Cryptosporidium Taxonomy: Recent Advances and Implications for Public Health

Abstract

There has been an explosion of descriptions of new species of Cryptosporidium during the last two decades. This has been accompanied by confusion regarding the criteria for species designation, largely because of the lack of distinct morphologic differences and strict host specificity among Cryptosporidium spp. A review of the biologic species concept, the International Code of Zoological Nomenclature (ICZN), and current practices for Cryptosporidium species designation calls for the establishment of guidelines for naming Cryptosporidium species. All reports of new Cryptosporidium species should include at least four basic components: oocyst morphology, natural host specificity, genetic characterizations, and compliance with the ICZN. Altogether, 13 Cryptosporidium spp. are currently recognized: C. muris, C. andersoni, C. parvum, C. hominis, C. wrairi, C. felis, and C. cannis in mammals; C. baïleyi, C. meleagridis, and C. galli in birds; C. serpentis and C. saurophilum in reptiles; and C. molnari in fish. With the establishment of a framework for naming Cryptosporidium species and the availability of new taxonomic tools, there should be less confusion associated with the taxonomy of the genus Cryptosporidium. The clarification of Cryptosporidium taxonomy is also useful for understanding the biology of Cryptosporidium spp., assessing the public health significance of Cryptosporidium spp. in animals and the environment, characterizing transmission dynamics, and tracking infection and contamination sources

Molecular Characterization of Bubaline Isolate of Cryptosporidium Species from Egypt

“…Oocysts of C. baileyi were inoculated orally into several animals to determine its host specificity. Mice and goats inoculated with C. baileyi oocysts did not become infected Xiao et al, 2004). Based on these theories and hence the detected Cryptosporidium oocysts in the examined young buffalo calf feces stained with Ziehl-Neelsen technique were morphologically similar to C. parvum oocysts.…”

“…Parasitol., 10 (4): 127-141, 2015 In accordance, during the present study, 823 bp fragments amplified from the 18S SSU rRNA gene could be noted after nested PCR reaction from buffalo's feces. Previous studies indicated the usefulness of the small subunit (SSU) ribosomal RNA genes as genetic markers for the specific identification of Cryptosporidium having relatively low intraspecific and relatively high interspecific sequence variation (Fayer et al, 2000;Xiao et al, 2004;Jex et al, 2007). Thus, they had been utilized in systematic (phylogenetic) investigations of Cryptosporidium providing the basis for the current classification of members within the genus (Morgan et al, 1999a;Xiao et al, 2004).…”

“…Despite that these results disagree with McLauchlin et al (2000) and others (Insulander et al, 2013;Friesema et al, 2012;Wang et al, 2011) who could identify C. parvum genotypes by 18S rRNA gene sequence, they confirmed the previous conclusion of many researchers who found the use of multi-loci analysis had better results with regards to Cryptosporidium genotyping (Abe and Teramato, 2012;Amer et al, 2010). Because their sequences had higher intraspecific variation than the ribosomal RNA gene regions (Morgan et al, 1999b), it was suggested that other Cryptosporidium genes targets should be used for amplification including the Cryptosporidium oocyst wall protein (COWP), 16S rRNA, Hsp70, Actin, β-Tubulin, gp60, microsatellites, minisatellites and extrachromosomal double-stranded RNA (Xiao et al, 2004;Caccio et al, 2005;Coklin et al, 2007). As well as the Internal Transcribed Spacers (ITS) of ribosomal DNA were useful for the detection of genetic variability within species (Chalmers et al, 2005;Schindler et al, 2005).…”

“…Therefore, molecular analyses had been widely used to characterize the genetic structure of Cryptosporidium parasites and assessment of their zoonotic significance (Xiao, 2010). Various PCR-based techniques employing specific primer pairs for the selective amplification of different genetic loci followed by sequencing had been used to characterize and classify Cryptosporidium species or genotypes (Quintero-Betancourt et al, 2002;Xiao et al, 2004). Some key markers included ribosomal RNA genes and spacers, the Cryptosporidium oocyst wall protein (cowp), the 70 kDa heat shock protein (hsp70), the thrombospondin-related adhesive protein (trap) genes and the 60 kDa glycoprotein (gp60) gene (Jex et al, 2008).…”

Giardia spp. e Cryptosporidium spp. em água de manancial superficial de abastecimento contaminada por dejetos humano e animal

“…e Cryptosporidium spp. pela dificuldade de distinção de organismos espécie-específicos (Ramirez et al, 2004;Xiao et al, 2004).…”