Microbiological indicators of water quality in the Xochimilco canals, Mexico City

Juárez-Figueroa, Luis; Silva-Sánchez, Jesús; Uribe-Salas, Felipe; Cifuentes-García, Enrique

doi:10.1590/s0036-36342003000500009

Cited by 20 publications

(11 citation statements)

References 9 publications

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“…Also, while G. lamblia positively correlated with rainfall (r = 0.91; a = 0.1), the case was opposite for C. parvum (r = -0.98; a = 0.05). Results confirm the role of solar radiation in the attenuation of some target pathogens (Davies-Colley et al 2000) and the influence of rainfall on waste or pathogen inputs into the canals via run-offs (Melnick et al 1977;Juarez-Figueroa et al 2003) or dilution (Diallo et al 2009) of some pathogens.…”

Section: Quantification Of Pathogens and Statistical Analysessupporting

confidence: 63%

Molecular Techniques in Ecohealth Research Toolkit: Facilitating Estimation of Aggregate Gastroenteritis Burden in an Irrigated Periurban Landscape

et al. 2011

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Assessment of microbial hazards associated with certain environmental matrices, livelihood strategies, and food handling practices are constrained by time-consuming conventional microbiological techniques that lead to health risk assessments of narrow geographic or time scope, often targeting very few pathogens. Health risk assessment based on one or few indicator organisms underestimates true disease burden due a number of coexisting causative pathogens. Here, we employed molecular techniques in a survey of Cryptosporidium parvum, Giardia lamblia, Campylobacter jejuni, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., Shigella spp., Vibrio cholera, and Rotavirus A densities in canal water with respect to seasonality and spatial distribution of point-nonpoint pollution sources. Three irrigational canals stretching across nearly a 150-km(2) periurban landscape, traditionally used for agricultural irrigation but function as vital part of municipal wastewater stabilization in recent years, were investigated. Compiled stochastic data (pathogen concentration, susceptible populations) and literature-obtained deterministic data (pathogen dose-response model parameter values) were used in estimating waterborne gastroenteritis burden. Exposure scenarios include swimming or fishing, consuming canal water-irrigated vegetables, and ingesting or inhaling water aerosols while working in canal water-irrigated fields. Estimated annual gastroenteritis burden due individual pathogens among the sampling points was -10.6log(10) to -2.2log(10) DALYs. Aggregated annual gastroenteritis burden due all the target pathogens per sampling point was -3.1log(10) to -1.9log(10) DALYs, far exceeding WHO acceptable limit of -6.0log(10) DALYs. The present approach will facilitate the comprehensive collection of surface water microbiological baseline data and setting of benchmarks for interventions aimed at reducing microbial hazards in similar landscapes worldwide.

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Section: Quantification Of Pathogens and Statistical Analysessupporting

confidence: 63%

Molecular Techniques in Ecohealth Research Toolkit: Facilitating Estimation of Aggregate Gastroenteritis Burden in an Irrigated Periurban Landscape

et al. 2011

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“…Along with pharmaceuticals, certain bacterial species, part of which are pathogenic or resistant to antibiotic agents or both, are released into wastewater irrigation channels and fields (e.g., [20], [21], [22]). Bacteria resistant to antibiotics have been isolated previously from wastewater-irrigated fields in India [23].…”

Section: Introductionmentioning

confidence: 99%

Accumulation of Pharmaceuticals, Enterococcus, and Resistance Genes in Soils Irrigated with Wastewater for Zero to 100 Years in Central Mexico

et al. 2012

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Irrigation with wastewater releases pharmaceuticals, pathogenic bacteria, and resistance genes, but little is known about the accumulation of these contaminants in the environment when wastewater is applied for decades. We sampled a chronosequence of soils that were variously irrigated with wastewater from zero up to 100 years in the Mezquital Valley, Mexico, and investigated the accumulation of ciprofloxacin, enrofloxacin, sulfamethoxazole, trimethoprim, clarithromycin, carbamazepine, bezafibrate, naproxen, diclofenac, as well as the occurrence of Enterococcus spp., and sul and qnr resistance genes. Total concentrations of ciprofloxacin, sulfamethoxazole, and carbamazepine increased with irrigation duration reaching 95% of their upper limit of 1.4 µg/kg (ciprofloxacin), 4.3 µg/kg (sulfamethoxazole), and 5.4 µg/kg (carbamazepine) in soils irrigated for 19–28 years. Accumulation was soil-type-specific, with largest accumulation rates in Leptosols and no time-trend in Vertisols. Acidic pharmaceuticals (diclofenac, naproxen, bezafibrate) were not retained and thus did not accumulate in soils. We did not detect qnrA genes, but qnrS and qnrB genes were found in two of the irrigated soils. Relative concentrations of sul1 genes in irrigated soils were two orders of magnitude larger (3.15×10−3±0.22×10−3 copies/16S rDNA) than in non-irrigated soils (4.35×10−5±1.00×10−5 copies/16S rDNA), while those of sul2 exceeded the ones in non-irrigated soils still by a factor of 22 (6.61×10–4±0.59×10−4 versus 2.99×10−5±0.26×10−5 copies/16S rDNA). Absolute numbers of sul genes continued to increase with prolonging irrigation together with Enterococcus spp. 23S rDNA and total 16S rDNA contents. Increasing total concentrations of antibiotics in soil are not accompanied by increasing relative abundances of resistance genes. Nevertheless, wastewater irrigation enlarges the absolute concentration of resistance genes in soils due to a long-term increase in total microbial biomass.

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“…Large numbers of Enterobacteriaceae, including a wide range of Salmonella serotypes, were found in the city canals in Jakarta (25). In a Thai study, Campylobacter was detected in the canals of the Bangkok Metropolitan Area (22), whereas Giardia cysts were found in Mexico City canals (32). However, in these parts of the world, city canals serve different purposes than canals in cities in developed countries, such as washing, drinking, and cooking, and are subject to other contamination sources, like the disposal of raw waste by the part of the population that is not connected to the sewer systems.…”

Section: Discussionmentioning

confidence: 99%

Monitoring of Waterborne Pathogens in Surface Waters in Amsterdam, The Netherlands, and the Potential Health Risk Associated with Exposure to Cryptosporidium and Giardia in These Waters

Schets

Wijnen

Schijven

et al. 2008

Appl Environ Microbiol

114

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Microbiological indicators of water quality in the Xochimilco canals, Mexico City

Cited by 20 publications

References 9 publications

Molecular Techniques in Ecohealth Research Toolkit: Facilitating Estimation of Aggregate Gastroenteritis Burden in an Irrigated Periurban Landscape

Molecular Techniques in Ecohealth Research Toolkit: Facilitating Estimation of Aggregate Gastroenteritis Burden in an Irrigated Periurban Landscape

Accumulation of Pharmaceuticals, Enterococcus, and Resistance Genes in Soils Irrigated with Wastewater for Zero to 100 Years in Central Mexico

Monitoring of Waterborne Pathogens in Surface Waters in Amsterdam, The Netherlands, and the Potential Health Risk Associated with Exposure to Cryptosporidium and Giardia in These Waters

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