Epidemiology of enteric fever in area with high incidence in Yunnan province

Objective To analyze the epidemiological characteristics of enteric fever in Hongta district of Yuxi municipality in Yunnan from 2005 to 2008 and discuss the epidemic pattern and related risk factors of enteric fever. Methods Descriptive epidemiological analysis was conducted on the data of enteric fever epidemic in Hongta during this period and the results were compared with those in other areas in Yunnan. Results The incidence of enteric fever in urban area in Hongta district was 374.59/lakh, which was significantly higher than that in rural area (96.51/lakh). The epidemic lasted for long time with two incidence peaks. The incidence and case proportion of children less than 15 years old were lower than those in Yuxi or in Yunnan. The proportions of the cases of farmers, preschoolers, elementary and secondary students were low, whereas the proportions of the cases of college students, workers and clerks were high. All laboratory confirmed cases in 2008 were S. paratyphoid A infections with the isolated strains in subtypes of three predominant groups by PFGE, which probably indicated that these strains belonged to closely related clones. Conclusion The epidemiological characteristics of enteric fever in Hongta district were different with surrounding areas in Yunnan. It is necessary to develop targeted intervention measures to prevent and control typhoid and paratyphoid based the epidemiological characteristics and risk factors.