Analysis of results in surveillance of cholera in Hunan in 2006

Objective The study was conducted for the purpose of detecting cholera cases and water and food contaminated with Vibrio cholerae in a timely manner and taking early prevention and control measures to prevent the spread of the epidemic. Methods Comprehensive surveillance, combining conventional surveillance for diarrhea patients, external environment and food, and special one for snapping turtles potentially contaminated with Vibrio cholerae, was conducted. Results A total of 89 661 cases of detected Vibrio cholerae were found from 111 526 registered diarrhea patients in Hunan province, 2006, resulting in a detection rate of 80.39%. There were four positive patients, all infected with Vibrio cholerae O139. Findings from 44 533 environmental and food samples revealed 35 113 water environmental samples that were all negative, and 5377 fishery products, of which 16 samples were found positive, the positive rate being 0.30%; positive samples included snapping turtles and bullfrogs, whereas the other 4043 were negative. In the special surveillance for snapping turtles, 33 positive cases were detected from 2323 samples, the positive rate being 1.42%. The cholera toxin gene test found 20 toxigenic strains from the 34 detected strains, accounting for 58.80%; sensitivity test was conducted for 28 strains, and 100% sensitivity was found to norfloxacin, ciprofloxacin and amikacin, as well as 92.86% sensitivity to doxycycline and co-trimoxazole. Conclusion Aquatic products such as snapping turtles and bullfrogs constituted the major causes of cholera in Hunan. Therefore, strengthened surveillance and health management for aquatic products is needed.