Norovirus and human adenovirus occurrence and diversity in recreational water in a karst aquifer in the Yucatan Peninsula, Mexico.

AIMS: To determine the seasonal occurrence and diversity of norovirus (NoV) and human adenovirus (HAdV) in groundwater from sinkholes, and brackish water used for recreational activities in the karst aquifer of the Yucatan Peninsula, Mexico. METHODS AND RESULTS: Hollow fibre ultrafiltration was used to concentrate viruses and standard plaque assay methods were used to enumerate somatic and F+ specific coliphages as viral indicators. Real-time quantitative polymerase chain reaction assays were used to estimate the number of genome copies for NoV strains GI, and GII, and HAdVs. The predominant NoV genotypes and HAdV serotypes were identified by comparative sequence analysis. Somatic and male F+ specific coliphages were detected at concentrations up to 94 and 60 plaque-forming units per 100 ml respectively. The NoV genogroup I (GI) was associated with 50% of the sampled sites during the rainy season only, at concentrations ranging from 120 to 1600 genome copies per litre (GC l-1 ). The NoV genogroup II (GII) was detected in 30 and 40% of the sampled sites during the rainy and dry seasons, respectively, at concentrations ranging from 10 to 290 GC l-1 . During the rainy and dry seasons, HAdVs were detected in 20% of the sites, at concentrations ranging from 24 to 690 GC l-1 . Identification of viral types revealed the presence of NoV GI.2, GII.Pe, GII.P16 and GII.P17, and HAdV F serotypes 40 and 41. CONCLUSIONS: These findings demonstrate that NoVs and HAdVs are prevalent as virus contaminants in the karst aquifer, representing potential health risks particularly during the rainy season, in one of the most important areas used for tourism in Mexico. SIGNIFICANCE AND IMPACT OF THE STUDY: This is one of the few studies conducted in karst aquifers that provide a foundational baseline of the distribution, concentrations and diversity of NoVs and HadVs in these particular environments.

Molecular characterization of sewage-borne pathogens and detection of sewage markers in an urban stream in Caracas, Venezuela.

Molecular characterization of two sewage-borne pathogens identified hepatitis A virus (HAV) subgenotype IA and Giardia duodenalis assemblages A and B as predominant genotypes circulating in an urban area of Venezuela. This study reveals epidemiological features of human pathogens of worldwide distribution and the efficacy of molecular methods for accurate assessment of sewage pollution.

Detection and characterization of waterborne gastroenteritis viruses in urban sewage and sewage-polluted river waters in Caracas, Venezuela.

The detection and molecular characterization of pathogenic human viruses in urban sewage have been used extensively to derive information on circulating viruses in given populations throughout the world. In this study, a similar approach was applied to provide an overview of the epidemiology of waterborne gastroenteritis viruses circulating in urban areas of Caracas, the capital city of Venezuela in South America. Dry season sampling was conducted in sewers and in a major river severely polluted with urban sewage discharges. Nested PCR was used for detection of human adenoviruses (HAds), while reverse transcription plus nested or seminested PCR was used for detection of enteroviruses (HuEVs), rotaviruses (HRVs), noroviruses (HuNoVs), and astroviruses (HAstVs). HRVs were fully characterized with genotype-specific primers for VP4 (genotype P), VP7 (genotype G), and the rotavirus nonstructural protein 4 (NSP4). HuNoVs and HAstVs were characterized by sequencing and phylogenetic analysis. The detection rates of all viruses were >or=50%, and all sampling events were positive for at least one of the pathogenic viruses studied. The predominant HRV types found were G1, P[8], P[4], and NSP4A and -B. Genogroup II of HuNoVs and HAstV type 8 were frequently detected in sewage and sewage-polluted river waters. This study reveals relevant epidemiological data on the distribution and persistence of human pathogenic viruses in sewage-polluted waters and addresses the potential health risks associated with transmission of these viruses through water-related environmental routes.

Evaluation of enterococcal surface protein genes as markers of sewage contamination in tropical recreational waters.

A molecular monitoring strategy was developed to detect prevalence of two enterococcal surface protein genes (esp-1 gene and esp-2 gene) in isolates of enterococci from recreational waters in Hawaii as evidence of human sewage contamination. The sensitivity and specificity of the methods were evaluated in selected environmental samples including human sewage, ocean water samples near a sewage outfall, shoreline coastal beach waters, ambient soil samples and ambient streams not known to be contaminated with sewage. The results of this study show that the esp-1 and esp-2 genes are highly associated with enterococci from sewage sources as compared to non-point sources. Therefore these esp genes show promise as good indicators of sewage contamination. However, more sensitivity and specificity of esp genes are needed. Moreover, a more specific enumeration method for E. faecium and E. faecalis is needed so that subsequent test for the esp genes will be reliable and feasible.

Bacteroides spp. as reliable marker of sewage contamination in Hawaii's environmental waters using molecular techniques.

Standard PCR (SPCR) and quantitative PCR (QPCR) assays using primers for general and for human-specific Bacteroides 16S rRNA markers were selected as the molecular tests to assess sewage contamination in recreational waters of Hawaii and these same water samples were assayed for culturable concentrations of selected faecal microbial indicators. The results of this study showed that the general primer for Bacteroides was not useful because ambient and polluted water samples were positive for this marker. However, use of human-specific primers reliably detected sewage contamination. The human-specific Bacteroides detection data supported previously reported conclusions that concentrations of alternative faecal indicators (C. perfringens, FRNA coliphages) but not traditional faecal indicators (faecal coliform, E. coli, enterococci) are reliable indicators of faecal contamination in Hawaii's environmental waters. The QPCR assay for the human-specific Bacteroides 16S rRNA marker was faster, more sensitive and more reliable than comparable SPCR assay because OPCR assay provided additional information such as melting temperatures, which confirmed that the right amplicons were being measured and Ct values, which indicated the relative level of faecal contamination.

Microbiological assessment of ambient waters and proposed water sources for restoration of a Florida wetland.

This study evaluated the microbial quality of reclaimed and storm water as proposed sources for restoration of a Florida wetland. Bacterial indicators, bacteriophages and waterborne pathogenic microorganisms (Cryptosporidium, Giardia and infectious enteric viruses) were analysed during a 1-year period in order to determine potential public health risks associated with exposure to the proposed water sources for restoration. Ambient waters within the wetland (four active water wells and four major lakes) were included in the study in order to determine the microbial water quality before restoration. Storm water and lakes had the highest level of microbial contamination. Much lower levels of microbial indicators and waterborne pathogens were found in reclaimed water and groundwater. Pathogen occurrence in groundwater was intermittent. Owing to the small percentage of source waters (3.3%) migrating to the water wells, ambient concentration of microbial constituents in surface and groundwater could dominate microbial risk. The results of this study indicate that, in the light of the uncertainties involved in computing average Cryptosporidium concentrations, additional characterization of the current ambient water quality should be ongoing prior to restoration.

Impacts of Hurricanes Katrina and Rita on the microbial landscape of the New Orleans area.

Floodwaters in New Orleans from Hurricanes Katrina and Rita were observed to contain high levels of fecal indicator bacteria and microbial pathogens, generating concern about long-term impacts of these floodwaters on the sediment and water quality of the New Orleans area and Lake Pontchartrain. We show here that fecal indicator microbe concentrations in offshore waters from Lake Pontchartrain returned to prehurricane concentrations within 2 months of the flooding induced by these hurricanes. Vibrio and Legionella species within the lake were more abundant in samples collected shortly after the floodwaters had receded compared with samples taken within the subsequent 3 months; no evidence of a long-term hurricane-induced algal bloom was observed. Giardia and Cryptosporidium were detected in canal waters. Elevated levels of fecal indicator bacteria observed in sediment could not be solely attributed to impacts from floodwaters, as both flooded and nonflooded areas exhibited elevated levels of fecal indicator bacteria. Evidence from measurements of Bifidobacterium and bacterial diversity analysis suggest that the fecal indicator bacteria observed in the sediment were from human fecal sources. Epidemiologic studies are highly recommended to evaluate the human health effects of the sediments deposited by the floodwaters.