关键词: 鼠疫自然疫源地, 静息, 内在保存, 致病性耶尔森菌, 交叉免疫

Abstract: Objective Through intensive surveillance of three years in a row, Yersinia pestis was found within the focus, which highly supports the inner preservation theory of plague. Methods From 2013 to 2015 in four plague foci where the outbreak took place, Xingyi county in Guizhou province, Xilin and Longlin counties in Guangxi Zhuang Autonomous Region and Luoping county in Yunnan province, samples of rodents were examined for Y. pestis, serum detection of rodent hosts and indicator animals were tested for F1 antibody; samples of rodents, dogs and pigs were isolated for Y. enterocolitica and Y. pseudotuberculosis. Pig and dog samples from plague free area in Guangxi and Guizhou provinces were also examined for Y. enterocolitica and Y. pseudotuberculosis. Diarrhea children ≤5 years old were surveyed for these two enteropathogens in plague free area of Guangxi. Results Rodents and indicator animals were found carrying the F1 antibody in natural plague foci during rest period. The isolation rate of Y. enterocolitica in animals of natural plague foci was 0.80%, 1.55% and 3.59% for rodents, dogs and pigs, the rate in plague free region was 3.86% and 12.71% for dogs and pigs. For pathogenic strains, it was 0.39% and 3.19% for dogs and pigs in natural plague foci, 1.19% and 7.43% in plague free regions. Yersinia pseudotuberculosis was only isolated in plague free areas. The infection rate in children (≤5 years old) with diarrhea in plague free area of Guangxi was 0.64%. Conclusion Yersinia pestis can still be found in natural plague foci during test period, proven by F1 antibody positive rodents and indicator animals, which highly supports the inner preservation theory of plague. The isolation rate of pathogenic Y. enterocolitica was higher in plague free area than plague foci, which is an evidence of cross immunity theory.

Key words: Natural plague focus, Rest periods, Inner preservation theory of plague, Pathogenic Yersinia, Cross immunity