Epidemiological analysis of soil-transmitted nematode infections in China in 2020

doi:10.12140/j.issn.1000-7423.2023.03.011

Abstract

Abstract:

Objective To understand the situation of soil-transmitted nematode infection in China in 2020 and provide support for evaluating the development of surveillance on soil-transmitted nematodiasis in various provinces/municipalities/autonomous regions, and improving and perfecting the control strategies. Methods Surveillance was carried out in 408 national surveillance sites (counties) in 31 provinces (municipalities, autonomous regions) in China in 2020. With the county as unit, each site was divided into 5 areas geographically: east, west, south, north, and central part, followed by selecting one township (town), and therein one administrative village was selected from wherein, 200 permanent residents over the age of 3 were sampled. A total of 1 000 people were surveyed at each surveillance site. Fecal samples were collected from the sampled villagers, and examined by using the modified Kato-Katz thick smear method (two slide-reading for each sample) for infection of hookworm, Ascaris lumbricoides, Trichuris trichiura and Enterobius vermicularis, to calculate the infection rate and intensity, respectively. In addition, soil samples were collected from fields or vegetable gardens of each village in the survey site, and examined for hookworm larvae using 5% saline at 45 ℃, and for Ascaris eggs by saturated sodium nitrate flotation method. Results In 2020, the overall infection rate of soil-transmitted nematode in residents was 0.84% (3 485/415 672) in 408 surveillance sites of 31 provinces (municipalities/autonomous regions), with the highest found in Hainan (6.34%, 199/3 141), followed by Yunnan (5.80%, 963/16 616) and Sichuan (3.66%, 592/16 168); infection rate in females was 0.91% (1 944/213 591), which was higher than that of 0.76% in males (1 541/202 081) (χ² = 27.20, P < 0.01). The soil-transmitted nematode infection rate was the highest in the age group ≥ 60-years-old, which is 1.26% (1 376/109 251). The difference between each age group was statistically significant (χ² = 382.28, P < 0.01). The infection rates of hookworm, A. lumbricoides, T. trichiura were 0.51% (2 016/415 672), 0.19% (805/415 672) and 0.16% (673/415 672), respectively. Among them, hookworm and T. trichiura had only mildly infected cases. The proportions of mild and moderate A. lumbricoides infections were 99.25% (799/805) and 0.75% (6/805), respectively. In 2020, 2 604 soil samples were examined and found that the positive rate of Ascaris eggs and hookworms was 3.07% (80/2 604) and 2.42% (63/2 604), respectively. Conclusion In 2020, the infection rate of soil-transmitted nematode in China remains at a low level in general, but the regional differences are still significant, and the areas with high infection rates still exist. At the same time, it is necessary to strengthen the control measures for the key groups of people over age of 60, women and children, and carry out health education.

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

CLC Number:

R532.1

ZHANG Mizhen, HUANG Jilei, ZHU Huihui, ZHOU Changhai, ZHU Tingjun, QIAN Menbao, CHEN Yingdan, LI Shizhu. Epidemiological analysis of soil-transmitted nematode infections in China in 2020[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2023, 41(3): 331-335.

Figures/Tables 2

Table 1

The infection of soil-transmitted nematode in national surveillance sites in 2020

省（直辖市、自治区） Province (Municipality, Autonomous Region)	监测点数 No. surveillance site	监测人数 No. surveyed	土源性线虫 Soil-transmitted nematode		钩虫 Hookworm		蛔虫 Ascaris lumbricoides		鞭虫 Trichuris trichiura
省（直辖市、自治区） Province (Municipality, Autonomous Region)	监测点数 No. surveillance site	监测人数 No. surveyed	总感染人数 No. infected	总感染率/% Overall 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	3 055	0	0	0	0	0	0	0	0
天津 Tianjin	2	2 015	4	0.20	0	0	4	0.20	0	0
河北 Hebei	14	14 173	0	0	0	0	0	0	0	0
山西 Shanxi	18	18 019	4	0.02	0	0	4	0.02	0	0
内蒙古 Inner Mongolia	10	10 018	0	0	0	0	0	0	0	0
辽宁 Liaoning	14	14 071	15	0.11	0	0	13	0.09	2	0.01
吉林 Jilin	12	12 000	30	0.25	0	0	30	0.25	2	0.02
黑龙江 Heilongjiang	19	19 194	0	0	0	0	0	0	0	0
上海 Shanghai	3	3 135	0	0	0	0	0	0	0	0
江苏 Jiangsu	11	11 248	21	0.19	6	0.05	11	0.10	4	0.04
浙江 Zhejiang	10	10 171	59	0.58	59	0.58	0	0	0	0
安徽 Anhui	21	21 554	101	0.47	92	0.43	3	0.01	8	0.04
福建 Fujian	12	12 536	92	0.73	80	0.64	0	0	12	0.10
江西 Jiangxi	14	14 282	92	0.64	72	0.5	17	0.12	3	0.02
山东 Shandong	14	14 436	106	0.73	4	0.03	18	0.12	84	0.58
河南 Henan	19	19 496	38	0.19	23	0.12	8	0.04	7	0.04
湖北 Hubei	10	10 234	5	0.05	0	0	1	0.01	4	0.04
湖南 Hunan	38	38 032	284	0.75	164	0.43	106	0.28	19	0.05
广东 Guangdong	28	28 879	83	0.29	46	0.16	14	0.05	25	0.09
广西 Guangxi	16	16 442	246	1.50	202	1.23	7	0.04	39	0.24
海南 Hainan	3	3 141	199	6.34	166	5.28	1	0.03	32	1.02
重庆 Chongqing	6	6 155	76	1.23	69	1.12	5	0.08	2	0.03
四川 Sichuan	16	16 168	592	3.66	500	3.09	88	0.54	12	0.07
贵州 Guizhou	14	14 075	255	1.81	54	0.38	125	0.89	102	0.72
云南 Yunnan	16	16 616	963	5.80	569	3.42	132	0.79	314	1.89
西藏 Xizang	7	7 082	118	1.67	0	0	116	1.64	2	0.03
陕西 Shaanxi	9	9 130	0	0	0	0	0	0	0	0
甘肃 Gansu	18	17 698	11	0.06	0	0	11	0.06	0	0
青海 Qinghai	8	8 304	49	0.59	0	0	49	0.59	0	0
宁夏 Ningxia	10	10 772	22	0.20	0	0	22	0.20	0	0
新疆 Xinjiang	13	13 541	20	0.15	0	0	20	0.15	0	0
合计 Total	408	415 672	3 485	0.84	2 106	0.51	805	0.19	673	0.16

Table 1

Fig. 1

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