Prevalence and influence factors of Blastocystis infection in residents of Dong ethnic group in Southeast Guizhou Province

doi:10.12140/j.issn.1000-7423.2023.06.009

Abstract

Abstract:

Objective To investigate the prevalence and influence factors of Blastocystis in the Dong ethnic group in Guizhou Province in 2022. Methods A cross-sectional survey was conducted through questionnaire investigation in the residents of Mangling Village and Diqing Village in Liping County, Dong ethnic group region, southeast Guizhou Province in 2022. The survey collected general demographic information, hygienic habits, evidence of gastrointestinal symtoms. In addition, fecal samples were collected to extract Blastocystis DNA from which the SSU rRNA gene fragment was amplified by PCR. The positive ampicon was sequenced, and the results were aligned by BLAST in the GenBank database to determine the subgenotype of Blastocystis. The MEGA7.0 software was used to construct phylogenetic tree based on the Blastocystis SSU rRNA gene sequence by neighbor-joining method. Chi-square test and Fisher exact probability method were used to analyze the influencing factors of Blastocystis infection in the residents included in this study. Results A total of 329 village residents were surveyed, including 200 females (60.8%) and 129 males (39.2%), with an average age of 47.95 ± 20.39 years, of which 98.5% (324/329) were of Dong ethnic group, and 1.2% (4/329) were of Han ethnic group. PCR results showed that 16 fecal samples amplified Blastocystis SSU rRNA fragments with a size of about 1 100 bp. The overall Blastocystis infection rate was 4.9% (16/329). There was no significant difference in the infection rates in males (3.1%, 3/129) and females (6.0%, 12/200) (χ² = 1.425, P > 0.05). The infection rate was higher in the age group over 69 years old, 8.1% (3/37), and there was no significant difference in the infection rate among different age groups (χ² = 3.865, P > 0.05). The Blastocystis infected individuals were all farmers, and the infection rate was 6.1% (16/261), and there was no significant difference in the infection rate between different occupations (χ² = 3.157, P > 0.05). The infection rate was the highest in households with 6 or more people (12.7%, 7/55), and the difference in infection rate between different household sizes was statistically significant (Fisher = 13.957, P < 0.01). There were 4 genotypes (ST2, ST3, ST6, ST10) infecting the residents of Mangling Village and Diqing Village. Among them, sub-genotype 6 is the most common, accounting for 50.0% (8/16), followed by sub-genotype 3, accounting for 25.0% (4/16). BLAST comparison analysis showed that the similarity between the positive sequences of 16 Blastocystis and the reference sequences was more than 90%. The phylogenetic tree results also showed that each gene subtype clustered with its reference sequence, and the parentage was high. Univariate analysis showed that drinking water source, family size, daily stool frequency and stool traits have significant differences in Blastocystis infection (χ² = 8.778, 9.552, 7.384, 15.680; P < 0.05). The results of multivariate analysis showed that drinking unboiled water [OR = 18.347, 95% CI: (3.754, 89.673)] was a risk factor for Blastocystis infection in rural residents. Conclusion The overall infection rate of Blastocystis among Dong ethnic residents in southeast Guizhou Province is comparatively, with the main subgenotype ST6. Drinking unboiled water is the main risk factor for infection with Blastocystis in rural residents.

Key words: Blastocystis sp., Subtype, Infection rate, Influence factor, Minority

CLC Number:

R531.9

LI Lin, ZHU Aiya, CAI Yuchun, YU Chenghang, CHEN Muxin, TIAN Liguang. Prevalence and influence factors of Blastocystis infection in residents of Dong ethnic group in Southeast Guizhou Province[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2023, 41(6): 725-732.

Figures/Tables 3

Table 1

Single factor analysis of influencing factors of Blastocystis infection in Dong ethnic residents in Southeast Guizhou Province

影响因素 Variable	调查人数 No. Investigate	感染人数 No. infected	感染率/% Infection rate/%	χ²值 χ² value	P 值 P value
性别 Gender				1.425	> 0.05
男 Male	129	4	3.1
女 Female	200	12	6.0
年龄/岁 Age/Year				3.865	> 0.05
≤ 17	49	0	0
18~45	58	4	6.9
46~69	185	9	4.9
> 69	37	3	8.1
职业 Occupation				3.157	> 0.05
农民 Farmer	261	16	6.1
非农民 Non-farmer	68	0	0
受教育程度 Educational level				4.256	> 0.05
文盲 Illiteracy	52	3	5.8
小学 Primary school	202	7	3.5
初中及以上 Junior high school and above	75	6	8.0
家庭人口数 No. family				9.552	< 0.05
3人及以下 Three persons and below	52	2	3.9
4人 Four persons	136	3	2.2
5人 Five persons	86	4	4.7
6人及以上 Six persons and above	55	7	12.7
厕所类型 Toilet type				0.021^b	> 0.05
旱厕 Latrine	10	1	1/10
粪池 Stercorary	12	1	1/12
水冲厕 Flush toilet	307	14	4.6
饮用水来源 Source of drinking water				8.778	< 0.01
开水 Boiled water	180	3	1.7
非开水 Non-boiled water	149	13	8.7
是否饲养家畜/禽 Whether to keep livestock/poultry				0.008	> 0.05
是 Yes	275	12	4.4
否 No	54	4	7.4
接触家畜/禽的频率 Frequency of contact with livestock/poultry				3.883	> 0.05
每天接触 Daily	191	9	4.7
每周接触3~4次 Three-four times a week	23	2	8.7
每周接触1~2次 One-two times a week	31	3	9.7
不接触 Never	84	2	2.4
用餐前洗手 Wash hands before eating				3.831	> 0.05
偶尔 Occasionally	86	3	3.5
经常 Frequently	177	9	5.1
每次 Every time	66	4	6.1
使用手清洁剂 Use cleaner				23.647^a	> 0.05
从不 Never	17	1	1/17
偶尔 Occasionally	244	12	4.9
经常 Frequently	36	3	0.8
每次 Every time	32	0	0
近3个月是否有临床症状 Whether there have been clinical symptoms in the last 3 months				3.563	> 0.05
是 Yes	42	2	4.8
否 No	287	14	4.9
是否有食欲不振、呕吐 Loss of appetite, vomiting				0	> 0.05
是 Yes	32	2	6.3
否 No	297	14	4.7
每日排大便次数 Number of bowel movements per day				7.384^a	< 0.05
1~2次 One-two times	312	14	4.5
3~4次 Three-four times	12	0	0
2~3天一次 Once every two-three days	5	2	2/5
大便性状 Character of stool				15.68	< 0.01
软便 Soft stool	264	8	3.0
干结便 Dry stool	41	3	7.3
稀便 Loose stool	24	5	20.8

Table 1

Table 2

Fig. 1

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变量 Variable	赋值 Variable assignment	回归系数Coefficient	标准误 Standard error	Wald χ²	P值 P value	OR（95% CI）
职业 Occupation	非农民 = 0，农民 = 1 Non-farmer = 0，Farmer = 1	18.033	4 335.06	0	> 0.05	—
饮用水来源 Source of drinking water	开水 = 0，非开水 = 1 Boiled water = 0，Non-boiled water = 1	2.909	0.81	12.916	< 0.01	18.347（3.754，89.673）
近3个月是否有临床症状 Whether there have been clinical symptoms in the last 3 months	否 = 0，是 = 1 No = 0，Yes = 1	-1.358	0.811	2.800	> 0.05	0.257（0.052，1.262）
家庭人口数 No. family	3人及以下 = 0 Three persons and below = 0			6.765	> 0.05
	4人 = 1 Four persons = 1	-1.252	1.014	1.524	> 0.05	0.286（0.039，2.088）
	5人 = 2 Five persons = 2	0.038	0.940	0.020	> 0.05	1.038（0.165，6.548）
	6人及以上 = 3 Six persons and above = 3	1.014	0.979	1.071	> 0.05	2.758（0.404，18.791）
大便性状 Character of stool	软便 = 0 Soft stool = 0			8.224	< 0.05
	稀便 = 1 Loose stool = 1	2.083	0.810	6.614	< 0.01	8.028（1.641，39.269）
	干结便 = 2 Dry stool = 2	1.585	0.756	4.394	< 0.05	4.880（1.109，21.480）