Avian viruses are pathogens that primarily infect birds, causing various diseases. These viruses can affect both wild and domesticated bird species, leading to symptoms ranging from mild respiratory issues to severe illnesses. Some well-known avian viruses include avian influenza and Newcastle disease virus, which can have significant impacts on poultry health and the poultry industry. Transmission of avian viruses often occurs through direct contact between infected and healthy birds, contaminated environments, or through vectors like mosquitoes. Control measures, such as vaccination and biosecurity practices, are essential to prevent outbreaks and protect both bird populations and human health, as some avian viruses can potentially infect humans.