Cryptosporidium ubiquitum is an emerging zoonotic pathogen. In the past, it was not possible to identify an association between cases of human and animal infection. We conducted a genomic survey of the species, developed a subtyping tool targeting the 60-kDa glycoprotein (gp60) gene, and identified 6 subtype families (XIIa–XIIf) of C. ubiquitum. Host adaptation was apparent at the gp60 locus; subtype XIIa was found in ruminants worldwide, subtype families XIIb–XIId were found in rodents in the United States, and XIIe and XIIf were found in rodents in the Slovak Republic. Humans in the United States were infected with isolates of subtypes XIIb–XIId, whereas those in other areas were infected primarily with subtype XIIa isolates. In addition, subtype families XIIb and XIId were detected in drinking source water in the United States. Contact with C. ubiquitum–infected sheep and drinking water contaminated by infected wildlife could be sources of human infections.
ABSTRACT. The standard method for determining the genotypes of Enterocytozoon bieneusi is based on the DNA sequence of the internal transcribed spacer (ITS) region of the rRNA gene. There are 81 genotypes with 111 genotype names: 26 genotypes have been identified exclusively in humans, eight have been identified in humans and in other hosts, 27 have been identified exclusively in cattle and pigs, six have been identified exclusively in cats and dogs, and 14 have been identified in miscellaneous hosts. Because none of these genotypes has taxonomic status and therefore do not adhere to the International Code of Zoological Nomenclature regarding naming, some genotypes have received multiple names, each different and in separate publications by different authors. Because of the proliferation of genotypes with overlapping names and multiple hosts the scientific literature has become confusing and difficult to efficiently utilize. To reduce confusion and provide guidance for future publications we tabulated all names, GenBank accession numbers, and author citations and propose that the first published name has precedence and should become the primary name used in all subsequent publications in which genotyping is based on ITS sequencing. In those publications the names and GenBank numbers that were submitted at later dates should also be provided by the authors as synonyms to aid readers and reviewers.
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