Surveillance of human soil-transmitted nematode infection in Anhui Province during 2016—2020

doi:10.12140/j.issn.1000-7423.2023.01.007

Abstract

Abstract:

Objective To understand the prevalence of soil-transmitted nematode (STN) infection in Anhui Province from 2016 to 2020 to provide scientific basis for formulating the STN control strategy. Methods The surveillance for STN was performed in Anhui Province according to the National Surveillance Program for Clonorchiasis and Soil-borne Nematodiasis (provisional version) during 2016—2020. A certain number of counties (cities, districts) were selected yearly as surveillance sites, each of which was further divided into 5 sectors according to its geographic location, i.e., east, west, south, north, and central. From each sector, one township was randomly selected, and an administrative village was selected from the township to conduct surveillance. In the sampled village, no less than 200 permanent residents over 3 years old were cluster sampled. Fecal samples (> 30 g) from the enrolled residents were collected and were examined for STN eggs using the modified Kato-Katz thick smear method (two slide-reading for each sample). Children aged 3-9 were additionally examined for Enterobius vermicularis eggs with the cellophane anal swab method. The infection rate and intensity of STN were calculated and descriptively analyzed. Chi-square test and Chi-square trend test were used to compare the infection rates. Results From 2016 to 2020, 6, 16, 14, 14 and 21 surveillance sites were selected, the STN infection rate in the population in the 5 years was 2.14% (129/6 032), 0.76% (125/16 409), 1.26% (185/14 704), 0.88% (132/14 982) and 0.58% (126/21 575), respectively. The infection rate showed an overall downward trend, with a decrease of 72.90% in 2020 compared to 2016. The differences between the years were statistically significant (χ² = 143.68, P < 0.05). The infection rate of hookworm was 1.94% (117/6 032), 0.53% (87/16 409), 1.07% (158/14 704), 0.52% (78/14 982) and 0.43% (92/21 575), respectively, while that of Ascaris lumbricoides, Trichuris trichiura and E. vermicularis was relatively low (0.01%-0.24%). Among the 71 surveillance sites in the province, the highest STN infection rate was found in Qianshan City (11.02%, 103/935) in 2016, followed by Guzhen County (4.22%, 43/1 018) in 2020; and there were 19 surveillance sites with infection rate greater than 1.00%, mainly distributed in northern Anhui, accounting for 26.76% (19/71) of all the surveillance sites. From 2016 to 2020, the STN infection rate in males was 1.98% (62/3 136), 0.67% (54/8 009), 0.99% (70/7 037), 0.95% (67/7 052), 0.53% (56/10 592) and in females was 2.31% (67/2 896), 0.85% (71/8 400), 1.50% (115/7 667), 0.82% (65/7 930), 0.64% (70/10 983), respectively, there was no significant differences between genders (χ² = 0.82, 1.57, 0.73, 1.10; P > 0.05) except for 2018 (χ² = 7.54, P < 0.05). The STN infection rate showed an increasing trend with age and decreasing trend with education levels. The highest infection rate was found in the age group of "≥ 71" and the illiterate and primary school education group, which was 1.73% (11/635), 1.19% (23/1 926), 2.70% (51/1 890), 1.68% (33/1 970), 1.00% (29/2 906) and 3.08% (110/3 567), 0.99% (111/11 263), 1.63% (160/9 794), 1.14% (117/10 235), 0.61% (81/13 345), respectively. For the STN specie compositions, the composition ratio of hookworm was the highest, which was 90.70% (117/129), 69.60% (87/125), 85.41% (158/185), 59.09% (78/132) and 73.02% (92/126), respectively. For infection severety degrees, mild infection accounted for the majority, while moderate infection and severe infection were rare. Conclusion During the 13th Five-Year Plan period, the STN infection rate in Anhui Province showed a downward trend, being at a low prevalence status. Hookworm is the main infection species, and northern Anhui is the key area for STN control in the future.

Key words: Soil-transmitted nematode, Infection, Surveillance, Anhui Province

CLC Number:

R532.1

CAO Zhiguo, WANG Tianping, JIN Wei, GUO Jianduo, ZHU Lei, LIU Daohua, WANG Min, LI Qiyang, HU Mingchuang. Surveillance of human soil-transmitted nematode infection in Anhui Province during 2016—2020[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2023, 41(1): 44-51.

Figures/Tables 3

Table 1

Prevalence of soil-transmitted nematode infection in Anhui Province 2016—2020

年份 Year	县（市、区） County (City, District)	监测人数No. surveyed	土源性线虫 Soil-transmitted nematode		钩虫 Hookworm		蛔虫 A. lumbricoides		鞭虫 T. trichiura		蛲虫 E. vermicularis
年份 Year	县（市、区） County (City, District)	监测人数No. surveyed	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/%	感染人数No. infected	感染率/% Infection rate/%
2016	当涂县Dangtu	1 006	1	0.10	1	0.10	0	0	0	0	0	0
	肥东县Feidong	1 008	3	0.30	0	0	0	0	0	0	3	0.30
	灵璧县Lingbi	986	12	1.22	11	1.12	0	0	1	0.10	0	0
	潜山市Qianshan	935	103	11.02	96	10.27	4	0.43	3	0.32	0	0
	青阳县Qingyang	998	2	0.20	2	0.20	0	0	0	0	0	0
	义安区Yi’an	1 099	8	0.73	7	0.64	0	0	1	0.09	0	0
	小计Subtotal	6 032	129	2.14	117	1.94	4	0.07	5	0.08	3	0.05
2017	枞阳县Zongyang	1 015	7	0.69	5	0.49	0	0	2	0.20	0	0
	当涂县Dangtu	1 004	0	0	0	0	0	0	0	0	0	0
	砀山县Dangshan	1 009	2	0.20	2	0.20	0	0	0	0	0	0
	东至县Dongzhi	1 001	0	0	0	0	0	0	0	0	0	0
	阜南县Funan	1 003	16	1.60	12	1.20	0	0	1	0.10	4	0.40
	广德县guangde	1 037	3	0.29	3	0.29	0	0	0	0	0	0
	霍邱县Huoqiu	1 070	17	1.59	6	0.56	0	0	1	0.09	10	0.93
	旌德县Jingde	1 000	4	0.40	2	0.20	0	0	1	0.10	1	0.10
	来安县Lai’an	1 016	5	0.49	5	0.49	0	0	0	0	0	0
	庐江县Lujiang	1 071	17	1.59	16	1.49	0	0	0	0	1	0.09
	蒙城县Mengcheng	1 035	11	1.06	7	0.68	0	0	0	0	4	0.39
	寿县Shouxian	1 050	15	1.43	7	0.67	0	0	2	0.19	6	0.57
	宿松县Susong	1 042	3	0.29	1	0.10	0	0	0	0	2	0.19
	濉溪县Suixi	1 010	2	0.20	2	0.20	0	0	0	0	0	0
	桐城市Tongcheng	1 038	18	1.73	15	1.45	1	0.10	2	0.19	0	0
	五河县Wuhe	1 008	5	0.50	4	0.40	1	0.10	0	0	0	0
	小计Subtotal	16 409	125	0.76	87	0.53	2	0.01	9	0.05	28	0.17
2018	巢湖市Chaohu	1 029	2	0.19	0	0	0	0	0	0	2	0.19
	固镇县Guzhen	1 071	28	2.61	27	2.52	0	0	0	0	1	0.09
	和县Heixian	1 025	0	0	0	0	0	0	0	0	0	0
	怀宁县Huaining	1 037	20	1.93	20	1.93	0	0	0	0	0	0
	郎溪县Langxi	1 126	24	2.13	22	1.95	1	0.09	1	0.09	0	0
	蒙城县Mengcheng	1 012	4	0.40	3	0.30	0	0	0	0	1	0.10
	明光市Mingguang	1 075	4	0.37	3	0.28	0	0	1	0.09	0	0
	寿县Shouxian	1 055	9	0.85	2	0.19	0	0	2	0.19	5	0.47
	舒城县Shucheng	1 007	35	3.48	34	3.38	0	0	0	0	1	0.10
	泗县Sixian	976	9	0.92	8	0.82	0	0	0	0	1	0.10
	濉溪县Suixi	1 020	4	0.39	2	0.20	0	0	2	0.20	0	0
	太和县Taihe	1 136	21	1.85	13	1.14	0	0	2	0.18	6	0.53
	屯溪区Tunxi	1 132	21	1.86	20	1.77	0	0	0	0	1	0.09
	义安区Yi’an	1 003	4	0.40	4	0.40	0	0	0	0	0	0
	小计Subtotal	14 704	185	1.26	158	1.07	1	0.01	8	0.05	18	0.12
2019	枞阳县Zongyang	1 036	7	0.68	5	0.48	1	0.10	1	0.10	0	0
	肥西县Feixi	1 055	10	0.95	8	0.76	0	0	2	0.19	0	0
	贵池区Guichi	1 624	6	0.37	0	0	0	0	4	0.25	2	0.12
	含山县Hanshan	1 035	5	0.48	2	0.19	0	0	0	0	3	0.29
	怀远县Huaiyuan	1 009	5	0.50	3	0.30	0	0	0	0	2	0.20
	界首市Jieshou	1 089	20	1.84	8	0.73	1	0.09	0	0	11	1.01
	泾县Jingxian	1 002	2	0.20	0	0	0	0	2	0.20	0	0
	蒙城县Mengcheng	1 002	9	0.90	8	0.80	0	0	0	0	1	0.10
	全椒县Quanjiao	1 028	7	0.68	0	0	0	0	4	0.39	3	0.29
	寿县Shouxian	1 077	15	1.39	7	0.65	0	0	0	0	8	0.74
	舒城县Shucheng	1 010	30	2.97	27	2.67	0	0	1	0.10	2	0.20
	濉溪县Suixi	1 008	1	0.10	1	0.10	0	0	0	0	0	0
	太湖县Taihu	1 004	6	0.60	6	0.60	0	0	0	0	0	0
	萧县Xiaoxian	1 003	9	0.90	3	0.30	0	0	2	0.20	4	0.40
	小计Subtotal	14 982	132	0.88	78	0.52	2	0.01	16	0.11	36	0.24
2020	大观区Daguan	1 005	1	0.10	0	0	0	0	1	0.10	0	0
	当涂县Dangtu	1 009	0	0	0	0	0	0	0	0	0	0
	凤阳县Fengyang	1 013	3	0.30	1	0.10	0	0	1	0.10	2	0.20
	固镇县Guzhen	1 018	43	4.22	43	4.22	0	0	0	0	0	0
	和县Hexian	1 044	0	0	0	0	0	0	0	0	0	0
	铜陵市郊区 Jiaoqu, Tongling	1 025	0	0	0	0	0	0	0	0	0	0
	金寨县Jinzhai	1 012	9	0.89	8	0.79	0	0	0	0	1	0.10
	临泉县Linquan	1 001	29	2.90	12	1.20	0	0	1	0.10	16	1.60
	蒙城县Mengcheng	1 021	4	0.39	4	0.39	0	0	0	0	0	0
	南陵县Nanling	1 082	4	0.37	4	0.37	0	0	0	0	0	0
	宁国市Ningguo	1 001	1	0.10	0	0	0	0	1	0.10	0	0
	潘集区Panji	1 095	0	0	0	0	0	0	0	0	0	0
	石台县Shitai	1 105	0	0	0	0	0	0	0	0	0	0
	望江县Wangjiang	1 008	1	0.10	0	0	0	0	1	0.10	0	0
	无为市Wuwei	1 033	3	0.29	2	0.19	0	0	0	0	1	0.10
	相山区Xiangshan	1 003	1	0.10	1	0.10	0	0	1	0.10	0	0
	宣州区Xuanzhou	1 004	6	0.60	5	0.50	0	0	1	0.10	0	0
	黟县Yixian	1 019	6	0.59	5	0.49	0	0	0	0	1	0.10
	义安区Yi’an	1 002	2	0.20	1	0.10	1	0.10	0	0	0	0
	埇桥区Yongqiao	1 000	7	0.70	3	0.30	0	0	1	0.10	3	0.30
	长丰县Changfeng	1 075	6	0.56	3	0.28	2	0.19	0	0	1	0.09
	小计Subtotal	21 575	126	0.58	92	0.43	3	0.01	8	0.04	25	0.12

Table 1

Table 2

Table 3

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年龄组/岁 Age group/Year	土源性线虫感染率/% Infection rate of soil-transmitted nematode/%
年龄组/岁 Age group/Year	2016	2017	2018	2019	2020
0~10	1.22（6/490）	1.41（32/2 262）	1.02（20/1 960）	1.53（39/2 551）	1.05（28/2 666）
11~20	0.69（3/432）	0.22（2/916）	0（0/816）	0.30（3/993）	0.12（2/1 674）
21~30	1.60（5/312）	0.44（4/899）	0.35（3/862）	0.14（1/719）	0.42（5/1 197）
31~40	1.02（5/489）	0.59（7/1 178）	0.27（3/1 110）	0.27（3/1 120）	0.22（4/1 799）
41~50	2.11（26/1 232）	0.30（8/2 648）	0.72（16/2 233）	0.38（7/1 841）	0.38（11/2 911）
51~60	2.70（34/1 261）	0.51（16/3 159）	1.08（30/2 765）	0.48（14/2 908）	0.50（24/4 764）
61~70	3.31（39/1 178）	0.96（33/3 420）	2.02（62/3 068）	1.11（32/2 880）	0.63（23/3 658）
≥ 71	1.73（11/635）	1.19（23/1 926）	2.70（51/1 890）	1.68（33/1 970）	1.00（29/2 906）

年份 Year	构成比/% Composition ratio/%
年份 Year	钩虫 Hookworm	蛔虫 A. lumbricoides	鞭虫 T. trichiura	蛲虫 E. vermicularis
2016	90.70（117/129）	3.10（4/129）	3.88（5/129）	2.33（3/129）
2017	69.60（87/125）	1.60（2/125）	7.20（9/125）	22.40（28/125）
2018	85.41（158/185）	0.54（1/185）	4.32（8/185）	9.73（18/185）
2019	59.09（78/132）	1.52（2/132）	12.12（16/132）	27.27（36/132）
2020	73.02（92/126）	2.38（3/126）	6.35（8/126）	19.84（25/126）