Abstract：
BACKGROUND: The Junggar Basin plague focus was the most recently identified natural plague focus in China. Through extensive field investigations, great gerbils (Rhombomys opimus) have been confirmed as the main host in this focus, and the community structure of their parasitic fleas is associated with the intensity of plague epizootics. The aim of this study is to provide an indicator that can be surveyed to evaluate the risk of plague epizootics.
METHODS: Between 2005 and 2016, rodents and fleas were collected in the Junggar Basin plague focus. The parasitic fleas on great gerbils were harvested, and anti-F1 antibody in the serum or heart infusion of great gerbils was detected through indirect hemagglutination assay. Yersinia pestis (Y. pestis) was isolated from the liver and spleen of great gerbils and their parasitic fleas using Luria-Bertani plates. Receiver-operating characteristic (ROC) curve was used to evaluate the predictive value of flea index.
RESULTS: Between 2005 and 2016, 98 investigations were performed, and 6778 great gerbils and 68,498 fleas were collected. Twenty-seven rodents were positive for Y. pestis isolation with a positivity rate of 0.4%; 674 rodents were positive for anti-F1 antibody with a positivity rate of 9.9%. Among these 98 investigations, plague epizootics were confirmed in 13 instances by Y. pestis-positive rodents and in 59 instances by anti-F1 antibody-positive rodents. We observed a higher flea index among rodents with confirmed plague epizootic compared to the negative ones (P = 0.001, 0.002), with an AUC value of 0.659 (95% CI: 0.524-0.835, P = 0.038) for Y. pestis-positive rodents and an AUC value of 0.718 (95% CI: 0.687-0.784, P < 0.001) for anti-F1 antibody-positive rodents.
CONCLUSIONS: Significantly higher flea index was associated with confirmed plague epizootic cases among great gerbils and could be used to predict plague epizootics in this focus.
METHODS: Between 2005 and 2016, rodents and fleas were collected in the Junggar Basin plague focus. The parasitic fleas on great gerbils were harvested, and anti-F1 antibody in the serum or heart infusion of great gerbils was detected through indirect hemagglutination assay. Yersinia pestis (Y. pestis) was isolated from the liver and spleen of great gerbils and their parasitic fleas using Luria-Bertani plates. Receiver-operating characteristic (ROC) curve was used to evaluate the predictive value of flea index.
RESULTS: Between 2005 and 2016, 98 investigations were performed, and 6778 great gerbils and 68,498 fleas were collected. Twenty-seven rodents were positive for Y. pestis isolation with a positivity rate of 0.4%; 674 rodents were positive for anti-F1 antibody with a positivity rate of 9.9%. Among these 98 investigations, plague epizootics were confirmed in 13 instances by Y. pestis-positive rodents and in 59 instances by anti-F1 antibody-positive rodents. We observed a higher flea index among rodents with confirmed plague epizootic compared to the negative ones (P = 0.001, 0.002), with an AUC value of 0.659 (95% CI: 0.524-0.835, P = 0.038) for Y. pestis-positive rodents and an AUC value of 0.718 (95% CI: 0.687-0.784, P < 0.001) for anti-F1 antibody-positive rodents.
CONCLUSIONS: Significantly higher flea index was associated with confirmed plague epizootic cases among great gerbils and could be used to predict plague epizootics in this focus.
摘要：
背景：准噶尔盆地鼠疫是中国最近确定的自然鼠疫重点。通过广泛的实地调查，大沙鼠（Rhombomysopimus）已被确认为该焦点的主要宿主，它们的寄生跳蚤的群落结构与鼠疫流行病的强度有关。这项研究的目的是提供一个可以调查的指标，以评估鼠疫流行病的风险。
方法：在2005年至2016年之间，在准噶尔盆地鼠疫重点收集了啮齿动物和跳蚤。收获了大沙鼠身上的寄生跳蚤，通过间接血凝法检测大沙鼠血清或心脏输液中的抗F1抗体。鼠疫耶尔森氏菌（Y.鼠疫菌）使用Luria-Bertani平板从大沙鼠及其寄生跳蚤的肝脏和脾脏中分离出来。采用受试者工作特征(ROC)曲线评价跳蚤指数的预测价值。
结果：在2005年至2016年之间，进行了98项调查，收集了6778只沙鼠和68,498只跳蚤。27只鼠疫杆菌分离阳性，阳性率为0.4％；674只啮齿动物抗F1抗体阳性，阳性率为9.9％。在这98项调查中，鼠疫杆菌阳性啮齿动物在13例病例中确认了鼠疫流行病，抗F1抗体阳性啮齿动物在59例病例中确认了鼠疫流行病。与阴性鼠疫动物相比，我们观察到鼠疫动物的跳蚤指数更高（P=0.001，0.002），鼠疫杆菌阳性啮齿动物的AUC值为0.659（95％CI：0.524-0.835，P=0.038），抗F1抗体阳性啮齿动物的AUC值为0.718（95％CI：0.687-0.784，P<0.001）。
结论：跳蚤指数显著升高与大沙鼠中确认的鼠疫流行病病例相关，可用于预测该重点的鼠疫流行病。
方法：在2005年至2016年之间，在准噶尔盆地鼠疫重点收集了啮齿动物和跳蚤。收获了大沙鼠身上的寄生跳蚤，通过间接血凝法检测大沙鼠血清或心脏输液中的抗F1抗体。鼠疫耶尔森氏菌（Y.鼠疫菌）使用Luria-Bertani平板从大沙鼠及其寄生跳蚤的肝脏和脾脏中分离出来。采用受试者工作特征(ROC)曲线评价跳蚤指数的预测价值。
结果：在2005年至2016年之间，进行了98项调查，收集了6778只沙鼠和68,498只跳蚤。27只鼠疫杆菌分离阳性，阳性率为0.4％；674只啮齿动物抗F1抗体阳性，阳性率为9.9％。在这98项调查中，鼠疫杆菌阳性啮齿动物在13例病例中确认了鼠疫流行病，抗F1抗体阳性啮齿动物在59例病例中确认了鼠疫流行病。与阴性鼠疫动物相比，我们观察到鼠疫动物的跳蚤指数更高（P=0.001，0.002），鼠疫杆菌阳性啮齿动物的AUC值为0.659（95％CI：0.524-0.835，P=0.038），抗F1抗体阳性啮齿动物的AUC值为0.718（95％CI：0.687-0.784，P<0.001）。
结论：跳蚤指数显著升高与大沙鼠中确认的鼠疫流行病病例相关，可用于预测该重点的鼠疫流行病。
