Li N.,East China University of Science and Technology |
Li N.,Centers for Disease Control and Prevention |
Xiao L.,Centers for Disease Control and Prevention |
Elwin K.,UK Cryptosporidium Reference Unit |
And 14 more authors.
Emerging Infectious Diseases | Year: 2014
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.
Robinson G.,UK Cryptosporidium Reference Unit |
Wright S.,Creative Science Company Science 310263 |
Elwin K.,UK Cryptosporidium Reference Unit |
Hadfield S.J.,UK Cryptosporidium Reference Unit |
And 6 more authors.
International Journal for Parasitology | Year: 2010
To provide re-description of Cryptosporidium cuniculus Inman and Takeuchi, 1979 (synonymous with rabbit genotype), a species closely related to Cryptosporidium hominis, the morphology, natural and experimental host specificity, and genetic characterisation were investigated. The morphology and diagnostic characteristics are typical of other intestinal species of Cryptosporidium, albeit with slightly larger oocysts (5.55-6.40 × 5.02-5.92 μm; mean 5.98 × 5.38 μm; length:width = 1.1; n= 50). Natural hosts appear to be European rabbits (Oryctolagus cuniculus) and humans (Homo sapiens). Experimental infections have been established in weanling rabbits (O. cuniculus), immunosuppressed Mongolian gerbils (Meriones unguiculatus) and immunosuppressed adult Porton strain mice (Mus musculus), but not in neonatal mice. Patterns of infection measured by oocyst shedding are significantly different compared with C. hominis, particularly in rabbits. Histological examination reveals endogenous stages in the brush border of the epithelium of the small intestinal villi, but clinical signs are absent. Inoculation of human HCT-8 cells results in discrete clusters of endogenous stages. A close relationship with C. hominis is inferred from molecular analyses at the ssrRNA, 70. kDa heat shock protein (HSP70), actin, Cryptosporidium oocyst wall protein (COWP), 60. kDa glycoprotein (GP60) genes and a region encoding a product of unknown function (LIB13). Sequences contained limited, consistent polymorphisms at the ssrRNA, HSP70 and actin genes, were identical at the COWP and LIB13 genes and demonstrated two unique families at the GP60 gene. Although genetically closely related, there are significant biological differences between C. cuniculus and C. hominis that support these protozoa being separate species. This is based on the current understanding of these organisms and relies on the assumption that mating between these species would not normally occur. If this is subsequently demonstrated their categorisation may need to be re-addressed. © 2010 Australian Society for Parasitology Inc.
Pollock K.G.J.,Health Protection Scotland |
Ternent H.E.,University of Glasgow |
Mellor D.J.,University of Glasgow |
Chalmers R.M.,UK Cryptosporidium Reference Unit |
And 3 more authors.
Zoonoses and Public Health | Year: 2010
The spatial and temporal epidemiology of human cryptosporidiosis was described by analysing sporadic cases reported in Scotland from 2005 to 2007. Measures of livestock density and human population density were explored as indicators of the geographical variation in prevalence. Cryptosporidium parvum was more common in areas with lower human population densities, with a higher ratio of the number of farms to human inhabitants and with a higher ratio of the number of private water supplies to human inhabitants. Cryptosporidium parvum caused disease in humans in rural areas and in areas with high ruminant livestock density, whereas Cryptosporidium hominis was more common in the more densely human populated areas of Scotland. The association of private water supplies and increased Cryptosporidium reports merits further public health efforts. © 2009 Blackwell Verlag GmbH.
Briggs A.D.M.,Public Health England |
Briggs A.D.M.,University of Oxford |
Boxall N.S.,Public Health England |
Van Santen D.,Public Health England |
And 3 more authors.
Epidemiology and Infection | Year: 2014
Water supply-associated cryptosporidiosis outbreaks have decreased in England since the application of risk reduction measures to public water supplies. We hypothesized that smaller outbreaks were occurring which could be better detected by enhanced surveillance. Rolling analysis of detailed questionnaire data was applied prospectively in a population of 2.2 million in the south of England in 2009 and 2010. Detection of spatiotemporal clusters using SaTScan was later undertaken retrospectively. Together these approaches identified eight outbreaks, compared to an expectation of less than one based on national surveillance data. These outbreaks were small and associated with swimming pool use or, less commonly, direct (e.g. petting-farm) contact with animals. These findings suggest that frequent small-scale transmission in swimming pools is an important contributor to disease burden. Identification of swimming pool-level risk factors may inform preventative measures. These findings and the approaches described may be applicable to many other populations and to some other diseases. Copyright © Cambridge University Press 2014.
PubMed | UK Cryptosporidium Reference Unit
Type: Journal Article | Journal: Journal of clinical microbiology | Year: 2011
Real-time PCR has the potential to streamline detection and identification of Cryptosporidium spp. in human clinical samples. In the present article, we report the first such assay to allow not only detection and differentiation of the most common human pathogens, Cryptosporidium hominis and Cryptosporidium parvum, but also simultaneous amplification of a region of the small subunit (SSU) rRNA gene, permitting direct sequence analysis to identify any Cryptosporidium species. An internal control is incorporated to identify the presence of PCR inhibitors. Analytical sensitivity was determined to be as low as 200 oocysts per gram of feces processed, equivalent to 2 oocysts per PCR. The C. hominis and C. parvum PCRs specifically detected only species/genotypes in their respective target clades. Diagnostic sensitivity and specificity, evaluated against a widely used conventional nested SSU rRNA gene PCR as a nominated gold standard using a panel of 258 (151 positive and 107 negative) samples, were 100% and 99.1%, respectively. The assay agreed with PCR-restriction fragment length polymorphism analysis of the Cryptosporidium oocyst wall protein gene for 134 of 136 (98.5%) samples tested prospectively and typed two additional isolates. The real-time PCR assay was sensitive, specific, and reproducible and significantly improved laboratory work flow and turnaround times.