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Background: On September 28, 2010, 26 suspected typhoid fever cases were reported in a rural village in Jiangxi Province.We investigated this outbreak to identify the mode of transmission, and recommend prevention and control measures.Methods: We defined a suspected case as onset of fever (≥38℃) for ≥3 days from August 1 to October 10 among the villagers, with ≥2 of the following: Persistent headache, diarrhea, abdominal pain, constipation, rose spots, hepatomegaly, splenomegaly or relative bradycardia.A confirmed case was a suspected case with identification of Salmonella typhi from blood or stool specimens by culture or IgM antibody positive using TUBEX test.We searched cases by reviewing medical records in clinics and house to house visiting.Results: We found 40 cases (25 suspected and 15 confirmed), 39 of which were from village Area C.Among residents of Area C, 42% of 90 who used soakaway water developed disease compared with 4% of 25 who did not (relative risk [RR]=11,95% confidence interval [CI] =2.1-160).Among the residents who used soakaway water, 54% of 65 who drank unboiled water developed disease compared to 21% of 14 who drank boiled or bottled water (RR=2.5, 95% CI=1.1-7.9).The attack rate increased from 36% to 80% in proportion to the amount of unboiled water drunk (P<0.02, x2 test for trend).Soakaway water came directly from a stream.Total and fecal coliforms in 6 water specimens from the water distribution intake pipes exceeded the safety criteria.Conclusions: This typhoid fever outbreak was caused by drinking unboiled, polluted soakaway mountain water.We suggested that the local government should chlorinate the water source and advise the villagers to drink boiled water.