CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES ›› 2023, Vol. 41 ›› Issue (1): 59-67.doi: 10.12140/j.issn.1000-7423.2023.01.009

• ORIGINAL ARTICLES • Previous Articles     Next Articles

Epidemiological trends of soil-transmitted nematode infections in Jiangxi Province, 2015—2021

CHEN Zhe(), GE Jun, JIANG Weisheng, QIU Tingting, WEN Qi, ZENG Xiaojun*()   

  1. Jiangxi Provincial Institute of Parasitic Diseases Control, Nanchang 330096, China
  • Received:2022-06-16 Revised:2022-09-16 Online:2023-02-28 Published:2023-02-26
  • Contact: * E-mail: zengxiaojunnc@163.com
  • Supported by:
    Key Laboratory of Schistosomiasis Prevention and Control Science(2019BCD40006);Medical Leading Disciplines of Schistosomiasis Epidemiology(2021030107)

Abstract:

Objective To understand and analyze the endemic status and transmission trends of soil-transmitted helminth (STH) infection in Jiangxi Province during 2015—2020 to provide scientific basis for formulating strategy of transmission control and interruption, and evaluate the control effect. Methods From 2015 to 2021, 13, 86, 86, 86, 86, 24 and 24 counties (cities and districts) in Jiangxi Province were selected as national surveillance sites and provincial surveillance sites. The surveillance sites were randomly selected from five geographical sections in the east, west, south, north and center, from each section, one administrative village in one township (town) was randomly selected as surveillance site. Fecal samples were collected from each enrolled participant and examined for STH eggs (two slide-reading each sample) using the modified Kato-Katz thick smear method. The infection rate and intensity of different worm species were calculated, and the infection prevalence in different eco-region was analyzed. The disposable income data of rural residents in Jiangxi Province were collected from Jiangxi Statistical Yearbook from 2015 to 2021. A questionnaire based survey was conducted to collect information on the construction of sanitary toilets in each surveillance site from the village committee from 2016 to 2021. The infection rate and constituent ratio were compared by the Chi-square test. The correlation study was conducted using Pearson correlation analysis. Results From 2015 to 2021, the infection rates of STH were 1.8% (126/7 137), 1.3% (947/71 766), 1.1% (803/70 547), 0.9% (604/69 507), 0.9% (628/69 620), 0.7% (151/21 884) and 0.9% (202/21 757) respectively, showing a decreasing trend year by year, with statistically significant differences in infection rates between years (χ2 = 158.639, P < 0.01). From 2015 to 2021, the infection rates of hookworm were 1.1% (82/7 137), 0.6% (466/71 766), 0.6% (450/70 547), 0.5% (336/69 507), 0.5% (362/69 620), 0.4% (98/21 884) and 0.7% (148/21 757) respectively. From 2015 to 2021, the infection rates of Ascaris lumbricoides were 0.3% (24/7 137), 0.5% (393/71 766), 0.4% (287/70 547), 0.3% (221/69 507), 0.3% (225/69 620), 0.2% (40/21 884) and 0.2% (42/21 757) respectively. From 2015 to 2021, the infection rates of Trichuris trichiura were 0.3% (21/7 137), 0.2% (125/71 766), 0.1% (74/70 547), 0.1% (57/69 507), 0.1% (49/69 620), 0.1% (13/21 884) and 0.1% (14/21 757) respectively. The infection rates of hookworm, A. lumbricoides and T. trichiura were significantly different between years (χ2 = 75.456, 112.506, 75.383, all P < 0.01). From 2015 to 2021, the infection rates were 2.0% (73/3 623), 1.3% (469/35 788), 1.1% (378/35 207), 0.8% (273/34 703), 0.9% (295/34 801), 0.6% (65/11 110) and 0.8% (88/10 620) in males and 1.5% (53/3 514), 1.3% (478/35 978), 1.2% (425/35 340), 1.0% (331/34 804), 1.0% (333/34 819), 0.8% (86/10 774) and 1.0% (114/11 137) in females. The infection rates of male and female were significantly different between years (χ2 = 122.146, 49.615, P < 0.01). The infection rates of female were statistically higher than that of males in 2018 (χ2 = 5.450, P < 0.05). From 2015 to 2021, the infection rates of soil-transmitted nematodes were the highest in the over-70-year-old age group, which were 3.4% (19/554), 2.3% (129/5 559), 2.1% (127/5 965), 2.0% (129/6 507), 1.7% (119/7 105), 1.3% (36/2 811) and 2.1% (68/3 177) respectively, with statistically significant differences in infection rates among the different age groups (χ2 = 39.763, 150.459, 212.140, 219.129, 132.674, 43.997, 115.627, P < 0.01). From 2015 to 2021, the severely infected accounted for 1.2% (1/82), 3.9% (18/466), 1.3% (6/450), 1.5% (5/336), 0.3% (1/362), 2.0% (2/98) and 5.4% (8/148) of the total hookworm infected villagers, respectively. The differences of constituent ratio in each year were statistically significant (χ2 = 22.853, P < 0.01). Severe A. lumbricoides infection was only detected in 2016, accounting for 1.0% (4/393) of the total A. lumbricoides infection cases. T.trichiura severe infection were only detected in 2015, accounting for 4.8% (1/21) of the total T. trichiura infection cases. The infection rates of STH in 2016—2017 and 2019—2021 were the highest in Zhejiang-Fujian mountain and hill ecological regions. They were 2.3% (316/13 852), 1.5% (217/14 402), 1.4% (194/14 063), 1.2% (69/5 527) and 1.1% (60/5 535) respectively. In 2015 and 2018, the highest infection rates were 2.5% (63/2 471) and 1.2% (234/18 883) in Hunan-Jiangxi hill and mountain and Yangtze River basin ecological region, respectively. The differences in infection rates among different ecological regions in each year were statistically significant (χ2 = 21.112, 156.920, 67.104, 73.315, 73.493, 37.022, 9.351, P < 0.01 or P < 0.05). From 2015 to 2021, the disposable income of rural residents in Jiangxi Province were 10 117, 11 139, 12 138, 13 242, 14 460, 15 796 and 16 981 yuan and the coverage rates of sanitary latrines in surveillance villages were 82.7% (200 994/243 000), 85.7% (256 437/299 398), 87.3% (257 553/294 951), 88.9% (250 381/281 699), 92.1% (69 428/75) and 93.8% (77 259/82 376), respectively. The infection rates of soil-transmitted nematodes in Jiangxi Province were negatively correlated with the disposable income data among the rural residents (r = -0.834, P < 0.05) while were no correlation with the coverage rate of sanitary latrines in surveillance villages (r = -0.799, P > 0.05) in Jiangxi Province during 2016—2021. Conclusion The infection rate of STH in Jiangxi Province in 2016—2021 shows an overall decline year by year, suggesting a low transmission trend. The infection rate in 41 counties has reduced to below 1.0% for 3 consecutive years.

Key words: Soil-transmitted helminth, Surveillance, Hookworm, Ascaris lumbricoides, Trichuris trichiura, Jiangxi Province

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