A comparative analysis of baseline and post-intervention surveillance in a hookworm control pilot: Evidence from Tiantai County, Zhejiang Province, 2022–2024

Hookworm infection remains a neglected tropical disease in rural areas where low-level transmission may persist despite long-term control efforts. This repeated cross-sectional study evaluated changes in hookworm infection in six rural villages of Tiantai County, Zhejiang Province, China, before and after implementation of an integrated control program. In 2022, approximately 200 permanent residents aged ≥3 years were sampled from each village for the baseline survey. After one year of integrated interventions, including sanitation improvement, health education, deworming, and strengthened village-level management, another cross-sectional survey was conducted in the same villages in 2024. Hookworm infection was detected using stool examination. Prevalence was compared between survey years, and Firth penalized logistic regression was used to estimate adjusted associations with infection while addressing sparse data and complete separation. A total of 1,218 individuals were examined in 2022, of whom 58 were positive for hookworm infection, corresponding to a prevalence of 4.76%. In 2024, 1,222 individuals were examined and 13 infections were detected, corresponding to a prevalence of 1.06%. The overall prevalence decreased by 77.73%. In the Firth penalized logistic regression model adjusted for sex, age group, educational level, occupation, and village, the odds of infection in the 2024 post-intervention survey were significantly lower than those in the 2022 baseline survey (adjusted OR = 0.223, 95% CI: 0.125-0.399, P < 0.001). Male sex, primary education or below, and residence in Qianyang, Xiatang, or Xiaqiao villages were associated with higher infection odds. Hookworm prevalence declined substantially in the same villages after implementation of integrated control measures. However, the absence of non-intervention control villages limits causal attribution. Sustained surveillance and targeted interventions remain needed for high-risk populations and villages.