我国西南城市地区人芽囊原虫的流行病学特征

目的 了解我国城市地区人芽囊原虫的流行病学特征和基因型分布,为人芽囊原虫的防治提供科学参考依据。方法 在云南省昆明市4家哨点医院收集腹泻病例粪便样本1 121份,非腹泻人群粪便样本319份,使用结构化问卷收集研究对象基本信息,提取粪便基因组并采用PCR方法进行检查,对可疑阳性PCR产物进行测序,通过序列比对进行确诊,并通过进化树构建进行基因分型。结果 人芽囊原虫在全年龄组腹泻病例中检出率为4.2%;在女性腹泻人群中的检出率高于男性腹泻人群中的检出率(5.5%,2.9%;P=0.027,OR=1.98,95%CI=1.07-3.67);在不同年龄组腹泻人群中,人芽囊原虫的检出率没有差异(χ²=3.933,P=0.950);但具有明显季节分布特征(χ²=11.8,P<0.05);人芽囊原虫的检出率在城区、农村以及城乡结合部的腹泻人群中没有差异(χ²=2.427,P=0.297)。在腹泻人群和非腹泻人群中,人芽囊原虫I型基因型都占绝对优势。结论 人芽囊原虫依旧是西南城市地区感染人群的常见肠道寄生虫之一,感染主要以I型基因型为主,其致病性和基因型分布需持续研究和探索。

Epidemiological characteristics of Blastocystis hominis in urban region,southwestern China

We investigated the epidemiological characteristics and the genotype distribution of Blastocystis hominis in urban region of southwest China, and the study may provide scientific references for the prevention and treatment of Blastocystis hominis. A total of 1 121 diarrhea patients and 319 healthy controls were selected from four sentinel hospitals in Kunming of southwest China from June 2014 to July 2015. The stool specimens were collected to detect the Blastocystis hominis with PCR. A structured questionnaire was applied to each diarrhea case and healthy control after stool samples collection for their clinical manifestation (e.g. vomiting, fever and dehydration), demographic data (age, sex and residence) and types of the stool samples (watery, mucoid, or bloody and other forms); the phylogenetic trees were constructed using the neighbor-joining method with 1 000 bootstrap replicates; reference strains were downloaded from the GenBank. Results showed that the detection rate of Blastocystis hominis was 4.2% in diarrhea cases; the prevalence of Blastocystis hominis in female was higher than that of in male (5.5%, 2.9%, P=0.027, OR=1.98, 95%CI=1.07-3.67); no significant difference was found among diarrhea cases with different age groups infected with Blastocystis hominis (χ²=3.933, P=0.950); however, there was remarkable seasonal trend for Blastocystis hominis (χ²=11.8, P<0.05); the difference in detection rate of Blastocystis hominis among diarrheacases from rural-urban fringe zone, urban and rural area was not significant difference (χ²=2.427, P=0.297), the Blastocystis hominis subtype I was absolute dominant strain in diarrhea cases and healthy controls. In conclusion, Blastocystis hominis was still common intestinal parasites in urban population, Blastocystis hominis subtype I was the most prevalence in this region, the pathogenicity and subtype distribution of Blastocystis hominis need to be continuously studied.