The emerging tick-borne Yezo virus - current knowledge, challenges, and perspectives

Ticks are external parasites that can carry and transmit a diverse range of pathogens, including bacteria, parasites, and viruses. In recent years, factors such as climate change, deforestation, and human activities have contributed to the expansion of tick populations along with the pathogens they harbour. These pathogens can cause serious disease in both humans and animals, such as Lyme disease and Crimean Congo Hemorrhagic Virus (CCHFV). In 2021, a novel tick-borne orthonairovirus, Yezo virus (YEZV) was reported in Hokkaido, Japan, in two patients presenting with acute febrile illness characterized by thrombocytopenia and leukopenia. Subsequent cases of YEZV have been reported in China, and it has been isolated in ticks collected from migratory birds in Japan, indicating its potential to spread further. As this virus emerges, critical gaps remain in understanding the mechanisms of YEZV pathogenesis, transmission, and prevention. This review aims to provide a comprehensive understanding of YEZV since its discovery, with a focus on its biology, pathogenesis, reported patient cases, treatments, and prevention strategies. By examining the current literature, this review seeks to identify key directions for future research and public health initiatives to enhance control measures for this emerging disease. Ultimately, adopting cross-sectoral One Health approaches will improve early warning, prevention, and preparedness for a potential global health emergency caused by YEZV.