Identifying the primary sources of fecal contamination along the beaches and rivers of Trinidad

Mitochondrial DNA marker: A PCR approach for tracking rat (Rattus rattus and Rattus norvegicus) fecal pollution in surface water systems

Rats act as reservoirs for a wide range of zoonotic pathogens and can negatively impact human health. In this study, we developed a novel dye base mitochondrial DNA (mtDNA) PCR-assay (RatMt) specifically targeting a 180 bp fragment of the NADH dehydrogenase subunit 2 gene for detecting fecal pollution from two species of rats (Rattus rattus and Rattus norvegicus) in environmental samples. Estimation of Escherichia coli concentrations in Rattus norvegicus fecal pellets suggested that there were approximately 2.24 × 10 4 ± 4.86 × 103 MPN/g of fecal pellet. The RatMt PCR assay was robust, had a detection limit of rat feces in water of 0.274 ± 0.14 mg/100 mL and was 100 % specific for detecting Rattus rattus and Rattus norvegicus fecal mtDNA. Fecal Indicator Bacteria (FIB) along an urbanized gradient in Pensacola-Bay was assessed by the IDEXX Colilert™ - 18 and indicated that the majority of the fifteen sampling sites in the Pensacola-Bay area had E. coli concentrations >410 MPN/100 mL. Rattus rattus and Rattus norvegicus mtDNA were detected in all the urban marine sites, three of the urban freshwater sampling areas, and three of the forested sampling sites. The RatMt PCR assay is a useful tool for rapidly detecting Rattus rattus and Rattus norvegicus fecal pollution in environmental samples.

Tracking the sources of Leptospira and nutrient flows in two urban watersheds of Puerto Rico

This study investigated the relationship between nutrient levels, source of fecal contamination, and pathogenic Leptospira in Puerto Rico's northern coast and San Juan Bay Estuary (SJBE) aquatic ecosystems. Microbial source tracking (MST) was also used to investigate the connections between sources of feces contamination and the presence of Leptospira. Eighty-seven water samples were collected during the June (n=44) and August (n=43) in 2020. To quantify phosphorus and nitrogen concentrations, standard USEPA protocols were utilized, specifically Methods 365.4 for total and dissolved phosphorus, 351.2 for total Kjeldahl nitrogen and ammonium, and 353.2 for nitrate. Lipl32 gene-specific quantitative polymerase chain reaction (qPCR) was used to detect the presence of Leptospira. Human (HF183), canine (BacCan-UCD), and equine (HoF597) MST assays were utilized to trace the origins of fecal contamination. Forty one percent of the locations exceeded Puerto Rico's authorized total phosphorus limit of 160 g L-1, while 34% exceeded the total nitrogen limit of 1700 g L-1. Nearly half of the streams examined are affected by eutrophication. The MST analysis identified human and canine feces as the most prevalent contaminants, affecting approximately 50% of the sites. In addition, Leptospira was detected in 32% of the June samples. There was a significant correlation (r = 0.79) between the incidence of pathogenic Leptospira and the human bacterial marker (HF183). This study illuminates the central role of anthropogenic inputs in nutrient enrichment and pathogen proliferation in Puerto Rico's aquatic ecosystems.

Environmental risk assessment for fecal contamination sources in urban and peri-urban estuaries, in Escambia and Santa Rosa counties, FL, USA

Fecal pollution of estuaries and adjacent creeks and streams is of significant concern along the Gulf of Mexico. The prospective threat to human life and water quality impairment via fecal pollution is a substantial danger to the strength and resistance of coastline areas. Pensacola, FL, has a prosperous coastal tourism industry that is utilized for numerous other uses, such as recreational watersports and boating, seafood, and shellfish harvesting. However, the frequency and severity of fecal contamination present possible socio-economic issues, specifically financial hardships. Therefore, understanding the source, abundance, and fate of fecal microbial pollutants in aquatic systems signifies an imperative initial stage for detecting the host sources and techniques to lessen their transport from the landscape. This research aimed to quantify the fecal indicator bacteria (FIB), Escherichia coli, and perform microbiological fecal source tracking to verify if the fecal inputs are of either animal or human host origin. Surface water samples were taken from urban and peri-urban creeks for two sampling periods (February 2021 and January 2022), and IDEXX Colilert-18 (USEPA Standard Method 9223) was used for E. coli enumeration. DNA extractions were obtained from each sample, and quantitative PCR was utilized for fecal microbial source tracking (MST) to detect human, dog, ruminant, and bird host-specific Bacteroides DNA. The result indicates elevated quantities of FIB, E. coli, that surpass the threshold considered safe regarding human health. E. coli at six sites over the two sampling periods exceeded the impairment threshold, reaching as high as 866.4 MPN/100 ml. Fecal source tracking identified human host fecal contamination at four of nine sites, dogs at three of nine, and birds at one site. However, those sites with sources identified via MST all had E. coli levels below impairment thresholds. No sites were determined to be positive for ruminant as a source or for the pathogen Helicobacter pylori. No canine host fecal inputs were found in January 2022, and only one site with human sewage. Our results highlight the utility of MST in assessing bacterial inputs to water bodies and the challenges.