According to the Centers for Disease Control and Prevention, five to twenty-five percent of all people in the United States get the flu every year. Flu outbreaks can have severe consequences. During 1918, the Spanish flu killed more than twenty million people all over the world.

What is the flu?

The flu, or influenza, starts with a virus that causes a respiratory illness. Flu symptoms include a high fever, chills, dry cough, sore throat, and muscle aches. Complications can occur because your immune system may be run down by the virus, allowing secondary bacterial infections to cause illnesses such as bacterial pneumonia. The flu can make diabetes, heart failure, and asthma worse. Young children and the elderly are particularly susceptible to flu and resulting complications. Flu season in the United States lasts from roughly October to May.

Transmission

Influenza can be transmitted through the air by coughing and sneezing. It can also be caught through touch. If you touch the droplets from a sneeze or a cough that have landed on a table or a telephone and then touch your eyes, mouth, or nose, you may get the flu virus. It is important to note that you can pass the virus on to someone else before you actually start to feel any flu symptoms.

Prevention

There are simple means of helping to prevent getting the flu and helping to prevent spreading the flu if you come down with it. Always cover your mouth when you sneeze or cough. This will help keep airborne transmission of the flu virus down. Wash your hands frequently. Try to remember not to touch your eyes, mouth, or nose. If you are sick with the flu, do not push it. Stay home.

H5N1 is an avian influenza virus. It is a pandemic threat. H5N1 is what is commonly meant when talking of "bird flu" or "avian influenza". It is a viral disease that causes illness in many species including humans.

H5N1is moving from areas where it is endemic to other parts of the world through migrating waterfowl who can carry and spread H5N1 (sometimes without themselves becoming sick).[1] Humans who get sick from H5N1 typically catch it from chickens who catch it from either other chickens or waterfowl (ducks and geese). H5N1 is mutating into genetic variations that are infecting species not previously known to carry H5N1, but not all of these variations can infect humans.

It is endemic in birds in southeast Asia and is threatening to become endemic in birds in Turkey. Current evidence from the latest outbreaks in north, central and east Turkey show a hemagglutinin mutation making H5N1 easier to pass from chickens to humans, but not yet easier to pass from human to human[2]. Species killed by H5N1 infection in this December 2005 and January 2006 outbreak in Turkey include humans, chickens, turkeys, ducks, geese, and pigeons[3].

As of January 11, 2006, 155 cases of infections in humans, resulting in 78 deaths, have been confirmed worldwide. Not all cases of H5N1 infection are reported and consequently the exact mortality rate is unknown. Earlier historical flu pandemics, which were also believed to be of avian origin, had reportedly an average mortality rate of 2.5-5%. Thirteen countries across Asia and Europe have been affected. Tens of millions of birds died of H5N1 influenza and hundreds of millions of birds were culled (slaughtered and disposed of) to protect humans from H5N1[2].
The current projected worst case scenario for a H5N1 pandemic is somewhere around 150,000,000 human deaths directly due to H5N1 infection (or two to three percent of the world's human population). No one knows what the chances are for this worst case scenario.

Cumulative number of confirmed human cases of H5N1 avian influenza infection - Taken from WHO site January 14, 2006