What Is Bird Flu? Bird flu is the disease caused by the viral infection with avian (bird) influenza (flu) viruses. These viruses occur naturally among wild aquatic birds worldwide. They carry the viruses in their intestines and respiratory tract and usually do not get sick from them. However, bird flu is very contagious among birds and can possibly sicken or kill domesticated birds such as chickens, ducks and turkeys. Which Virus Causes Bird Flu? There are four types of influenza virus: A, B, C and D. The virus that causes bird flu is influenza A. These viruses are categorized based on their genetic […]