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Occurrence and identification of enteric pathogens Campylobacter, Cryptosporidium and Giardia recovered from groundwater addressed for human supply and in animal feces surrounded of the reservoirs and health impact assessment

Abstract

Introduction: Biological contamination of groundwater for public supply of water is poses risks to human health. The sources of contamination may be domestic sewage, farm animal feces (livestock, for example) carried by surface runoff, inadequate disposal of solid waste in addition to the hydrological conformation itself, which may intensify various contamination routes. This aspect is concerns since public water supply are associated with outbreaks of diarrheal disease, which can reach a lot of people. The pathogenic protozoa Giardia and Cryptosporidium have been assuming relevance in water production due to the resistance to chlorine usually used in conventional water treatment plants, low infectious doses and the ability to survive in the environment, as well as the relevance of the role of these protozoa in disease outbreaks. The pathogenic bacterium Campylobacter, not very studied in water sources in our country, has been reported as an etiological agent of outbreaks of diseases including waterborne diseases. Brazilian legislation for drinkingwater requires the monitoring of Giardia cysts and Cryptosporidium oocysts at the water catchment points, not specifying differences whether superficial or groundwater, when the concentration of E. coli exceeds 103 CFU/100mL. It also establishes the obligation a systematic evaluation of water supply systems, from the perspective of health risks with the implementation of the Water Safety Plan (PSA). Objective: The objective of this study is to quantify (oo) Giardia and Cryptosporidium cysts and to detect/quantify Campylobacter in water samples from groundwater reservoirs addressed for public supply and in animal feces in the vicinity of reservoirs; to perform the molecular characterization of the recovered (oo) cysts and bacterial isolates and, to evaluate the risk of infection by these pathogens through water ingestion. Methods: Samples from two selected groundwater reservoirs will be selected in the southern region of the city of São Paulo for 12 months at a biweekly frequency, totalizing 48 samples. The collection and analysis of the concentration of pathogenic protozoa will be carried out according to EPA/1623.1/2012. The detection/quantification of Campylobacter will be performed according to ISO 19458/2006 and ISO 17995/2005. The quantification of E. coli will be performed by chromogenic assay using the Colilert kit (Iddex), according to Standards Methods (22nd ed. 2012), SM 9223. Molecular characterization of (oo) cysts and bacterial isolates will be carried out using quantitative PCR reaction (qPCR). The probability of infection will be estimated using the quantitative microbial risk assessment (QMRA), with the uncertainties and variabilities being treated by the Monte Carlo Method. Expected Results: The expected results are as follows: to obtain results on the presence and concentration of pathogens - Giardia, Cryptosporidium and Campylobacter - in samples of water supply from underground reservoirs intended for public supply; to obtain information on the distribution of these protozoa in groundwater reservoir waters in view of the scarcity of such data in our state and country; to obtain data in order to estimate the probability of infection by ingestion of these water sources; to implement Campylobacter detection/quantification methodology in water samples at MicroRes Laboratory of FSP/USP; to train technicians to carry out the pathogenic bacterial Campylobacter detection/quantification in water samples. (AU)

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