Tube Well Use as Protection Against Rotavirus Infection During the Monsoons in an Urban Setting

Abstract

Rotavirus, a diarrheal pathogen spread via fecal-oral transmission, is typically characterized by a winter incidence peak in most countries. Unlike for cholera and other waterborne infections, the role of sanitation and socioeconomic factors on the spatial variation of rotavirus seasonality remains unclear. In the current study, we analyzed their association with rotavirus seasonality, specifically the odds of monsoon cases, across 46 locations from 2001 to 2012 in Dhaka. Drinking water from tube wells, compared to other sources, has a clear protective effect against cases during the monsoon, when flooding and water contamination are more likely. This finding supports a significant environmental component of transmission.

Keywords: Dhaka; monsoon season; rotavirus; seasonality; tube wells; urban health.

Figure 1.

Rotavirus seasonality. A, Average annual fraction of rotavirus cases occurring during the monsoon season for each location, based on 16 years of data. (Red dot indicates location of the Dhaka Hospital.) B, Spatial clusters in rotavirus seasonality identified using the local Moran index (I) statistic. Asterisks represent locations with a significant local Moran I statistic (pseudo P < .05); colors represent the type of spatial classification. High-high indicates locations with a high fraction of cases during the monsoons that are surrounded by other locations with a high fraction; high-low, locations with a high fraction surrounded by locations with a low fraction; low-high, locations with a low fraction surrounded by locations with a high fraction; and low-low, locations with a low fraction surrounded by other locations with a low fraction. Map showing residence locations, within and outside Dhaka metropolitan area, for rotavirus patients at the Dhaka Hospital.

Figure 2.

A, B, Spatial distribution of cases in the individual-level survey data that occurred during the winter (A) and monsoon (B) seasons. C, Estimated fixed effects (and 95% confidence interval) for the full model (gray) and for the model with the lowest Akaike information criterion (AIC) (black). The estimated fixed effects represent the estimated association between each of the independent variables and the odds of a case occurring during the monsoons, holding all else fixed (including random effects). The red dashed line indicates an odds ratio (OR) of 1. Map showing residence locations, within and outside Dhaka metropolitan area, for rotavirus patients at the Dhaka Hospital.