Epidemiological analysis of cystic echinococcosis and alveolar echinococcosis in an extremely high prevalence region: Population-based survey and host animal monitoring in Shiqu County, China

Abstract

Echinococcosis is the most common parasitic disease in the Tibetan Plateau, placing a large disease burden on the local population. Shiqu County, located in western Sichuan Tibetan region, had a particularly high prevalence rate of cystic echinococcosis (CE) and alveolar echinococcosis (AE) in previous surveys. From 2015 to 2018, a population-based field survey was conducted to explore the epidemic situation. Epidemiological features were examined through demographic analysis and mapping. In addition, the infection prevalence of Echinococcus in dogs was also investigated and mapped by spatial autoregression. A total of 84,768 people were screened by abdominal ultrasound inspection, and 2,341 CE and 3,930 AE cases were detected, with a corresponding prevalence of 2.76% and 4.64%, respectively. This made Shiqu County one of the most severe echinococcosis endemic regions in the world, especially with regard to AE. The cases were not evenly distributed among towns: particularly, the AE rates in the northwest towns were very high and closely related to the infection rate of neighboring host animals. Simultaneously, a comprehensive prevention project including patient treatment and host management was conducted and achieved preliminary success in source control. According to feces monitoring findings, the infection rate of dogs declined from 26.38% in early 2016 to 3.71% in 2018. Combined with host animal distribution data at the town level, the predicted risk ranks were categorized by risk index and mapped to guide further control operations.