Alarming Situation of Spreading Enteric Viruses Through Sewage Water in Dhaka City: Molecular Epidemiological Evidences

Abstract

Global burden of acute viral gastroenteritis remains high, particularly in developing countries including Bangladesh. Sewage water (SW) is an important node to monitor enteric pathogens both in the environment and among the population. Analysis of SW in Dhaka city deems crucially important because a large number of urban-city dwellers live in Dhaka city, the capital of Bangladesh, under a constant threat of precarious sewerage system. In this study, we collected raw SW from five locations of Dhaka city every month from June 2016 to May 2017. It was concentrated with polyethylene glycol (PEG) and investigated for three major enteric viruses, rotavirus A (RVA), norovirus GII (NoV GII) and adenovirus (AdV) using polymerase chain reaction (PCR). Most of these SW samples collected from both hospitals and non-hospital areas yielded enteric viruses: 76% samples were positive for AdV, followed by 53% NoV GII and 38% RVA. Viral load was determined as much as 1 × 10⁷ copies/ml for RVA and 3.5 × 10³ copies/ml for NoV GII. Importantly, NoV GII and AdV that can affect people of all ages were predominated during monsoon also when SW overflows and spreads over a wide and crowded area. Genotypes G1, G2, G3, G8, and G9 for RVA, GII.4 for NoV, and type 41 for AdV were detected representing the current profile of circulating genotypes in the population. This study provides the first evidence of distribution of major diarrheal viruses in SW in Dhaka city which is alarming showing grave risk of impending outbreaks through exposure.

Keywords: Adenovirus; Dhaka; Norovirus GII; Rotavirus A; Sewage.