Epidemiological characteristics of scrub typhus and genotyping of the pathogen Orientia tsutsugamushi in Chuxiong prefecture, Yunnan province, China

doi:10.11853/j.issn.1003.8280.2020.03.008

Abstract

Abstract: Objective To investigate the epidemiological characteristics of scrub typhus in Chuxiong Yi autonomous prefecture (Chuxiong prefecture), Yunnan province, China, and to analyze the genotypes of the pathogen Orientia tsutsugamushi (Ot). Methods The data of scrub typhus cases were collected for epidemiological analysis. Blood samples from the patients were obtained to detect the nucleic acids of Ot by PCR and sequence the Tsa56 gene. Homology and phylogenetic analyses were performed using bioinformatics software. Results A total of 2 507 cases of scrub typhus were reported in Chuxiong prefecture from 2015 to 2018, with a mean annual incidence of 22.79/100 000. Scrub typhus occurred in all 10 counties/cities of the prefecture, and 96.01% (2 407/2 507) of the total cases were distributed in Chuxiong, Dayao, Yongren, Nanhua, and Shuangbai counties/cities. The cases occurring during July to October accounted for 88.35% (2 215/2 507) of the total number. The male-to-female ratio was 1:1.34. The majority of the patients were aged from 30 to 69 years (78.42%, 1 966/2 507), and most cases were farmers (84.92%, 2 129/2 507). PCR detected 4 samples (CX1601, CX1602, CX1603, and CX1604) positive for Ot nucleic acids from 6 blood samples of scrub typhus patients. The Tsa56 gene was obtained for sequencing, and the homology and phylogenetic analyses showed that CX1601 and CX1604 shared high homology and close genetic relationship with the Kato strains of Ot, while CX1602 and CX1603 were highly homologous and closely related to Gilliam strains, but relatively low homology and large genetic distances with other strains. Conclusion Scrub typhus in Chuxiong prefecture belongs to Kato or Gilliam type. In recent years, there was a high incidence and an increasing trend year by year. It is necessary to strengthen the surveillance and control of the host and vector.

Key words: Scrub typhus, Epidemiological characteristics, Orientia tsutsugamushi, Genotype

摘要： 目的调查云南省楚雄彝族自治州（楚雄州）恙虫病流行特征及其恙虫病东方体（Ot）的基因型。方法收集恙虫病病例资料并进行流行病学分析。采集恙虫病患者血液标本，用PCR法检测Ot核酸并测定Tsa56基因序列，用相关生物信息学软件进行同源性和系统进化分析。结果 2015-2018年楚雄州共报告恙虫病病例2 507例，年平均发病率为22.79/10万。该州所辖10个县（市）均有恙虫病病例报告，其中楚雄、大姚、永仁、南华和双柏县（市）发病数占全州发病总数的96.01%（2 407/2 507）。7-10月发病数占全年发病总数的88.35%（2 215/2 507）。病例男女性别比为1：1.34，30~69岁年龄组发病居多（1 966/2 507，78.42%），职业分布以农民为主（2 129/2 507，84.92%）。经PCR检测，从6份恙虫病患者血液标本中检测到Ot核酸阳性4份（CX1601、CX1602、CX1603和CX1604），将获得的Tsa56基因进行测序，同源性和系统进化分析表明，CX1601和CX1604与Ot中的Kato型菌株具有较高的同源性和较近的亲缘关系，CX1602和CX1603则与Gilliam型菌株具有较高的同源性和较近的亲缘关系，而与其他型菌株同源性较低，亲缘关系较远。结论楚雄州恙虫病病原体属于Kato型或Gilliam型，近几年高发并有逐年上升趋势，应加强恙虫病宿主及媒介的监测和防控工作。

关键词: 恙虫病, 流行特征, 恙虫病东方体, 基因型

CLC Number:

R376⁺.2

HU Ting-song, LI Ying, HU Qiu-ling, WU Xue-lin, GAO Li-fen, LI Guo-wei, WANG Zhi-yong, HU Hai-mei, WANG Yi-yin, ZHANG Hai-lin, ZHANG Fu-qiang. Epidemiological characteristics of scrub typhus and genotyping of the pathogen Orientia tsutsugamushi in Chuxiong prefecture, Yunnan province, China[J]. Chines Journal of Vector Biology and Control, 2020, 31(3): 282-288.

胡挺松, 李应, 胡秋凌, 吴学林, 高丽芬, 李国伟, 王志勇, 胡海梅, 王意银, 张海林, 张富强. 云南省楚雄州恙虫病流行特征及其病原体东方体基因分型研究[J]. 中国媒介生物学及控制杂志, 2020, 31(3): 282-288.

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