Diagnosis of the first confirmed case of African swine fever in Taiwan
Jen-Chieh Chang
Abstract
African swine fever (ASF) is a highly lethal infectious disease of pigs and transboundary transmitted globally. In October 2025, a commercial pig farm in Taichung, Taiwan, experienced a sudden outbreak with extensive pig mortality within a short period of time, resulting in a cumulative mortality rate exceeding 37.5%. Affected animals exhibited clinical signs including respiratory distress, sudden death, and nasal hemorrhage. Gross pathological examinations revealed prominent hemorrhagic lesions in the skin, kidneys, and various lymphoid tissues, as well as splenomegaly. The samples from suspected cases were submitted to the Veterinary Research Institute, Ministry of Agriculture, for laboratory analysis. Diagnostic testing was conducted in accordance with the African swine fever diagnostic methods recommended in the World Organisation for Animal Health (WOAH) Terrestrial Manual. Molecular analyses confirmed that multiple tissue samples tested positive for the African swine fever virus (ASFV) using both real-time PCR and conventional PCR methods. Virus isolation was successfully achieved, and typical positive reactions were observed in the hemadsorption (HAD) test, followed by genetic sequencing and comparative analysis. To support the clinical and molecular findings, histopathological examinations were conducted, revealing hemorrhagic and/or necrotizing lesions in the spleen, lymph nodes, and kidneys. Immunohistochemical staining further indicated the presence of ASFV antigens in selected tissues. However, the pathological and immunolabeling findings were considered supportive evidence and do not constitute mandatory confirmatory methods according to WOAH standards. The integration of viral genome detection, virus isolation, and other diagnostic techniques confirmed that this case met the WOAH criteria for African swine fever confirmation, marking it as the first confirmed case of ASF in Taiwan.
Current Status of Avian Influenza Virus Surveillance in Taiwan: Peripheral Environmental Investigation of Poultry Farms and Genomic Analysis of Highly Pathogenic Viruses
Li-Hsuan Chen
Abstract
Clade 2.3.4.4 H5 subtype high pathogenicity avian influenza (HPAI) viruses have continued to spread globally since 2014. In recent years, driven by virus carriage in wild birds and frequent reassortment events, outbreaks have been reported on all continents except Australia. In Taiwan, clade 2.3.4.4c H5N2, H5N3, and H5N8 viruses were introduced at the beginning of 2015, followed by the detection of clade 2.3.4.4b H5N2 viruses in 2021 and the incursion of clade 2.3.4.4b H5N1 viruses in November 2022. By 2023, the latter had replaced the previous circulating strains and has remained the predominant lineage in poultry farms to date. Under conditions of frequent poultry movement, diverse farming systems, and a high seroprevalence background, viral transmission and evolutionary trajectories have become increasingly complex. The 2025 research program comprised peripheral environmental surveillance of poultry farms and viral genomic analysis. In the fourth quarter of 2025, environmental sampling conducted on 255 poultry farms were completed, with nine positive detections (3.5%), and the highest risk was found in waterfowl farm; furthermore, an H6N1 virus was also successfully detected in a layer farm, demonstrating the early warning capacity of this surveillance system. In parallel, the project of next-generation sequencing was performed on 44 avian influenza viruses, confirming the continued circulation of multiple H5N1 genotypes in Taiwan. The phylogenetic relationships and key biomarkers associated with cross-species transmission were analyzed. Overall, these results reveal that the integration of environmental surveillance with high-resolution genomic analysis facilitates monitoring of viral evolutionary trends, assessment of interspecies transmission risk, and providing a scientific basis for subsequent prevention strategies and poultry industry–wide surveillance.
Attended the 1st Roundtable Meeting of East Asian National Animal Health Institutes held in Japan
Fang Yu, Hsu
Abstract
The 1st Roundtable Meeting of East Asian National Animal Health Institutes was held in Tsukuba, Japan, providing a valuable platform for scientific exchange and regional collaboration in the field of animal health. The meeting focused on transboundary animal diseases, with particular emphasis on high pathogenicity avian influenza (HPAI), African swine fever (ASF), and classical swine fever (CSF). Case studies from participating countries highlighted that HPAI viruses continue to pose a significant threat to the poultry industry, due to dissemination by migratory birds and continued genetic reassortment. Although CSF has been successfully eradicated in some countries, but re-emergence has occurred due to the establishment of wildlife reservoirs, indicating the need for integrated vaccination strategies and long-term surveillance. ASF remains a major concern in the region, driven by illegal cross-border movement of contaminated pork products and transmission via wild boar populations. The discussions underscored the critical importance of international cooperation in managing transboundary animal diseases. For Taiwan, continued strengthening of interagency surveillance, biosecurity management, and border quarantine measures is essential. In addition, adopting lessons learned from other countries and integrating advanced technological tools into disease prevention strategies will be key to enhancing preparedness and response capacity. Expanding and sustaining international collaboration will further contribute to improving Taiwan’s ability to prevent and control transboundary animal diseases.