Investigation of pathogenic Yersinia in dogs from plague foci of rodents in the resting period of plague in Yunnan

Abstract

Objective To investigate and analyze the distribution of pathogenic Yersinia in dogs, an indicator animal of plague foci in Yunnan province, in order to explore the microecological status of Yersinia pestis, and we provide more clues for the epidemic and resting of plague.

Methods Multiple stratified sampling method was used to select 10 plague source counties (historical epidemic area, recent epidemic area, reignition epidemic area and present epidemic area) with different epidemic intensity and different geographical locations that entered the epidemic resting period at different times as survey points in Yunnan province from July 2016 to August 2017. The dog anal swabs was collected and placed in the modified PBS. After 4 °C cold enrichment for 15 days, 1 mL of mixed medium was absorbed to extract DNA, and using polymerase chain reaction (PCR) to detect foxA, inv and caf1 genes, which gene positive using the selective agar medium for Yersinia to isolate the three kinds of pathogenic Yersinia. The isolated bacteria were analyzed by ail virulence genes detection.

Results A total of 915 samples of dog anal swabs were collected from 10 endemic counties in Yunnan province, 15 of which were positive for foxA gene (15/915, 1.64%), no positive inv gene and caf1 gene were detected. 12 strains of Yersenia enterocolitis (12/915,1.3%) were isolated, 2 of which had ail virulence gene. Yersinia pestis and Yersinia pseudotuberculosis were not isolated.

Conclusion Yersinia enterocolitis were found in dogs from plague foci of rodents in Yunnan province. No clue of plague bacteria was found, and the cause is worth further investigation.

Abstract

摘要： 目的 对云南省家鼠鼠疫疫源地鼠疫指示动物-犬中致病性耶尔森菌分布情况调查分析, 以探求鼠疫菌微 生态状况, 为研究鼠疫的流行与静息提供更多线索。 方法2016年7月一2017年8月采用多重分层抽样法在云南省抽 取不同时间进人流行静息期、不一样流行强度和不同地理位置的家鼠鼠疫疫源县共10个(历史疫区、近史流行区、复燃 疫区、现疫区)作为调查点, 采集犬肛门拭子置于改良PBS中, 经4°C冷增菌15 d后, 吸取混匀的培养液1 mL提取DNA, 采用PCR方法检测 foxA、inv及 caf1基因, 并对基因阳性材料采用耶尔森选择培养基分离菌株, 提取菌株的DNA并检测 其 aU毒力基因。 结果 云南省10个疫源县共采集犬肛门拭子标本915份, oxA基因检测阳性率为1.64%(15/915), 未 检出 n基因与 caf1基因阳性。小肠结肠炎耶尔森菌分离阳性率为1.3%(12/915), 其中2株具有 ai!毒力基因；未分离 到鼠疫耶尔森菌和假结核耶尔森菌。 结论 云南省家鼠鼠疫疫源地犬中存在小肠结肠炎耶尔森菌的分布；未发现鼠 疫菌线索, 其原因值得进一步探讨。