An outbreak of bird flu, technically known as avian influenza, has hit several Asian countries in recent months. Avian influenza is caused by type A strains of the influenza virus, it was first identified in Italy more than 100 years ago. Migratory waterfowl (usually ducks) are the natural reservoir of avian influenza viruses. The A (H5N1) strain of influenza is resistant to the common anti-influenza drugs, amantadine and rimantadine. There is massive slaughter of chickens underway to stop the spread of the virus.
The H and N denote two proteins, hemagglutinin and neuraminidase, that sit on the outer shell of the virus. Together, they provide a virus's chemical appearance to the immune system. The particular combination of H and N is the key to a strain's identity and the first hint of whether it might be a danger to people. Outbreaks of the highly pathogenic form have been caused by influenza A viruses of subtypes H5 and H7.
H5N1 can cause severe disease in humans. To date, all the human victims contracted the disease from fowl. Officials worry that the A (H5N1) bird flu, could combine with a human influenza virus to create a new strain which could be transmitted person-to-person. That strain could cause an epidemic in people.
The A (H5N1) strain was first detected in 1997 in Hong Kong, after it passed through geese and chickens infecting people. Until then, experts believed that avian influenza viruses had to pass through pigs before becoming a danger to humans.
The end of January, international health and food safety agencies began appealing to donors for funds and technical assistance to help stop the spread of bird flu in Asia. As of 1/27/04, ten countries have reported bird flu (Cambodia, Indonesia, Japan, Pakistan, South Korea, Taiwan, Thailand, Vietnam, Laos and China). The World Health Organization believes the near-simultaneous outbreaks are historically unprecedented.
There are fears that the bird flu virus could mutate, attaching itself to a human flu virus, which could spread between people, creating a global epidemic. In the 20th century, the great influenza pandemic of 1918–1919 which caused an estimated 40 to 50 million deaths worldwide, is thought to have been the result of influenza A.
In 1999, WHO instituted an influenza pandemic preparedness plan that set out a series of steps to be taken following confirmation of a human infection with a new subtype not yet spreading from person-to-person. As a precautionary measure, WHO is moving forward with the procedures needed to rapidly produce a new influenza vaccine capable of protecting humans against avian A (H5N1).
More Information
CDC- Avian Influenza
WHO- Avian Influenza
