郑州市1例内脏利什曼病病例流行病学调查

Epidemiological investigation on a visceral leishmaniasis case in Zhengzhou City of Henan Province

目的对河南省郑州市1例内脏利什曼病病例进行流行病学调查,以确定感染来源、明确传播链、评估传播风险。方法收集郑州市1例内脏利什曼病患者临床资料,显微镜下检查患者骨髓穿刺液涂片,并对患者居住村庄重点人群和村庄内所有犬只采用rk39内脏利什曼病快速诊断试剂进行血清抗体检查和PCR检测。在患者家附近悬挂诱蛉灯,同时人工捕捉白蛉,对捕捉到的雌性中华白蛉进行PCR检测。采用巢式PCR对患者、阳性犬只和阳性白蛉DNA扩增内转录间隔区1(ITS1)基因并进行序列比对,同时基于ITS1基因序列构建系统进化树。结果患者反复不规则发热、全血细胞减少、血红蛋白偏低,骨髓穿刺液涂片查见大量利什曼原虫无鞭毛体,确诊为内脏利什曼病。采用rk39快速诊断试剂及PCR法共筛查患者居住地疫点范围内324名居民,抗体检测及PCR结果均为阴性。采用上述两种方法筛查疫点内犬只201只,其中rk39诊断阳性率为21.39%、PCR阳性率为13.93%。在疫点捕捉2065只雌性中华白蛉进行利什曼原虫PCR检测,阳性率为0.82%。患者、阳性犬只和阳性白蛉ITS1基因序列与婴儿利什曼原虫序列同源性为100%,确定感染虫株为婴儿利什曼原虫。结论郑州市内脏利什曼病患者、犬只和白蛉中存在婴儿利什曼原虫感染,证实当地存在婴儿利什曼病完整传播链,且传播风险较高;需强化防控措施,防止利什曼病在当地传播。

Objective To perform an epidemiological investigation on a case with visceral leishmaniasis in Zhengzhou City,Henan Province,and to identify the source of infection,so as to illustrate the transmission chain and assess the risk of local leishmaniasis transmission.Methods The medical data were collected from a case with visceral leishmaniasis in Zhengzhou City,and the patient’s bone marrow smears were detected by microscopy.Serum anti-Leishmania antibody test and PCR assay were performed among high-risk residents and all dogs in the village where the patient lived.Sandflies were captured using light traps and artificial traps,and the captured female Phlebotomus chinensis was subjected to PCR assay.The internal transcribed spacer 1(ITS1)gene was amplified with a nested PCR assay using the genomic DNA extracted from visceral leishmaniasis patients,positive dogs and sandflies,and the sequences were aligned with those download from NCBI.In addition,a phylogenetic tree was created based on the ITS1 gene.Results The visceral leishmaniasis patient had recurrent irregular fever,reduced complete blood counts,low hemoglobin,and a large number of Leishmania amastigotes in bone marrow smears,and was therefore diagnosed as visceral leishmaniasis.Both rk39 rapid diagnostic test and PCR assay tested negative among 324 residents living neighboring the patient’s residence,while 21.39%(43/201)dogs were positive for rk39 rapid diagnostic test and 13.93%(28/201)positive for PCR assay.There were 17 female Ph.chinensis tested positive for Leishmania(0.82%)by PCR assay,and the ITS gene sequences from visceral leishmaniasis patients,positive dogs and sandflies shared a 100%homology with L.infantum.The Leishmania species was therefore characterized as L.infantum.Conclusions L.infantum infection occurs in visceral leishmaniasis patients,dogs and sandflies in Zhengzhou City,indicating a complete transmission chain and a high transmission risk of visceral leishmaniasis by L.infantum.Intensified control measures are required to prevent local transmission of leishmaniasis in Zhengzhou City.