The spatial-temporal risk profiling of Clonorchis sinensis infection in South Korea: A geostatistical modeling study

Clonorchiasis is one of the major parasitic diseases in South Korea. Spatially explicit estimates of the infection risk are important for control and intervention. We did a systematic review of collected prevalence data on Clonorchis sinensis infection in South Korea. Data of potential influencing factors (e.g., environmental and social-economic factors) was obtained from open-access databases. Bivariate Bayesian geostatistical joint modeling approaches were applied to analyze disease data, within a logit regression in combination of potential influencing factors and spatial-temporal random effects. We identified surveys of C. sinensis infection done at 1362 unique locations, and presented the first spatial-temporal risk maps at high spatial resolution (5x5km) in South Korea. High infection risk areas shrunk significantly from 1970 to 2017. The overall risk decreased since the start of the national deworming program in 1969, and then slightly increased since the year 1995 when the program suspended, and maintained stable since 2005 when the Clonorchiasis Eradication Program begun. The population-weighted prevalence was estimated as 3.87% (95% BCI: 3.04-4.82%) in 2017, accounting to 1.92 (95% BCI: 1.51-2.40) million infected people. Although the prevalence over the country has been low, C. sinensis infection was still endemic in areas of eastern and southern regions, particularly the five major river basins. We also defined factors significantly correlated, such as, distance to the nearest open water bodies, annual precipitation, and land surface temperature at night. All findings above provide important information on spatial-targeting control and preventive strategies of C. sinensis infection in South Korea.