Virus Home > How Does Bird Flu Spread?
Many people ask, "How does bird flu spread?" Bird flu spreads when infected birds shed the virus in their secretions and feces. Although bird flu viruses do not usually infect humans, 100 confirmed cases have occurred since 1997. The spread of bird flu viruses from an ill person to another person is rare, and transmission has not been observed to continue beyond one person.
Bird flu is a type of flu normally found in birds. Infected birds shed influenza virus in their saliva, nasal secretions, and feces. Susceptible birds become infected when they have contact with contaminated excretions or with surfaces that are contaminated with excretions or secretions. Domesticated birds may become infected with avian influenza virus through:
- Direct contact with infected waterfowl or other infected poultry
- Contact with surfaces (such as dirt or cages)
- Materials (such as water or feed) that have been contaminated with the virus.
Although bird flu viruses do not usually infect humans, more than 100 confirmed cases of human infection with bird flu viruses have occurred since 1997. Most cases of bird flu infection in humans have resulted from direct or close contact with infected poultry (domesticated chickens, ducks, and turkeys) or with surfaces contaminated with secretions and excretions from infected birds. The spread of bird flu viruses from an ill person to another person has been reported only rarely, and transmission has not been observed to continue beyond one person.
Most cases of bird flu spread in humans are the result of direct or close contact with infected poultry or with surfaces contaminated by the secretions and excretions from infected birds. As mentioned, the spread of bird flu viruses from an ill person to a healthy person has rarely been reported. Furthermore, it isn't believed that the virus can continue beyond one person. However, the greater concern with bird flu is that, given enough opportunities, the bird flu will change (mutate) into a form that is highly infectious for humans and that spreads easily from person to person. If this happens, a pandemic flu outbreak would occur.
(Click Avian Flu for more information about bird flu and why it is a concern for humans.)