Epidemiological investigation of enterohemorrhagic Escherichia coil O157:H7 infection status in Xuzhou City of Jiangsu Province from 1999 to 2006

Objective This study was to investigate the epidemic characteristics of enterohemorrhagic Escherichia coli (EHEC) O157:H7 infection in the City of Xuzhou, observe the O157:H7 carrying status in diarrhea patients and host animals and its relationship with disease onset, and provide a scientific basis for establishing prevention and control strategies. Methods The O157:H7 infection status and its epidemic characteristics were analyzed by using descriptive epidemiological approaches. Results A total of 131 cases of infectious diarrhea concomitant with renal failure (HUS) caused by O157:H7 were reported in Xuzhou in 1999 and 2006, with a fatality rate of 87.79%. Most of the cases were reported in Feng County and Tongshan County, which accounted for 74.81% of all the cases. The peak period of incidence occurred from June to September with 77.10% of all cases. 77.10% of the patients were old people over 60 years old, and the majority patients were farmers with the percentage of 91.60%. The ratio of male over female was 1∶1.34. The diarrhea patients and host animals were verified to be related to O157:H7 infection through continuous surveillance. The virulent gene of O157:H7 varied over different years. Conclusion The infection status of O157:H7 in Xuzhou were kept stable since the outbreaks in 1999 and 2000. It was found out that the epidemic of O157:H7 was associated with the bacteria carrier rate of diarrhea patients and host animals, the positive rate of virulent gene and the variance of the gene, although the epidemic reasons were complex and the transmitting mechanism remained unclear. O157:H7 carrier rate of diarrhea patients and host animals could be applied as a surveillance index in epidemic outbreak warning.