Survey on a typhoid outbreak caused by contaminated water in rural area in Jiangxi province

On 28 September 2010, 26 suspected typhoid cases were reported in a village in Jiangxi province. The survey was conducted to identify its cause and mode of transmission and provide evidence to control the outbreak. The case definition was made. The cases were searched by household interview after checking medical records in local health care facility. The survey on drinking water was conducted to understand the category of drinking water, villagers drinking volume, relative risk of different drinking water and dose response relation of drinking unboiled water. The serological detection of IgM antibody to Salmonella typhi was conducted with Tubex assay. Totally 40 cases were found in the village, including 25 suspected cases and 15 confirmed cases; 39 cases (98%) were in group Chenkeng of the village. The attack rate in group Chenkeng (34%) was significantly higher than that in other groups (0.34%) (RR=983, 95%CI:136-7096). In group Chenkeng, the attack rate in the villagers who drank water from Mountain Chenkeng (42%) was significantly higher than that in those who drank water from other source (4%,) (RR=11, 95%CI:2.1-160). The retrospective cohort study showed that among the villagers who drank water from Mountain Chenkeng, those who drank unboiled water had higher disease risk (RR=2.5, 95%CI:1.1-7.9). Among the villagers who drank unboiled water, the dose response relation with the disease was observed (2 test for trends: 5.7, P=0.016). Environmental survey indicated that the water from Mountain Chenkeng was contaminated. The total coliforms and fecal coliforms in 6 water samples taken at the source water exceeded the limit for drinking water. The IgM antibody to Salmonella typhi was detected in 15 confirmed cases with Tubex assay. The cause of the typhoid outbreak was identified as drinking unboiled, contaminated water from Mountain Chenkeng. It is suggested that the government should take measures to protect the water source in rural area to prevent the incidence of waterborne diseases.