Influenza A is a virus that has many different strains. Some strains affect people and cause the flu illness that we experience each winter. Many influenza A viruses occur naturally in wild birds, primarily shore birds and waterfowl and are known as avian influenza or "bird flu". Most strains of avian influenza cause little or no disease in wild birds and poultry. Some strains can cause severe disease in poultry. One such strain, known as H5N1, originated in Asia in 1996 and has caused outbreaks in domestic poultry throughout Asia, Europe and Africa.
Avian influenza strains can also cause illness in people. Depending upon the strain of virus, human disease can range from very mild disease to severe respiratory disease with high mortality. To date, human infection with avian influenza strains has not been common. Most people who have become sick from avian influenza have been those with close contact with infected poultry. Person-to-person transmission occurs rarely, if at all. As of July 25, 2007, 319 human cases and 192 deaths have been attributed to H5N1 avian influenza infection. Humans can become infected with avian influenza primarily through contact with infected poultry (dead or alive) or with dust or soil contaminated with respiratory secretions or feces from these birds.
Influenza A viruses easily mutate, and can undergo major genetic changes. When people are infected with both human and avian influenza strains the viruses can trade genetic material, which can result in a strain that causes severe human illness and is easily transmitted from person-to-person. This could result in a worldwide influenza outbreak among humans also called a pandemic. Because humans have been infected with H5N1 avian influenza there is concern that conditions are right for creating a strain capable of causing a worldwide outbreak among humans. To date, there have been no reports of H5N1 in birds or humans in North America.
Current efforts are focused on preventing entry of the virus into the United States through human travel and illegal transportation of infected birds and equipment. State and federal wildlife officials are developing surveillance methods for detection of the virus in migratory birds. State and federal officials have plans in place to detect and contain avian influenza should it be introduced into U.S. poultry. In Oregon, state public health is collaborating with these agencies regarding the human health issues associated with these efforts.
Reporting Sick and Dead Birds
Guidelines for Human Testing
Avian Influenza Resources