Environmental Drivers of the Seasonal Prevalence of Enteropathogenic Bacteria in the Gulf Ecosystem of Gujarat, India: Unravelling Its Diarrheal Enigma

Abstract

Recurrent episodes of water borne diarrheal outbreaks is the pressing public health crisis in the Gulf of Khambat (GoK), Gujarat and its adjoining area. We aimed to identify seasonality of environmental signatures associated with the dynamics of Gulf enteropathogens and related health implications. A yearlong sampling data has been generated from the five sites across the GoK of high anthropogenic burden and contrasting hydrological settings. Hydro-chemical characteristics of water samples and bacteriological indices were analysed on field and laboratory condition respectively and robust statistics was applied to assess their interrelationship and associated health risks. Annual variation of hydro-chemical indices viz. temperature 26.4oC–36.7oC, pH 7.51–8.44, salinity 28.3–36.7 mS/cm, turbidity 3.6–995 NTU and Dissolved Oxygen (DO) was recorded in the water samples. Extremely high turbidity (70.5-995) along with high salinity (28.3-34.8) is found to be the unique characteristic feature of Gulf water, which facilitates the abundance of various enteropathogenic bacterial species, specially the clinically important ones like V. cholerae, V. alginolyticus and E. coli. Surprisingly, an explosive annual preponderance of V. alginolyticus could be observed throughout all the study sites and existence of V. cholerae is restricted only in the high turbid water (>500NTU) of Gulf. Detection of E. coli is also a significant report from this high saline habitat, indicating faecal contamination. Seasonality of Vibrios and coliforms are highly influenced by precipitation rate and turbidity of water (p<0.05). DO level is found to be another crucial marker which regulates distribution of enteropathogens across the Gulf water as well as indicates the pollution level of Gulf attributed to environmental health risk. This is the first report of a longitudinal study of enteropathogenic load in GoK and its direct relationship with diarrheal incidence profile, which adds valuable knowledge for the formulation of ‘bio-environmental tool’ for effective water quality monitoring and disease prevention.