Analysis on endemic status of soil-transmitted nematode infection in China in 2019

doi:10.12140/j.issn.1000-7423.2021.05.015

Abstract

Abstract:

Objective To understand the endemic status and characteristics of soil-transmitted nematode infection in China in 2019 to provide data support for developing control strategies. Methods Survey was carried out in nationwide surveillance sites (counties) in 31 provinces/municipalities/autonomous regions in China in 2019. A unified sampling method was used in all surveillance sites: each site was divided into five areas geographically (east, west, south, north, and mid part), followed by selecting one administrative village from each area; 200 permanent residents older than 3 years were cluster sampled, resulting in 1 000 residents being surveyed in each surveillance site. Stool samples were collected from survey participants and examined microscopically using the modified Kato-Katz thick smear method (two slide-reading/sample) for parasite eggs, which were counted for estimating infection rate and infection intensity. Infection rates were analyzed using Chi-square test. In addition, soil surveys Ascaris eggs were conducted in 23 provinces/municipalities/autonomous regions, including Beijing, Fujian, and Gansu; one soil sample was collected from farmer’s field or vegetable garden from each of five households randomly selected from each village. From the soill samples, hook worm larvae were identified using 5% salt solution at 45 ℃, while Ascaris eggs were examined by floating method with sodium nitrate solution. A comparative analysis of the infection rates of overlapping surveillance sites in 2019 and 2018 was conducted. Results In total, 424 766 people from 414 nationwide surveillance sites were investigated in 2019, the overall infection rate of soil-transmitted nematodes was 1.40% (5 959/424 766), with the highest found in Sichuan (8.05%, 2 518/31 292), followed by Yunnan (5.30%, 885/16 693) and Chongqing (3.87%, 238/6 149). There was no significant difference between infection rate in males (1.37%, 2 842/207 188) and females(1.43%, 3 117/217 578) (χ ² = 2.84, P > 0.05). The participant group aged ≥ 60 years had the highest infection rate, of 2.51% (2 722/108 260), followed by the 45-59 age group (1.19%, 1 237/104 218) and the 7-14 age group (1.12%, 657/58 556), with statistically significant differences among the age groups (χ² = 1 351.00, P < 0.01). The infection rates of hookworm, Ascaris lumbricoides, and Trichuris trichiura were 0.84% (3 580/424 766), 0.36% (1 528/424 766) and 0.27% (1 126/424 766), respectively, with the majority were of light infection. In 2019, 2 056 soil samples were examined, and found the detection rate of Ascaris eggs and hookworm larvae was 5.79% (119/2 056) and 3.45% (71/2 056), respectively. In 2019, 77 surveillance sites in 25 provinces/municipalities/autonomous regions overlapped with the sites in 2018, where the infection rate was 1.43% in 2019, being compared with 1.42% in 2018, showing no statistically significant difference (χ² = 0.01, P > 0.05). Conclusion The overall infection rate of soil-transmitted nematodes in China in 2019 was at a low level, but provinces with higher infection rate and transmission risk remained, thus continuing surveillance and control are urged.

Key words: Soil-transmitted nematode, Infection rate, Surveillance, Hookworm, Ascaris lumbricoides, Trichuris trichiura

CLC Number:

R532.1

ZHU Hui-hui, HUANG Ji-lei, CHEN Ying-dan, ZHOU Chang-hai, ZHU Ting-jun, QIAN Men-bao, ZHANG Mi-zhen, LI Shi-zhu, ZHOU Xiao-nong. Analysis on endemic status of soil-transmitted nematode infection in China in 2019[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2021, 39(5): 666-673.

Figures/Tables 4

Table 1

Infection rate of soil-transmitted nematodes in the nationwide surveillance sites in 2019

省（直辖市、自治区） Province (municipality, autonomous region)	检查人数 No. exam’d	土源性线虫 Soil-transmitted nematode		钩虫 Hookworm		蛔虫 Ascaris lumbricoides		鞭虫 Trichuris trichura
省（直辖市、自治区） Province (municipality, autonomous region)	检查人数 No. exam’d	感染人数 No. infected	感染率/%Infection rate/%	感染人数 No. infected	感染率/% Infection rate/%	感染人数 No. infected	感染率/% Infection rate/%	感染人数 No. infected	感染率/% Infection rate/%
北京 Beijing	3 008	0	0	0	0	0	0	0	0
天津 Tianjin	2 028	2	0.10	0	0	2	0.10	0	0
河北 Hebei	15 239	0	0	0	0	0	0	0	0
山西 Shanxi	14 189	4	0.03	0	0	3	0.02	1	0.01
内蒙古 Inner Mongolia	10 185	0	0	0	0	0	0	0	0
辽宁 Liaoning	14 085	19	0.13	0	0	19	0.13	0	0
吉林 Jilin	12 000	39	0.33	0	0	39	0.33	0	0
黑龙江 Heilongjiang	19 082	1	0.01	0	0	1	0.01	0	0
上海 Shanghai	3 090	0	0	0	0	0	0	0	0
江苏 Jiangsu	11 538	30	0.26	11	0.10	16	0.14	3	0.03
浙江 Zhejiang	11 538	100	0.87	100	0.87	0	0	0	0
安徽 Anhui	14 982	96	0.64	78	0.52	2	0.01	16	0.11
福建 Fujian	12 686	117	0.92	100	0.79	1	0.01	16	0.13
江西 Jiangxi	14 203	159	1.12	115	0.81	33	0.23	11	0.08
山东 Shandong	14 537	127	0.87	10	0.07	16	0.11	104	0.72
河南 Henan	21 660	30	0.14	18	0.08	10	0.05	2	0.01
湖北 Hubei	10 168	2	0.02	0	0	1	0.01	1	0.01
湖南 Hunan	28 092	399	1.42	278	0.99	108	0.38	23	0.08
广东 Guangdong	22 879	68	0.30	13	0.06	21	0.09	34	0.15
广西 Guangxi	20 370	332	1.63	233	1.14	31	0.15	72	0.35
海南 Hainan	3 205	105	3.28	86	2.68	0	0	19	0.59
重庆 Chongqing	6 149	238	3.87	202	3.29	38	0.62	2	0.03
四川 Sichuan	31 292	2 518	8.05	1 849	5.91	384	1.23	455	1.45
贵州 Guizhou	14 151	312	2.20	72	0.51	150	1.06	106	0.75
云南 Yunnan	16 693	885	5.30	414	2.48	294	1.76	245	1.47
西藏 Tibet	6 441	94	1.46	0	0	85	1.32	9	0.14
陕西 Shaanxi	9 053	6	0.07	0	0	6	0.07	0	0
甘肃 Gansu	18 705	41	0.22	0	0	40	0.21	1	0.01
青海 Qinghai	7 043	43	0.61	0	0	43	0.61	0	0
宁夏 Ningxia	12 017	171	1.42	1	0.01	168	1.40	2	0.02
新疆 Xinjiang	24 458	21	0.09	0	0	17	0.07	4	0.02
合计 Total	424 766	595 9	1.40	3 580^a	0.84	1 528^a	0.36	1 126^a	0.27

Table 1

Fig. 1

Table 2

Fig. 2

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虫种Species	2018			2019			χ²	P
虫种Species	检查人数 No. exam’d	感染人数 No. infected	感染率/% Infection rate/%	检查人数 No. exam’d	感染人数 No. infected	感染率/%Infection rate/%	χ²	P
土源性线虫 Soil-transmitted nematode	75 734	1 078	1.42	79 700	1 138	1.43	0.01	> 0.05
钩虫^a Hookworm^a	75 734	754	1.00	79 700	705	0.88	5.15	< 0.05
蛔虫^a Ascaris lumbricoides^a	75 734	220	0.29	79 700	290	0.36	6.39	< 0.01
鞭虫^a Trichuris trichiura^a	75 734	138	0.18	79 700	195	0.24	7.08	< 0.01