The spatial-temporal risk profiling of <i>Clonorchis sinensis</i> infection over 50 years implies the effectiveness of control programs in South Korea: a geostatistical modeling study.

Abstract

Over the past 50 years, two national control programs on <i>Clonorchis sinensis</i> infection have been conducted in South Korea. Spatial-temporal profiles of infection risk provide useful information on assessing the effectiveness of the programs and planning spatial-targeted control strategies. Advanced Bayesian geostatistical joint models with spatial-temporal random effects were developed to analyze disease data collecting by a systematic review with potential influencing factors, and to handle issues of preferential sampling and data heterogeneities. Changes of the infection risk were analyzed. We presented the first spatial-temporal risk maps of <i>C. sinensis</i> infection at 5 × 5 km² resolution from 1970 to 2020 in South Korea. Moderate-to-high risk areas were shrunk, but temporal variances were shown in different areas. The population-adjusted estimated prevalence across the country was 5.99% (95% BCI: 5.09-7.01%) in 1970, when the first national deworming campaign began. It declined to 3.95% (95% BCI: 2.88-3.95%) in 1995, when the campaign suspended, and increased to 4.73% (95% BCI: 4.00-5.42%) in 2004, just before the Clonorchiasis Eradication Program (CEP). The population-adjusted prevalence was estimated at 2.77% (95% BCI: 1.67-4.34%) in 2020, 15 years after CEP started, corresponding to 1.42 (95% BCI: 0.85-2.23) million infected people. The first nationwide campaign and the CEP showed effectiveness on control of <i>C. sinensis</i> infection. Moderate-to-high risk areas identified by risk maps should be prioritized for control and intervention. The National Natural Science Foundation of China (project no. 82073665) and the Natural Science Foundation of Guangdong Province (project no. 2022A1515010042).