Environmental Vibrio cholerae non O1/ non O139 from the Gangetic delta: a diarrhoeal disease purview

Abstract

Diarrhoea still remains an unsolved enigma in developing countries, a major concern for the health planners. We targeted the abundance and toxicity of Vibrio cholerae non-O1/non-O139 (NOVC) in Gangetic riverine-estuarine ecosystem. A total of 74 V. cholerae were isolated from 120 water samples (68 NOVC, 6 V. cholerae O1) from two sampling sites off river Ganges. V. cholerae showed distinct seasonality, with steady increase from summer to monsoon, steep ascent in post-monsoon and an abrupt decline in winter. Highest number of NOVC was isolated form Howrah, attributed to low salinity and high anthropogenic influence. Environmental NOVC harboured hlyA (94.0 %), rtxA (81.0 %) and toxR (28.0 %) genes. About 23.4 % of the hlyA harbouring NOVC showed haemolytic activity. Accessory toxin genes (tlcR, toxT, RJ and LJ and aldA), among 3–5 % of the NOVC carry significant health implications. Haemolytic activity and biofilm formation in NOVC, during unfavourable conditions, facilitates gene transfer and emphasises the role of environmental NOVC in diarrhoeal incidence in South Bengal, India.

Keywords:

• V. cholerae
• environment
• toxin gene
• biofilm