Study of water supply & sanitation practices in India using geographic information systems: some design & other considerations in a village setting.

BACKGROUND & OBJECTIVE: Availability of clean water and adequate sanitation facilities are of prime importance for limiting diarrhoeal diseases. We examined the water and sanitation facilities of a village in southern India using geographic information system (GIS) tools. METHODS: Places of residence, water storage and distribution, sewage and places where people in the village defaecated were mapped and drinking water sources were tested for microbial contamination in Nelvoy village, Vellore district, Tamil Nadu. RESULTS: Water in the village was found to be microbiologically unfit for consumption. Analysis using direct observations supplemented by GIS maps revealed poor planning, poor engineering design and lack of policing of the water distribution system causing possible contamination of drinking water from sewage at multiple sites. INTERPRETATION & CONCLUSION: Until appropriate engineering designs for water supply and sewage disposal to suit individual village needs are made available, point-of-use water disinfection methods could serve as an interim solution.

Water handling, sanitation and defecation practices in rural southern India: a knowledge, attitudes and practices study.

Diarrhoea and water-borne diseases are leading causes of mortality in developing countries. To understand the socio-cultural factors impacting on water safety, we documented knowledge, attitudes and practices of water handling and usage, sanitation and defecation in rural Tamilnadu, India, using questionnaires and focus group discussions, in a village divided into an upper caste Main village and a lower caste Harijan colony. Our survey showed that all households stored drinking water in wide-mouthed containers. The quantity of water supplied was less in the Harijan colony, than in the Main village (P<0.001). Residents did not associate unsafe water with diarrhoea, attributing it to 'heat', spicy food, ingesting hair, mud or mosquitoes. Among 97 households interviewed, 30 (30.9%) had toilets but only 25 (83.3%) used them. Seventy-two (74.2%) of respondents defecated in fields, and there was no stigma associated with this traditional practice. Hand washing with soap after defecation and before meals was common only in children under 15 years (86.4%). After adjusting for other factors, perception of quantity of water received (P<0.001), stated causation of diarrhoea (P=0.02) and low socio-economic status (P<0.001) were significantly different between the Main village and the Harijan colony. Traditional practices may pose a significant challenge to programmes aimed at toilet usage and better sanitation.

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

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.

Molecular and spatial epidemiology of cryptosporidiosis in children in a semiurban community in South India.

Cryptosporidium spp. are a leading cause of diarrhea in Indian children, but there are no data for prevalent species or subgenotypes. Genetic characterization of Cryptosporidium spp. by PCR-restriction fragment length polymorphism and spatial analysis of cases using Geographical Information Systems technology was carried out for 53 children with cryptosporidial diarrhea in an urban slum. The two most common species were C. hominis (81%) and C. parvum (12%). Other species identified were C. felis and C. parvum (mouse genotype). Five subgenotypes were identified at the Cpgp40/15 locus. Subgenotype Ia predominated among C. hominis isolates, and all C. parvum isolates were subgenotype Ic. C. hominis infection was associated with a greater severity of diarrhea. Sequencing of the Cpgp40/15 alleles of C. felis and C. parvum (mouse genotype) revealed similarities to subgenotype IIa and C. meleagridis, respectively. Space-time analysis revealed two clusters of infection due to C. hominis Ia, with a peak in February 2005. This is the first study to demonstrate space-time clustering of a single subgenotype of C. hominis in a setting where cryptosporidiosis is endemic. Molecular characterization and spatial analysis have the potential to further the understanding of disease and transmission in the community.

Geographic information systems and genotyping in identification of rotavirus G12 infections in residents of an urban slum with subsequent detection in hospitalized children: emergence of G12 genotype in South India.

Rotavirus infections by G12 strains in several countries have recently been described. In this study, we report the emergence of G12 strains in south India. Fourteen cases of G12 infection were identified between June and September 2005. G12 was seen in combination with P[6], P[8], or nontypeable P type. Nine cases, including five symptomatic infections and four asymptomatic infections, were identified as part of routine surveillance for rotavirus infections in a birth cohort in the community between June and July 2005. Significant temporal and time-space clustering of eight of these cases represents a possible recent introduction of a new rotavirus VP7 genotype. Previous rotavirus infections had been documented for six of the nine children in the community. In the following 2 months, five cases of G12 infection were identified among children presenting to a referral hospital with diarrhea. This is the first description of symptomatic and asymptomatic G12 infections in children in the community. The detection of G12 strains from different parts of the world in recent years suggests the possibility of its emergence as an important global genotype. Monitoring of cocirculating rotavirus strains and detection of emerging strains is important in the context of the availability of rotavirus vaccines.

Geographical information system (GIS) in investigation of an outbreak.

An outbreak of fever in a village in southern India was reported on 1st September, 2001. The first reported case presented with epistaxis and a platelet count of 27000h(1)/mm3. Clinical, laboratory and entomological evidence supported a diagnosis of dengue fever. One third of the village was affected and 3.7 % of the population presented with haemorrhagic symptoms; none were fatal. Five acute cases tested for dengue specific IgM showed that two were positive. The larvae of Aedes aegypti were discovered from domestic water collections in the village. Spatial analysis done with the help of Geographical Information Systems software (GIS) demonstrated a centrifugal spread of cases from the most affected street until it involved the entire village. Spatial analysis revealed that cases occurred in clusters and that these could not have occurred by chance. This was our first experience in producing a geo-referenced map of a village area and in spatial analysis. GIS is a novel and simple tool for outbreak investigations and the spatial analyst adds additional information to the data collected. Control of adult mosquitoes and larvae prevented the outbreak from spreading to an adjacent village.