Phylogenetic Analysis of the Hypervariable Region of the 18S rRNA Gene ofCryptosporidiumOocysts in Feces of Canada Geese (Branta canadensis): Evidence for Five Novel Genotypes

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Abstract
To assess genetic diversity inCryptosporidiumoocysts from Canada geese, 161 fecal samples from Canada geese in the United States were analyzed. Eleven (6.8%) were positive forCryptosporidiumspp. following nested PCR amplification of the hypervariable region of the 18S rRNA gene. Nine PCR products from geese were cloned and sequenced, and all nine diverged from previously reportedCryptosporidium18S rRNA gene sequences. Five sequences were very similar or identical to each other but genetically distinct from that ofCryptosporidium baileyi; two were most closely related to, but genetically distinct from, the first five; and two were distinct from any other sequence analyzed. One additional sequence in the hypervariable region of the 18S rRNA gene isolated from a cormorant was identical to that ofC. baileyi. Phylogenetic analysis provided evidence for new genotypes ofCryptosporidiumspecies in Canada geese. Results of this study suggest that the taxonomy ofCryptosporidiumspecies in geese is complex and that a more complete understanding of genetic diversity among these parasites will facilitate our understanding of oocyst sources and species in the environment.