Epidemiological and laboratory investigations of outbreaks of diarrhoea inrural South India: implications for control of disease

Two epidemics of acute, watery diarrhoea in villages in North Arcot distric t, India, were investigated. The attack rates were 10.03 and 15.53 per 100 population, the median duration was 5 days and enteric pathogens were prese nt in 56.8 % and 60.3 % of specimens from the two villages, but no predomin ant pathogen was identified. Examination of stools from a 20 % age-stratifi ed random sample of the population of one of the villages after the epidemi c found 22.9 % of asymptomatic subjects excreted bacterial enteric pathogen s. Despite the high background of enteric pathogen carriage, the isolation rates for shigellae, enteropathogenic Escherichia coli and Shiga-toxin prod ucing E. coli were significantly higher (P < 0.001, P < 0.02, P < 0.05) dur ing the epidemic. The epidemics may have been caused by faecal contaminatio n of well water following rain. Point-of-use techniques for water disinfect ion may be most effective for preventing such outbreaks, but further resear ch into the development of appropriate technology is required.