Avian influenza in birds: Insights from a comprehensive review

One of the worst zoonotic illnesses, avian influenza (AI), or commonly referred to as bird flu, is caused by viruses belonging to the genus Influenza viruses, which are members of the Orthomyxoviridae family. The harmful effects of AI illness can affect both human and animal health and cause financial losses. Globally, the AI virus lacks political purpose and is not limited by geographical limits. It has been isolated from poultry, wild birds, and captive birds in Asia, North America, Europe, Australia, and South America. Their virulence is divided into highly pathogenic AI (HPAI) and low pathogenic AI (LPAI). The AI virus can also be diagnosed in a laboratory setting using molecular tests like real-time polymerase chain reaction or serological tests like the hemagglutinin inhibition test, agar gel immunodiffusion, antigen detection enzyme-linked immunosorbent assay, and other immunoassays. The type of AI virus and host species determines the clinical manifestations, severity, and fatality rates of AI. Human infection with AI viruses typically results from direct transmission from infected birds to humans. AI outbreaks in domestic and wild birds are uncommon; however, an infection can pose a significant threat to public, veterinary, and medical health. Successful vaccination reduces the probability of AI H5N1 virus infection in meat and other poultry products and prevents systemic infection in chickens. This review will provide information that can be used as a reference for recognizing the dangers of AI and for preventing and controlling the disease, considering its potential to become a serious pandemic outbreak.