Current prevalence and sub-genotype analysis of Blastocystis in residents of Luoyang City

doi:10.12140/j.issn.1000-7423.2022.02.013

Abstract

Abstract:

Objective To understand the infection status and distribution of sub-genotype of Blastocystis hominis in Luoyang City, Henan Province. Methods From September 13-20, 2020, a cross-sectional study with cluster random sampling was conducted in Luoning County, which was selected from the Luoyang City soil-transmitted nematode surveillance sites as the survey site. In the study, we selected no less than 200 permanent residents aged 3 and above from five administrative villages of Cheng jia zhuang, Xijie, Zhong gao, Nanpo and Mogou. A questionnaire was performed to collect the basic information of name, gender, age, ethnicity, occupation, education level, village and whether they had taken deworming medication in the three months prior to the survey. For those infected with Blastocystis information on living hygiene conditions and clinical signs were investigated. Faecal DNA was extracted and the small subunit RNA (SSU-rRNA) gene was amplified by PCR, sequenced and BLAST in the GenBank database to identify the genetic subtype. A phylogenetic tree based on the SSU-rRNA gene was constructed using the Mega 7.0, and allstatistical analysis was performed using SPSS 25.0 software; Results A total of 890 people were investigated and 20 people were found positive for Blastocystis infection. The Blastocystis infection rate was 2.2% (20/890). Among them, the male infection rate was 2.0% (8/399), and the female infection rate was 2.4% (12/491), and the difference was not statistically significant(χ² = 0.193, P > 0.05). The 11-20 years age group had the highest infection rate, which was 5.1% (3/59), and the difference in infection rate among different age groups was statistically significant(Fisher =11.895, P < 0.05). Farmers had the highest infection rate at 2.6%, and there was no significant difference in infection rates among different occupations(Fisher = 1.535, P > 0.05). The infection rate among junior high school educated participants was the highest (2.7%), and there was no significant difference in infection rate among different education levels(Fisher = 1.283, P > 0.05). We found the Blastocystis infection rate in Zhonggao Village was the highest at 4.3% (7/164), and differences among 5 administrative villages were statistically significant (Fisher = 10.929, P < 0.05). As for PCR amplification, results showed that 20 samples amplified the SSU-rRNA gene fragment of Blastocystis, about 1 100 bp in size. Sequencing results showed that ST3 subtypes accounted for 90.0% (18/20), and ST1 subtypes accounted for 10.0% (2/20), which was consistent with the phylogenetic tree results. Within the infectious of Blastocystis, Mogou and Zhonggao villages included both ST3 subtypes and ST1 subtypes, and Nanpo and Xijie villages were both ST3 subtypes. Then, the phylogenetic tree results showed that 18 of the 20 positive faecal samples were in the same evolutionary branch as the Austrian isolate (GenBank accession no. MN914073.1), the German isolate (GenBank accession no. MK801403.1) and the Singaporean isolate (GenBank accession no. KX618192.1), all of which were ST3 subtypes. Two copies were in the same evolutionary branch as the German isolate (GenBank accession no. MK801408.1) and the Austrian isolate (GenBank accession no. MN914072.1), both ST1 subtypes of Blastocystis. As for hygienic conditions and clinical manifestations in 20 infected patients, 65.0% (13/20) used dry toilets or cesspools, 35.0% (7/20) used flushing toilets, and 45.0% (9/20) kept pets or livestock at home. 15.0% (3/20) showed symptoms of abdominal pain, diarrhea and abdominal distension, including one ST1 subtype and two ST3 subtypes; 20% (3/20) showed symptoms of dry stools, including one ST1 subtype and three ST3 subtypes. Conclusion The overall infection rate of B. hominis in the population of Luoyang City is relatively low, with the main sub-genotype ST3.

Key words: Blastocystis sp., Subtype, Epidemiological investigation, Luoyang City

CLC Number:

R531.9

CHEN Hui-hui, LI Yun-xia, NING Chao-qun, DENG Yan, ZHANG Hong-wei, WEI Xue-fang, SUO Hui-fang, ZHANG Ting, LIU Qin, CHEN Jun-hu, TIAN Li-guang. Current prevalence and sub-genotype analysis of Blastocystis in residents of Luoyang City[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2022, 40(2): 216-222.

Figures/Tables 3

Table 1

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组别 Group	调查人数 No. surveyed	感染人数 No. positive	感染率/% Infection rate/%	χ²/Fisher值 χ²/Fisher value	P值 P value
性别Gender
男Male	399	8	2.0	0.193	> 0.05
女Femal	491	12	2.4
年龄组/岁Age group/year
3~10	183	1	0.5	11.895	< 0.05
11~20	59	3	5.1
21~30	64	2	3.1
31~40	121	1	0.8
41~50	93	1	1.1
51~60	162	2	1.2
≥ 61	208	10	4.8
职业Occupation
农民Peasant	653	17	2.6	1.535	> 0.05
学生Student	163	3	1.8
学龄前儿童Preschooler	74	0	0
文化程度Education level
文盲或半文盲Illiterate or semi-literate	104	1	1.0	1.283	> 0.05
小学Primary	261	6	2.3
初中Junior	452	12	2.7
高中Senior	67	1	1.5
中专及以上Technical secondary and above	6	0	0
行政村Village
中高村Zhonggao Village	164	7	4.3	10.929	< 0.05
南坡村Nanpo Village	200	8	4.0
磨沟村Mogou Village	195	3	1.5
西街村Xijie Village	166	2	1.2
程家庄Chengjiazhuang Village	165	0	0