Pandemic Influenza

A pandemic is a global disease outbreak. A flu pandemic occurs when a new influenza virus emerges for which people have little or no immunity, and for which there is no vaccine. The disease spreads easily person-to-person, causes serious illness, and can sweep across the country and around the world in very short time.

It is difficult to predict when the next influenza pandemic will occur or how severe it will be. Wherever and whenever a pandemic starts, everyone around the world is at risk. Countries might, through measures such as border closures and travel restrictions, delay arrival of the virus, but cannot stop it.

Pandemics occurred three times in the past century. The most recent (1968) was the mildest and killed about 34,000 people in the United States. The most severe influenza pandemic in the past century occurred in 1918 and killed about 500,000 Americans and up to 40 million people worldwide.

Health professionals are concerned that the continued spread of a highly pathogenic avian H5N1 virus across eastern Asia and other countries represents a significant threat to human health. The H5N1 virus has raised concerns about a potential human pandemic because:

• It is especially virulent
• It is being spread by migratory birds
• It can be transmitted from birds to mammals and in some limited circumstances to humans, and
• Like other influenza viruses, it continues to evolve.

Since 2003, a growing number of human H5N1 cases have been reported in Azerbaijan, Cambodia, China, Egypt, Indonesia, Iraq, Thailand, Turkey, and Vietnam. More than half of the people infected with the H5N1 virus have died. Most of these cases are all believed to have been caused by exposure to infected poultry. There has been no sustained human-to-human transmission of the disease, but the concern is that H5N1 will evolve into a virus capable of human-to-human transmission.

AVIAN INFLUENZA

Avian (bird) flu is caused by influenza "A" viruses that occur naturally among birds. There are different subtypes of these viruses because of changes in certain proteins (hemagglutinin [HA] and neuraminidase [NA]) on the surface of the influenza "A" virus and the way the proteins combine.

Each combination represents a different subtype. All known subtypes of influenza "A" viruses can be found in birds. The avian flu currently of concern is the H5N1 subtype.

Wild birds worldwide carry avian influenza viruses in their intestines, but usually do not get sick from them. Avian influenza is very contagious among birds and can make some domesticated birds, including chickens, ducks, and turkeys, very sick and kill them.

Infected birds shed influenza virus in their saliva, nasal secretions, and feces. Domesticated birds may become infected with avian influenza virus through direct contact with infected waterfowl or other infected poultry, or through contact with surfaces (such as dirt or cages) or materials (such as water or feed) that have been contaminated with the virus.

Avian influenza infection in domestic poultry causes two main forms of disease that are distinguished by low and high extremes of virulence. The "low pathogenic" form may go undetected and usually causes only mild symptoms (such as ruffled feathers and a drop in egg production). However, the highly pathogenic form spreads more rapidly through flocks of poultry. This form may cause disease that affects multiple internal organs and has a mortality rate that can reach 90-100%, often within 48 hours. The H5N1 virus is highly pathogenic.

SOCIAL DISRUPTION

1. Plan for the possibility that usual services may be disrupted. These could include services provided by hospitals and other health care facilities, banks, stores, restaurants, and government services.
2. Prepare backup plans in case public gatherings, such as volunteer meetings and worship services, are canceled.
3. Consider how to care for people with special needs in case the services they rely on are not available.
4. Plan for the possible reduction or loss of income if you are unable to work or your place of employment is closed.
5. Stock a supply of water, food, and supplies. During a pandemic you may not be able to get to a store, stores may be depleted, and/or public waterworks services may also be interrupted.

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