Prevalence and Genotypic Distribution of Bovine Leukemia Virus across Asian Regions: Insights into Economic Significance and Clinical Staging

This study critically reviews the literature on the prevalence and genotypic distribution of Bovine Leukemia Virus (BLV) in Asia, specifically targeting enzootic bovine leukosis, a chronic disease affecting cattle’s life and milk production along with reduced fat yield, that causing economic losses due to increased susceptibility to pathogens. European countries are eradicating BLV but Asia has a high prevalence, particularly in Asian cattle. Enzootic bovine leukosis (EBL) has distinct clinical stages: asymptomatic, persistent lymphocytosis, and lymphosarcoma. It typically occurs in adult animals, with 60% being asymptomatic during the aleukemic stage, 30% developing persistent lymphocytosis, and 5% developing lymphoma. Databases like PubMed and Google Scholar were used to search molecular and prevalence studies from 2000-2024, focusing on Asian countries. Prevalence of bovine leukosis (BL) in Asia varies significantly, with high rates in central and eastern regions. BLV is a global disease, has increased in Asia with highest prevalence in central Asia about 40.0–84.0% (Kazakhstan), 35% in Eastern Asia (Japan), and 58.3% in Southeast Asia (Thailand). BLV genotypes G1, G4, G6, G7, G12, G3, G4, G6, G7, and G10 are prevalent in various regions of Asia, with G1 being most prevalent globally. These genotypes might be spread due to animal trading, and animal domestication, affecting various countries. This review provides the current status of enzootic bovine leukosis in Asia, emphasising the need for a closed trading system to control the disease.