Abstract:

In order to investigate the current prevalence and risk factors of hookworm infections among agricultural planters in Rongchang District, Chongqing Municipality, agricultural planters were sampled using a random cluster sampling method from 5 natural villages in eastern, western, southern, northern and central parts of Rongchang District, Chongqing Municipality in 2024, and participants’ socio-demographic characteristics, living environments, agricultural labor style, and hygiene habits were collected through questionnaire surveys. Participants’ stool samples (> 30 g) were collected, and hookworm infection was detected using a Kato-Katz technique (two slides of one stool sample). Soil samples were collected from households with moderate and severe hookworm infections (one soil sample from each outdoor field or vegetable garden and one sample from a shaded area neighboring the toilet) for hookworm larval isolation. The ITS2 gene sequence of Necator americanus and the 5.8S rRNA gene sequence of Ancylostoma duodenale were amplified using multiplex PCR assay, and a phylogenetic tree was created using the neighbor-joining (NJ) method. Differences of prevalence of hookworm infections were compared with Chi-square test and Chi-square test for trend, and the independent risk factors of hookworm infections were identified using a conditional logistic regression model. The prevalence of hookworm infections was 14.9% (84/563) among 563 participants, with a mean infection intensity of 841.4, and the proportions of mild, moderate, and severe infections were 57.1% (48/84), 34.5% (29/84), and 8.3% (7/84), respectively. The participants had no history of examination or treatment for intestinal parasites during the past 5 years, and had no complaints of any hookworm infections-related symptoms or signs. Age of ≥ 60 years (17.7%, 65/367), an education level of illiteracy (27.8%, 10/36), annual family income < 20 000 RMB (20.1%, 59/294), annual growing labor duration of one month and longer (17.7%, 73/412), use of pit toilets (2/10), growing dryland crops (15.7%, 84/534), use of human feces as fertilizers (20.6%, 75/364), frequent/occasional barefoot labors (21.3%, 68/320), frequent/occasional consumption of food falling to the ground without washing (18.6%, 54/291), frequent/occasional drinking of unboiling water (18.2%, 53/291), frequent/occasional not handwashing post-defecation (21.8%, 58/266) resulted in a relatively higher incidence rate of hookworm infections among participants (χ² = 8.022, 8.920, 15.780, 9.476, 9.793, 4.194, 26.213, 23.402, 6.275, 5.145, 18.827, all P < 0.05), and the prevalence of hookworm infections increased with age, reduced educational levels, decreased annual household incomes and poor hygiene of household toilets (χ²_trend = 7.105, 8.836, 8.836, 7.121, all P < 0.05). Conditional logistic regression analysis identified use of human feces as fertilizers [odds ratio (OR) = 4.041, 95% confidence interval (CI): (1.937, 8.429)] and barefoot labor [OR = 2.726, 95% CI: (1.506, 4.935)] as independent risk factors for hookworm infections among agricultural planters. Hookworm larvae were isolated from 60 soil samples, and PCR assay tested positive in 6 samples, which were all characterized as N. americanus. It is recommended to intensify the surveillance and treatment of hookworm infections, implement health education and health behavior interventions among high-risk populations, improve toilet environmental modifications and harmless treatment of night soil in rural areas, and block the transmission routes of hookworm infection, in order to effectively reduce the risk of transmission of hookworm disease.

Key words: Hookworm, Agricultural grower, Prevalence of infection, Risk factor