Clonorchiasis in China: Geospatial modeling of the population infected and at risk, based on national surveillance

Abstract

Objectives: Clonorchiasis is highly endemic in China. The unavailability of fine-scale distribution of population with infection and at risk hinders the control.

Methods: This study established Bayesian geostatistical models to estimate age- and gender-specific prevalence of Clonorchis sinensis infection at high spatial resolution (5 × 5 km²), based on the surveillance data in China between 2016 and 2021, together with socioeconomic, environmental and behavioral determinants. The population at risk and under infection, as well as chemotherapy need were then estimated.

Results: In 2020, population-weighted prevalence of 0.67% (95% Bayesian credible interval (BCI): 0.58%-0.77%) was estimated for C. sinensis infection in China, corresponding to 9.46 million (95% BCI: 8.22 million-10.88 million) persons under infection. High prevalence was demonstrated in southern areas, including Guangxi (8.92%, 95% BCI: 7.10%-10.81%) and Guangdong (2.99%, 95% BCI: 2.43%-3.74%). A conservative estimation of 99.13 million (95% BCI: 88.61 million-114.40 million) people were at risk of infection, of which 51.69 million (95% BCI: 45.48 million-57.84 million) need chemotherapy.

Conclusions: Clonorchiasis is an important public health problem in China, especially in southern areas, due to the huge population at risk and large number of people under infection. Implementation of chemotherapy is urged to control the morbidity.

Keywords: Bayesian geostatistical model; Clonorchiasis; Clonorchis sinensis; Surveillance.