thompson
authors.forename: Russell P
authors.initials: RP
authors.lastname: Hobbs
authors.forename: Una
authors.initials: U
authors.lastname: Morgan-Ryan
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D003458:Cryptosporidium / Q000145:classification* / Q000235:genetics / Q000648:ultrastructure; D016054:DNA, Protozoan / Q000737:chemistry; D004275:DNA, Ribosomal / Q000737:chemistry; D004285:Dogs; D005243:Feces / Q000469:parasitology; D005838:Genotype; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008394:Marsupialia; D010641:Phenotype; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D018840:HSP70 Heat-Shock Proteins; D012337:RNA, Ribosomal, 18S