我国西北部分地区Q热分子流行病学调查

Molecular epidemiological studies on Coxiella burnetii from Northwestern China

目的了解西北部分地区人群及媒介蜱Q热感染情况。方法采用布旗法采集游离蜱,应用巢式PCR扩增蜱Q热贝氏柯克斯体;采用间接免疫荧光法对当地居民进行血清Q热抗体检测。结果共检测11个蜱种2 460只蜱标本,有8个蜱种239只贝氏柯克斯体DNA阳性,总阳性率为9.72%。不同蜱种间阳性率差异有统计学意义(2χ=16.69,P<0.01),其中以青海血蜱阳性率最高,为59.38%;四省区阳性率差异有统计学意义(2χ=13.28,P<0.01),以宁夏阳性率最高,为17.96%。共采集当地居民血清725份,抗体检测阳性51份,不同职业人群抗体阳性率差异有统计学意义(χ2=4.03,P<0.05),以牧民阳性率为最高。相关危险因素调查显示,饲养牛羊、饲养的牛羊有不明原因流产、给牛羊接生时未采取保护措施等因素与血清学阳性率有关,其中前两个因素为危险因素,而接生时采取保护措施为保护因素。结论我国西北地区蜱及当地居民存在Q热感染现象。

Objective To investigate Coxiella burnetii infection in ticks and local residents from Northwestern China.Methods Ticks were collected by dragging a cloth over vegetation.After species identification,DNA of Coxiella burnetii was isolated from ticks and detected by nested PCR targeting 23S rRNA of Coxiella burnetii.An indirect immunofluorescent assay（IFA） was carried out to test antibodies（IgG） against Coxiella burnetii.Results A total of 2 460 ticks were captured and 11 species were identified.Two hundred and thirty-nine ticks from 8 species tested positive,indicating an overall prevalence of Coxiella burnetii of 9.72%.Positivity differed significantly among tick species（χ2=16.59,P0.01）and in different provinces（χ2=13.28,P0.01）;positivity was greatest with Haemaphysalis qinghaiensis and in Qinghai Province.A total of 725 serum samples were tested,and 51 of these tested positive.Positivity differed significantly among different occupations（χ2=4.03,P0.05）.Livestock breeding,livestock with miscarriages due to an unknown cause,and methods used to protect livestock were significantly associated with positivity for Coxiella burnetii,with OR of 5.13,6.05,and 0.39,respectively.Livestock breeding and livestock with miscarriages were both risk factors while methods of protection were a protective factor.Conclusion Infection with Coxiella burnetii is present in local residents and ticks from Northwestern China.