Epidemiological investigation of an outbreak of acute diarrhoeal disease using geographic information systems

Abstract

An outbreak of acute diarrhoeal disease in a village in southern India was investigated through personal interviews of all households. Maps were drawn using geographic information system (GIS) tools of the water supply system, sewage channels and areas with observed faecal contamination of soil within and around the village. Geographic coordinates for each house in the village were extracted from a central database from the healthcare service provider for the village. Geographical clustering of cases was looked for using the SaTScan software, and diarrhoeal disease attack rates were calculated. Diarrhoeal disease occurred uniformly throughout the village without clustering in any area. All ages and both sexes were affected, but extremes of ages were at higher risk. Water samples collected for microbiological examination after instituting control measures showed high coliform counts. Chlorine levels in the water tested were found to be inadequate to decontaminate common pathogens. Local cultural practices such as indiscriminate defecation in public places, washing clothes and cleaning utensils from water taps where the community collected its drinking water, and poor engineering design and maintenance of the water supply system were the risk factors that could have contributed to this outbreak.

Drinking water and sanitation: household survey for knowledge and practice in rural area, Magudanchavadi, Salem district, India

“…31 Open air defecation, a common practice among villagers, may lead to contamination of the water supply system and result in outbreaks of diarrheal disease. 32,33 Open air defecation more common in our study than other rural area of Salem district. 31 Open air defecation close to human dwellings contributed to the conversion of large areas of land in and around the village into "defecation or faecal fields.…”

Point-of-Use Interventions to Decrease Contamination of Drinking Water: A Randomized, Controlled Pilot Study on Efficacy, Effectiveness, and Acceptability of Closed Containers, Moringa oleifera, and In-home Chlorination in Rural South India

“…[3][4][5][6] Even when population-based methods of water purification, such as chlorination of tanks, are successful, practices in the home, such as dipping tumblers or cups into wide-mouthed containers to obtain water, can cause recontamination. 7 Studies have shown that in the absence of recontamination, counts of thermotolerant coliforms will decrease significantly over hours to days in stored water samples.…”

Spatial methods for infectious disease outbreak investigations: systematic literature review

“…Attempts to prevent future outbreaks included improvement of infrastructure [45,46], change of policy [29,32,47] and generation of risk maps [48]. Luquero and colleagues, for instance, used results of their analysis to recommend specific regions in which to focus preparedness activities to avoid future cholera outbreaks in Guinea-Bissau [49].…”

“…Several studies also highlighted the usefulness of maps in reports or Reports by continent presentations to communicate results to health officials [29,47], policymakers [49,50] and the public [38]. Sarkar and colleagues, for example, presented dot maps of cases of acute diarrhoeal disease in a village in southern India to the local community and health authorities [46]. Their maps visualised the proximity of cases to a contaminated water supply, and the presentation resulted in release of funds to improve sanitation in the area.…”