The flu is a contagious respiratory illness caused by influenza type A or type B viruses. It can cause mild to severe illness and at times can be fatal. The best way to prevent this illness is by getting a flu vaccination (flu shot) each fall. Each year in the United States:
About 5% to 20% of the population gets the flu
More than 200,000 people are hospitalized with flu complications
About 36,000 people die from flu complications
Flu viruses spread in respiratory droplets caused by talking, coughing and sneezing that directly contact the nose, mouth or eyes. Large droplets can only travel a limited range (about 6 feet). The flu viruses usually spread from person-to-person, though sometimes people become infected by touching something with a flu virus on it and then touching their eyes, mouth or nose. Humans can infect others 1 day before symptoms develop and up to 5 days after becoming sick. That means that the flu can be passed on to someone else before you know you are sick, as well as while you are sick.
Avian influenza, otherwise known as birdflu, is an infection caused by avian (bird) influenza (flu) viruses. These influenza viruses occur naturally among birds. Wild birds worldwide carry the viruses in their intestines, but usually do not get sick from them. "Avian influenza virus" refers to influenza A viruses found chiefly in birds, but infections with these viruses can occur in humans. The risk from avian influenza is generally low to most people, because the viruses do not usually infect humans.
Human H5N1 influenza infection was first recognized in 1997 when this virus infected 18 people in Hong Kong, causing 6 deaths. According to WHO, confirmed cases of birdflu in humans have been reported in the following countries:
Lao People's Democratic Republic
Genetic studies confirm that the influenza A virus H5N1 mutates rapidly. Should it adapt to allow easy human-to-human transmission, a pandemic could ensue. The reported symptoms of avian influenza in humans have ranged from typical influenza-like symptoms (e.g. fever, cough, sore throat, and muscle aches) to eye infections (conjunctivitis), acute respiratory distress, viral pneumonia and other severe, life-threatening complications.
Most cases of avian influenza infection in humans have resulted from contact with infected poultry (e.g., domesticated chicken, ducks, and turkeys) or surfaces contaminated with secretion /excretions from infected birds. The spread of avian influenza viruses from one ill person to another has been reported very rarely, and has been limited, inefficient and unsustained. The World Health Organization (WHO) has registered 278 cases of birdflu in humans and 168 deaths. Highly pathogenic H5N1 is one of the few avian influenza viruses to have crossed the species barrier to infect humans and it is the most deadly of those that have crossed the barrier.