10 results found
Blyth J, Hazell L, Templeton MR, 2021, Immunological detection of thymine dimers in indigenous genomic DNA from pre-disinfection drinking water as an ultraviolet disinfection dosimeter, Environmental Science: Water Research and Technology, Vol: 7, Pages: 2010-2020, ISSN: 2053-1400
Culture-based methods are the primary methods used for the routine detection and enumeration of bacteria and viruses in water samples. In the context of ultraviolet (UV) disinfection, they are also the basis for reactor validation in drinking water treatment systems. However, the majority of microorganisms in drinking water are not culturable. In UV disinfection, the DNA of both the culturable and non-culturable microbial populations will form pyrimidine dimers in response to UV photon absorbance. In this research an enzyme-linked immuno-sorbent assay (ELISA) was used to detect thymine dimers in the extractable genomic DNA (gDNA) from the total microbial population in pre-disinfection drinking water as a UV disinfection dosimeter. The method was first optimised using “naked” (extracted prior to UV exposure) and in vivo (extracted post UV exposure) Escherichia coli gDNA, and then tested using water samplesfrom UK drinking water treatment plants. Samples were exposed to up to 120 mJ/cm2 of monochromatic (254 nm) UV light using a collimated beam device and an ELISA was applied to the gDNA. This approach, once optimised, resulted in linear relationships between the assay response and UV dose. This shows that ELISA-based enumeration of thymine dimers in total extractable gDNA from a mixed species population has the potential to provide a direct, relatively quick, sampling-based means of monitoring the UV disinfection dose being delivered by operating UV disinfection systems in drinking water treatment plants, without the need to spike a biodosimeter into the water nor take reactors out of service. Molecular techniques 2 measuring dimer formation may also offer the UV disinfection industry a method of demonstrating dose delivery where the culturing of target organisms is problematic.
Hazell L, Allan F, Emery AM, et al., 2021, Ultraviolet disinfection of Schistosoma mansoni cercariae in water, PLOS Neglected Tropical Diseases, Vol: 15:7:e0009572, ISSN: 1935-2727
Blyth J, Templeton MR, Court S-J, et al., 2021, Assessment of indigenous surrogate microorganisms for UV disinfection dose verification, Water and Environment Journal, ISSN: 1747-6585
Braun L, Hazell L, Webb AJ, et al., 2020, Determining the viability of Schistosoma mansoni cercariae using fluorescence assays: an application for water treatment, PLOS Neglected Tropical Diseases, Vol: 14, ISSN: 1935-2727
Background:Schistosome cercariae are the human-infectious stage of the Schistosoma parasite. They are shed by snail intermediate hosts living in freshwater, and penetrate the skin of the human host to develop into schistosomes, resulting in schistosomiasis infection. Water treatment (e.g. filtration or chlorination) is one way of cutting disease transmission; it kills or removes cercariae to provide safe water for people to use for activities such as bathing or laundry as an alternative to infested lakes or rivers. At present, there is no standard method for assessing the effectiveness of water treatment processes on cercariae. Examining cercarial movement under a microscope is the most common method, yet it is subjective and time-consuming. Hence, there is a need to develop and verify accurate, high-throughput assays for quantifying cercarial viability.Method:We tested two fluorescence assays for their ability to accurately determine cercarial viability in water samples, using S. mansoni cercariae released from infected snails in the Schistosomiasis Collection at the Natural History Museum, London. These assays consist of dual stains, namely a vital and non-vital dye; fluorescein diacetate (FDA) and Hoechst, and FDA and Propidium Iodide. We also compared the results of the fluorescence assays to the viability determined by microscopy.Conclusion:Both fluorescence assays can detect the viability of cercariae to an accuracy of at least 92.2% ± 6.3%. Comparing the assays to microscopy, no statistically significant difference was found between the method’s viability results. However, the fluorescence assays are less subjective and less time-consuming than microscopy, and therefore present a promising method for quantifying the viability of schistosome cercariae in water samples.
Braun L, Hazell L, Templeton MR, 2019, Water treatment processes for preventing transmission of schistosomiasis, American Society of Tropical Medicine and Hygiene (ASTMH) Annual Meeting, National Harbor, Maryland, USA
Hazell L, Templeton MR, 2019, Ultraviolet disinfection of schistosome cercariae in water using UV-C LEDs, American Society of Tropical Medicine and Hygiene (ASTMH) Annual Meeting, National Harbor, Maryland, USA
Braun L, Hazell L, Templeton MR, 2019, Water treatment for preventing schistosomiasis transmission: the effectiveness of chlorine against schistosome cercariae, International Water Association (IWA) 20th International Symposium on Health Related Water Microbiology, Vienna, Austria
Hazell L, Braun L, Templeton MR, 2019, Ultraviolet sensitivity of WASH (water, sanitation, and hygiene) related helminths: a systematic review, PLOS Neglected Tropical Diseases, Vol: 13:e0007777
Braun L, Hazell L, Allan F, et al., 2018, Comparison of methods for evaluating the motility, infectivity and viability of schistosome cercariae in water, American Society of Tropical Medicine and Hygiene (ASTMH) 67th Annual Meeting, New Orleans, Louisiana, USA
Sule M, Braun L, Luo X, et al., 2018, Systematic Review of Water Treatment Methods and Knowledge, Attitude and Perceptions of Case Study Communities, 2nd Early Career WASH Conference – New Perspectives in WASH
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