African swine fever (ASF) was first reported in South Korea in September 2019, and as of 31 December 2021, a total of 21 cases in domestic pig farms and 1875 ASFV-infected wild boars have been confirmed in the country. With the continued circulation of ASF in wild boars, and subsequent outbreaks in domestic pigs, concerns were raised about the possible changes in virulence occurring among African swine fever viruses (ASFV) circulating in South Korea. In this study, four Korean ASFV strains isolated from domestic pig farms at different time points between 2019 and 2021 were chosen, and used to experimentally infect domestic pigs by intramuscular inoculation to compare their virulence. All challenged pigs died at 4–9 days post-inoculation, with many showing clinical symptoms of fever, depression, loss of appetite, and recumbency. Gross lesions observed at necropsy included enlargement and hemorrhage of the lymph nodes and hydropericardium. The study showed that all four Korean ASFV isolates caused acute forms of illness, which supports the view that virulence among the circulating ASFV isolates in South Korea remained unchanged and highly virulent during this period.

The bluetongue virus (BTV) is a significant animal pathogen with economic implications in the ruminant industry. Despite global reports on BTV detection and epidemiologic investigations, limited studies have focused on the virus in the ROK. In this study, BTV epidemiological research was conducted on blood samples from cattle and goat farms across nine regions during 2013–2014. The results showed that 3.33% of bovine blood samples (194/5824) and 0.19% of goat blood samples (2/1075) tested positive for BTV antibodies using ELISA. In Jeju-do, BTV RNA amplification occurred in 51 of 422 samples (12.1%) using real-time reverse transcription (RT-qPCR). The isolation of one sample revealed it as serotype 3, as indicated by the sequence of segments 2 (Seg-2) and 6 (Seg-6), associated with the eastern BTV topotype. However, based on Seg-1, -3, -4, -5, -7, -8, -9, and -10 analyses, the BTV-3/JJBB35 strain is more closely related to distinct BTV strains. These findings imply BTV circulation and that the Korean-isolated BTV might originate from Asian BTV strains due to multiple reassortment events. This study provides foundational data for ongoing BTV monitoring and disease-control policies in the ROK.

Biting midges of the genus Culicoides Latreille (Ceratopogonidae) pose a significant threat to veterinary health as vectors of over 60 viruses, most of which affect livestock. In this study, we used light traps to sample Culicoides populations on cattle and goat farms from May to October 2023 at 15 sites in Gyeongsangnam-do, Jeollanam-do, and Jeju Island, South Korea. Diversity and abundance were analysed based on the collection date, environmental conditions, and host species. A total of 124,055 individuals were collected, comprising 14 previously recorded and two newly recorded species: C. asiana and C. palawanensis . The dominant species was C. arakawae , which accounted for 80.60% of the total collected individuals, followed by C. punctatus (10.25%), and C. tainanus (3.36%), while the remaining 13 species constituted 5.80% of the collection. Total Culicoides abundance peaked in August (40.15%), driven largely by fluctuations in C. arakawae abundance, but the seasonal abundances of individual species varied. Culicoides arakawae and C. punctatus were dominant on the mainland, while C. matsuzawai , C. lungchiensis , and C. tainanus were dominant on Jeju Island. The dominant species on cattle farms were C. arakawae and C. punctatus, while C. arakawae dominated in collections from goat farms. The detection of two new species records suggests that the fauna of South Korea is still incompletely understood.

Hard ticks (Ixodidae family) are primary vectors of zoonotic diseases, including severe fever with thrombocytopenia syndrome (SFTSV), anaplasmosis, babesiosis, Lyme borreliosis, and ehrlichiosis. The roe deer (Capreolus pygargus tianschanicus), a key host for tick-borne diseases, is widely distributed on Jeju Island, Republic of Korea (ROK). Although the increased interactions between deer, livestock, and humans have raised concerns about zoonotic disease transmission, this area has remained understudied. Therefore, this study aimed to investigate the species diversity of ticks infesting roe deer and the prevalence of major tick-borne diseases in this region. From 2018 to 2020, 1832 ticks were collected from 154 roe deer. Four tick species were identified: Haemaphysalis longicornis (50.1 %), H. flava (47.9 %), Ixodes nipponensis (1.7 %), and H. megaspinosa (0.3 %). This study reports the first detection of H. megaspinosa in the ROK. Pathogen screening detected Anaplasma spp. (minimum infection rate, MIR: 0.38 %), Babesia spp. (0.05 %), and Ehrlichia spp. (0.44 %); however, sequencing was only successful for Anaplasma spp. These findings highlight the importance of continued tick surveillance and research on the zoonotic risks associated with emerging tick species in the ROK.