A new method for estimating the prevalence of clonorchiasis in Korea

Abstract

South Korea presently uses an arbitrary sampling method to monitor the prevalence of Clonorchis sinensis infection in the endemic areas of the country. However, the present method is not standardized and focuses primarily on individuals who reside nearest to the mainstream river. We propose a new sampling method that combines cluster sampling with proportionate quota sampling to ensure that the entire endemic area is accurately represented. We tested the new method in Okcheon-gun, South Korea, and determined that the C sinensis infection prevalence (8.9%) in 2013 was higher than that (6.9%) estimated in 2012 when the arbitrary method was used. Additionally, no difference was observed in the prevalence based on the distance from the riverside areas, including branches and creeks, between the areas <1 and >1 km away from the riversides. Therefore, health authorities should place equal emphasis on all regions within the endemic areas. Based on the findings, we recommend the following: the clonorchiasis prevalence rate must be measured using probability sampling, (clear guidelines on survey coverage should be provided to include the riverside areas and all areas nearby branch streams, and regional cohorts should be created for continuous monitoring of prevalence rates across the region.

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

“…This suggested that the prevention C. sinensis infection in rural areas should not be neglected. We found that distance to the nearest water bodies had a negative effect with C. sinensis infection, consistent with knowledge that inhabitants living closer to waterbodies had more chance of freshwater fish consumption ( Jeong et al, 2017; Lai et al, 2017 ). The above finding suggested the rural elderly population in the river basins should be prioritized for effective control and prevention of C. sinensis infection.…”

“…Of note, CEP seemed effective in certain sense, at least the overall infection risk did not increase but remain stable since 2005. In practice, the CEP started in different times across different areas with different intensity of implementation, which may lead to different local trends of infection risk ( Jeong et al, 2017 ).…”

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

“…We found that surveys using FE or combined the two diagnostic methods (i.e., FE and Kato-Katz) tended to report higher prevalence than that using Kato-Katz method, in line with the previous studies. 30 Distance to the nearest water bodies was found negative associated with infection risk, consistent with knowledge that inhabitants living closer to waterbodies had more chance of freshwater fish consumption, 18 , 21 suggesting that residents living in the river basins should be prioritized for effective control and prevention of the disease. Our results showed that the infection risk was negatively associated with HII, indicating the disease was more common in areas with low levels of human activities, which tended to be remote, poorly educated, and economically underdeveloped.…”

“…In practice, the two national programs started in different times in different areas with different intensity of implementation, which may lead to different local trends of infection risk. 15 , 18 …”

“…The second program was the Clonorchiasis Eradication Program (CEP) implemented by the Korea Centers for Disease Control and Preventions (KCDC) from 2005, with the goal to reduce the infection rate by diagnosing, treating, and educating residents in endemic areas. 14 , 16 , 17 Since the two programs were launched in different areas at different time and with different implementation efforts, it is important to evaluate the effectiveness of the programs comprehensively in different areas across the country, 18 which has not be done to our knowledge. Only a few ones conducted assessment in localized areas or among selected populations, such as Kim et al.…”