[Familial aggregation of human hookworm infections in Sichuan Province]

Objective: To investigate the family aggregation of human hookworm infections in Sichuan Province and to identify its influencing factors, so as to provide insights into management of hookworm infections.

Methods: Three to four counties (districts) were sampled from basins, hilly regions and mountainous regions around the basins in Sichuan Province from 2017 to 2022 as fixed survey sites, and 17 to 30 counties (districts) were selected as mobile survey sites. At least 1 000 permanent residents at ages of 3 years and older were sampled from each survey site, and hookworm eggs were detected in human stool samples using the Kato-Katz technique. Subjects with 2 and more family members and at least 2 individuals diagnosed with hookworm infections in the county (district) where they lived were selected, and the familial aggregation of hookworm infections was analyzed using the test of goodness of fit for binomial distribution. In addition, the knowledge and practice of hookworm disease control were investigated among residents in Hejiang County and Wutongqiao District, Leshan City, Sichuan Province in 2021 and 2022, and the difference in the knowledge and practice of hookworm disease control was compared between members with and without familial aggregation of hookworm infections.

Results: A total of 66 812 residents from 25 196 households were sampled from main endemic areas of hookworm diseases in Sichuan Province from 2017 to 2022 for detection of hookworm infections, and 4 403 infections were identified (6.59% prevalence). The distribution of human hookworm infections in Sichuan Province did not fit the binomial distribution, and showed family aggregations (χ² = 2 116.759, P < 0.001). Family aggregation of human hookworm infections was found in endemic areas with 1% and higher prevalence of human hookworm infections (χ² = 136.006 to 428.738, all P values < 0.001), and family aggregation of human hookworm infections was identified in different years (χ² = 87.615 to 471.838, all P values < 0.001) and in different terrains of endemic areas (χ² = 8.423 to 1 144.176, all P values < 0.001). The members with hookworm infections had median eggs per gram of 180 (interquartile range, 780) in aggregated families and 72 (102) in non-aggregated families (Z = -2.686, P < 0.05). The proportion of members in families with aggregation of hookworm infections who knew the preventive measures of hookworm disease was significantly lower than in non-aggregated families (24.49% vs. 51.72%; χ² = 10.262, P < 0.05), and the proportion of members in families with aggregation of hookworm infections who often worked barefoot on the ground was significantly higher than in non-aggregated families (30.61% vs. 13.25%; χ² = 6.289, P < 0.05).

Conclusions: There is a familial aggregation of human hookworm infections in Sichuan Province, and awareness of preventive measures for hookworm disease and frequent working barefoot on the ground are associated with familial aggregation of hookworm infections.