Bird Flu Basics
Avian Influenza (Bird Flu)

Avian influenza is an infection that occurs naturally among birds. Wild birds carry the viruses in their intestines but do not get sick from them. However, bird flu is very contagious among birds, and domesticated birds, including ducks, chickens, and turkeys, are particularly susceptible to these viruses.

Domesticated birds might become infected with the bird flu through direct contact with waterfowl or other infected birds. They might also become infected through contact with dirt, cages, water, or feed that have been contaminated with the virus.

Infection with the bird flu virus among domestic poultry causes two main forms of the disease. The low pathogenic form causes only mild symptoms and may go undetected. The high pathogenic form, on the other hand, spreads rapidly through flocks and may cause disease that affects the function of multiple internal organs. This form of infection might have a mortality rate that reaches 100% within 48 hours.

Bird flu viruses that affect Humans

Type A influenza viruses contain many different sybtypes. These subtypes vary according to the two forms of proteins found on the surface of the virus—hemagglutinin and neurominidase (H and N). There are sixteen known H sybtypes and nine known N subtypes. Combinations of these different types comprise different subtypes of the type A virus.
The avian influenza virus usually refers to viruses found only in birds. However, infections with these viruses can occur in humans. Many cases of avian influenza infection have resulted from exposure to infected poultry or surfaces contaminated by secretions from infected birds. The spread of bird flu virus from one person to another is rare.
Symptoms of avian influenza in humans range from common flu symptoms such as fever, cough, and sore throat, to eye infections, severe respiratory diseases, and life-threatening complications.

Human health risks during the bird flu outbreak

The H5N1 virus has caused the largest number of severe disease and death in humans among the few avian influenza viruses that have crossed the species barrier.
More than half of the people reported infected with the ongoing H5N1 outbreaks have died. Most cases have occurred in previously healthy young children and adults and have resulted from contact with contaminated surfaces.

Although there has been some human-to-human spread with H5N1, it has been limited and short-lived. Reports of human-to-human infection occur within family members only; cases of infection outside of people living in close quarters with the infected patient are nonexistent as far as people can tell. 

However, viruses tend to mutate, and scientists have voiced concerns that the H5N1 virus could change to transmit itself more easily from person to person. There is little to no immune protection against these viruses since they usually affect birds only.
Although there are no vaccines for the bird flu at the moment, scientists are working to create vaccines to help better prepare people for the imminent threat of a bird flu epidemic.