CREH Analytical Ltd

Leeds, United Kingdom

CREH Analytical Ltd

Leeds, United Kingdom
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Chalmers R.M.,Singleton Hospital | Robinson G.,Singleton Hospital | Elwin K.,Singleton Hospital | Hadfield S.J.,Singleton Hospital | And 3 more authors.
Journal of Water and Health | Year: 2010

As part of investigations into the cause of a waterborne outbreak of Cryptosporidium hominis infection linked to a mains water supply, surface waters and wastewater treatment plants were tested for Cryptosporidium spp. Oocyst counts in base flow surface water samples ranged from nil to 29 per 10l. Oocyst counts in effluent from a community wastewater treatment plant were up to 63 fold higher and breakout from one septic tank five logs higher. There were no peak (storm) flow events during the investigation. C. hominis, four named genotypes (cervine, muskrat II, rat, W19) and six new small subunit ribosomal RNA gene sequences were identified. Four of the new sequences were closely related to Cryptosporidium muskrat genotype I, one was closely related to the fox genotype and one to Cryptosporidium canis. C. hominis was found extensively in the catchment, but only at sites contaminated by wastewater, and in the treated water supply to the affected area. All were gp60 subtype IbA10G2, the outbreak subtype. Multiple routes of contamination of the reservoir were identified, resulting in persistent detection of low numbers of oocysts in the final water. This work demonstrates the utility of genotyping Cryptosporidium isolates in environmental samples during outbreak investigations. © IWA Publishing 2010.

Robinson G.,Singleton Hospital | Chalmers R.M.,Singleton Hospital | Stapleton C.,Aberystwyth University | Palmer S.R.,University of Cardiff | And 3 more authors.
Journal of Applied Microbiology | Year: 2011

Aims: Investigating the distribution and origin of Cryptosporidium species in a water catchment affected by destocking and restocking of livestock as a result of a foot and mouth disease epidemic. Methods and Results: Surface water, livestock and wildlife samples were screened for Cryptosporidium and oocysts characterised by sequencing SSU rRNA and COWP loci, and fragment analysis of ML1, ML2 and GP60 microsatellite loci. Oocyst concentrations in water samples (0-20.29 per 10l) were related to rainfall events, amount of rainfall and topography. There was no detectable impact from catchment restocking. Cryptosporidium spp. found in water were indicative of livestock (Cryptosporidium andersoni and Cryptosporidium parvum) and wildlife (novel genotypes) sources. However, C. andersoni was not found in any animals sampled. Calf infections were age related; C. parvum was significantly more common in younger animals (<4weeks old). Older calves shared Cryptosporidium bovis, Cryptosporidium ryanae and C. parvum. Wildlife shed C. parvum, Cryptosporidium ubiquitum, muskrat genotype II and deer genotype. Conclusions: Several factors affect the occurrence of Cryptosporidium within a catchment. In addition to farmed and wild animal hosts, topography and rainfall patterns are particularly important. Significance and Impact of the Study: These factors must be considered when undertaking risk-based water safety plans. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.

Fewtrell L.,Helmholtz Center Munich | Kay D.,Aberystwyth University | Watkins J.,CREH Analytical Ltd | Davies C.,CREH Analytical Ltd | Francis C.,CREH Analytical Ltd
Journal of Flood Risk Management | Year: 2011

A quantitative microbial risk assessment of flooding and gastrointestinal illness was carried out using a combination of floodwater quality data from the existing literature on pathogen concentrations in the various floodwater components, the use of microcosms to determine pathogen die-off rates in floodwaters and opportunistic sampling of actual UK floodwaters. Two flood-related scenarios were examined in a hypothetical population to provide an assessment of the likely cases of gastrointestinal illness resulting from contact with floodwater. The results of the study suggest that significant numbers of people are at risk of illness (especially from viral gastroenteritis) during the clean-up process rather than during the inundation and withdrawal phases. Additional sampling during flood events of water and sediment would strengthen the empirical policy evidence base required for estimating the severity and range of health impacts using the risk assessment methodology developed in this paper. © 2011 The Authors. Journal of Flood Risk Management © 2011 The Chartered Institution of Water and Environmental Management.

Smith R.P.,Veterinary Laboratories Agency VLA | Chalmers R.M.,Singleton Hospital | Mueller-Doblies D.,Veterinary Laboratories Agency VLA | Clifton-Hadley F.A.,Veterinary Laboratories Agency VLA | And 5 more authors.
Preventive Veterinary Medicine | Year: 2010

The study investigates farms suspected of being sources of zoonotic human cryptosporidiosis. A variety of implicated farm animal species were sampled and tested to detect Cryptosporidium oocysts and investigate genetic linkage with human patients. Risk factor information was collected from each farm and analysed by multivariable logistic regression to detect significant associations between factors and Cryptosporidium in animals. The results showed that average sample prevalence of Cryptosporidium infection was highest in cattle, sheep and pigs (∼40-50%), in the mid-range in goats and horses (20-25%) and lowest in rabbits/guinea pigs, chickens and other birds (∼4-7%). A single sample from a farm dog was also positive. Cryptosporidium parvum, which has zoonotic potential, was the commonest species and was most likely to be present in cattle and, to a lesser extent, in sheep. In particular, young calves and lambs shed C. parvum and this finding was corroborated in a statistical model which demonstrated that samples from groups of preweaned animals were 11 times, and immature animal groups six times, more likely to be positive than groups of adult animals, and that samples from a farm with a cattle enterprise were twice as likely to be positive than farms without a cattle enterprise. On seven out of eight farms, at least one C. parvum isolate from an animal sample was indistinguishable at the gp60 locus from those found in the human patients, indicating that farm animals are a likely source of infection for humans. Crown Copyright © 2010.

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