我国西沙群岛吸血昆虫的种群动态和鼠形动物病原感染检测

Population dynamics of the blood-sucking insects and detection of pathogens in the rodents from Xisha Islands of China

目的研究我国西沙群岛吸血昆虫的种群动态以及鼠形动物病原感染情况,为当地传染病防控提供资料。方法2014年1月至7月在西沙群岛的永兴岛和石岛以灯诱法诱捕昆虫,每个月2次。结合形态和分子特征对昆虫进行种类鉴定并统计种群数量。用胶体金试剂条和PCR检测鼠形动物的常见病原感染情况,依据形态学初步鉴定鼠形动物体外寄生虫。结果西沙群岛的吸血昆虫中,库蚊、阿蚊和库蠓为优势种群,蠓在4月密度最高(55.55%,6 984/12 573),并在西沙群岛采集到贝氏司蛉(n=11)。鼠形动物血清中A型金黄色葡萄球菌肠毒素和A型肉毒毒素的阳性检出率分别为3.45%(1/29)和14.00%(7/50),鼠疫和立克次体病抗体均为阴性。巢氏PCR扩增70只鼠形动物的立克次体Sta58基因片段,阳性率为11.43%(8/70)。获得鼠形动物体外寄生虫共248个个体,其中革螨占93.55%(232/248)。结论吸血昆虫在西沙群岛未见明显的种群动态变化,本研究首次记述了西沙群岛的白蛉;鼠形动物中恙虫病立克次体和2种细菌的毒素携带率较高。

Objective To investigate the population dynamics of blood-sucking insects and detect the pathogen of rodents in Xisha Islands of China, so as to provide information for prevention and control of infectious diseases in the area. Methods From January to July in 2014, we collected blood-sucking insects in Yongxing and Shi Islands twice a month using light traps. The specimens were identified by morphologic characters and molecular markers. Meanwhile, the population size was calculated. The pathogenic infections of rodents were detected by immuno-colloidal gold chromatographic test strips and PCR assay. And the ectoparasites in the rodents were initially identified by morphologic characters. Results The dominant species of blood-sucking insects in Xisha Islands were species of Genus Culex, Arrnigeres and Culicoides, and in April the population density of biting midge was the highest （55. 55% , 6 984/12 573）. Phlebotomine sandfly specimen was also collected and identified as Sergentomyia baily （n= 11） by mtDNA-CO I sequences. The positive rates of Staphylococcus aureus enterotoxin type A and Botulinum toxin type A were 3. 45% （1/29） and 14. 00% （7/50） in the rodent serum samples, while all the samples were negative for Tsutsugamushi disease and Plague antibodies. Sta58 gene of Rickettsia tsutsugamushi was amplified by nested PCR in 70 rodent＇s spleen tissues, with the positive rate being 11.43% （8/70）. A total of 248 ectoparasites were collected, and 93.55 % （232/248） of them was gamasid mites. Conclusion The population dynamics of blood-sucking insects has no obvious change. Phlebotomine sandflies has been first recorded in Xisha Islands. The infection rates by Rickettsia tsutsugamushi and two bacterial toxins are high.