Three Years of African Swine Fever in South Korea (2019–2021): A Scoping Review of Epidemiological Understanding

Abstract

African swine fever (ASF) is a highly contagious viral disease in domestic pigs and wild boar that causes tremendous socioeconomic damage in related industries. In 2019, the virus emerged in South Korea, which has since reported 21 outbreaks in domestic pig farms and over 2,600 cases in wild boar. In this review, we synthesize the epidemiological knowledge generated on ASF in South Korea during the first three years of the epidemic (2019–2021). We searched four international and one domestic Korean database to identify scientific articles published since 2019 and describing ASF epidemiology in South Korea. Fourteen articles met our selection criteria and were used to synthesize the origin of ASF in South Korea, the risk factors of disease occurrence, the effectiveness of the surveillance and intervention measures that were implemented, and the viral transmission dynamics. We found that timely intensive surveillance and interventions on domestic pig farms successfully blocked between-farm transmission. However, in wild boar, the ASF virus has spread massively towards the south primarily along the mountain ranges despite ongoing fence erection and intensive depopulation efforts, endangering domestic pig farms across the country. The current devastating epidemic is suspected to be the consequence of an ASF control strategy unaligned to the epidemiological context, the challenging implementation of control measures hindered by topological complexities, and inappropriate biosecurity by field workers. To improve our understanding of ASF epidemiology in South Korea and enhance disease management, future research studies should specify the ecological drivers of disease distribution and spread and devise effective control strategies, particularly in relation to Korean topography, and the latent spread of the virus in wild boar populations. Additionally, research studies should explore the psychosocial factors for ASF management, and develop tools to support evidence-based decision-making for managing ASFV in wild boar.

What can we learn from the five-year African swine fever epidemic in Asia?

“…South Korea is considered to have implemented a relatively high level of control policy with a low ASF incidence on pig farms among Asian countries ( 36 , 46 ). Contaminated vehicles and the movement of infected wild boars likely contributed to the ASFV transmission to pig farms; in particular, vehicle movement played a major role in the series of early outbreaks on farms ( 74 ).…”

“…A third fence was deployed across the country from west to east in areas 20 to 30 km away from the second fence to prevent further southward movement. Each time ASF cases were reported beyond the third fence, authorities enclosed the newly infected area ( 36 , 75 ). The effectiveness of fences in preventing the spread of disease in wildlife is controversial ( 77 ), however, its role in South Korea is emphasized as a temporary measure to slow the transmission rate ( 78 ).…”

“…Accordingly, the quarantine framework is primarily based on border control as in island countries. While previous studies derived that the ASFV-introduction risk associated with the legal importation of live pigs and/or pork products is low ( 83 ), there are concerns regarding the risk of human-mediated pathways, such as illegal pork importation ( 36 , 84 ). On the other hand, a study analyzing the distribution of ASF cases at the beginning of the epidemic identified proximity to North Korea as an important continuing risk factor ( 33 ).…”

Risk factors for African swine fever spread in wild boar in the Russian Federation

“…Обозначенная актуальность изучения вопросов биологии кабанов и устойчивости вируса АЧС в окружающей среде определяет экологические и ландшафтно-климатические факторы риска заноса и распространения инфекции как особую категорию предикторов, которые необходимо рассматривать в первую очередь [19,20].…”

Emergence and Prevalence of an African Swine Fever Virus Variant in Wild Boar Populations in South Korea from 2019 to 2022

“…In Korea, ASF has spread nationwide since the first case in wild boars in October 2019 [ 7 ]. Therefore, the Korean government has been implementing measures, including fence cutting, population control, carcass searching, and safe disposal, to control the spread of ASF in domestic wild boars [ 8 , 9 ]. Despite these efforts, new cases of ASF occurring in wild boars are still being reported in Korea.…”