KEY FACTS:
Avian influenza (flu), often called “bird flu,” is an infection caused by an influenza virus that is usually specific to birds. This avian flu virus can infect many different species of birds. Some birds only carry the virus and it does not make them sick; in other birds, the virus causes a relatively minor illness that does not kill them. Rarely, the virus changes into a type that makes the birds very sick and can kill them. This type is called a “highly pathogenic avian flu.”
Usually, these viruses only infect birds; on rare occasions, they can jump species from birds to pigs, people or other animals. When this happens, the “bird flu” can make these animals sick, and, depending on the severity of the viral strain, it can kill the individual. In 1977, a type of deadly avian flu was discovered in Asia. This strain, known as H5N1, has spread across the globe and is expected to eventually reach North America. Worldwide, millions of birds have been infected with this new virus.
To date, about 200 people have also been infected with the H5N1 “bird flu” and about half have died; all the victims had direct contact with infected birds. There is no direct evidence that this virus has spread from person to person.
SYMPTOMS:
In domestic birds, infection with avian flu viruses causes two main forms of the disease that are characterized by low and high virulence. The least harmful bird flu may be undetectable and causes only mild symptoms, including ruffled feathers and a drop in egg production, according to the Centers for Disease Control and Prevention (CDC). However, the more harmful form of avian flu spreads more rapidly among poultry and may cause a disease that brings death, often within 48 hours.
In humans, symptoms of avian flu have ranged from typical flu-like symptoms, such as fever, cough and muscle aches, to eye infections, pneumonia and severe respiratory diseases. A laboratory test is needed to detect avian flu in humans.
PREVENTING AVIAN FLU:
There is no evidence to suggest that current strains of avian flu may be passed among humans, although in other countries there have been cases of humans contracting the disease directly from birds.
Two antiviral drugs—oseltamivir (Tamiflu) and zanamivir (Relenza) – significantly reduce symptoms of normal flu if taken within 24 to 48 hours and may be effective against bird flu. The Food and Drug Administration has not yet approved a vaccine against avian flu, but vaccines are currently being evaluated in clinical trials.
OTHER FEATURES:
Avian flu viruses do not usually infect humans, but about 200 confirmed cases of human infection with bird flu viruses have occurred since 1997. No cases of H5N1 avian flu have been reported in the United States among humans or birds. Human cases of avian flu infection have been reported in other countries, including Azerbaijan, Cambodia, China, Egypt, Indonesia, Iraq, Thailand, Turkey and Vietnam. There is concern that this new viral strain H5N1 could turn into a form that is both easily passed from person to person and may cause death. If that happens, then a severe pandemic is possible.
