Avian (bird) influenza (flu) refers to a large group of different influenza viruses that primarily affect birds. Bird flu viruses occur naturally among birds in the wild. Wild birds worldwide carry the viruses in their intestines, but usually do not get sick from them. However, bird flu is very contagious among birds and can make some domesticated birds, including chickens, ducks, and turkeys, very sick and kill them. Infected birds shed flu virus in their saliva, nasal secretions, and feces. Susceptible birds become infected when they have contact with contaminated excretions.
On rare occasions, these bird viruses can infect other species, including pigs and humans. The vast majority of avian influenza viruses do not infect humans. However, it is believed that most cases of bird flu infections in humans reported since 1997 have resulted from close contact with infected poultry or contaminated surfaces.
Health experts have been monitoring a new and extremely severe influenza virus - the H5N1 strain - for almost eight years. The H5N1 strain first infected humans in Hong Kong in 1997, causing 18 cases, including six deaths. Since mid-2003, this virus has caused the largest and most severe outbreaks in poultry on record in Asia and parts of Europe. In December 2003, infections in people exposed to sick birds were identified.
For this reason, avian influenza, H5N1, is a strain with pandemic potential. It might ultimately adapt and mutate into a strain that is contagious among humans, thus possessing the ability to spread from person to person. A pandemic occurs when a new influenza virus emerges and starts spreading as easily as normal influenza - by coughing and sneezing. Because the virus is new, the human immune system will have no pre-existing immunity. This makes it likely that people who contract pandemic influenza will experience more serious disease than that caused by normal influenza. Once this adaptation occurs, it will no longer be a bird virus--it will be a human influenza virus. An influenza pandemic is a rare but recurrent event. Fortunately, the virus does not jump easily from birds to humans or spread readily and sustainably among humans.
There currently is no commercially available vaccine to protect humans against the H5N1 virus that is being seen in Asia and Europe. However, vaccine development efforts are taking place. Research studies to test a vaccine to protect humans against H5N1 virus began in April 2005, and a series of clinical trials is underway.
Federal, state and local public health have been working together to prepare for a possible influenza pandemic. Because public health often deals with re-emerging or new diseases such as SARS, many of these functions are already in place. Local and state response will likely hinge on resources available at the federal level. The CDC is doing a "full-court press" in preparing for an eventual pandemic; a national strategy for pandemic influenza was released in November of 2005. The Fulton County Health Department wrote a pandemic influenza plan in 2004. Revisions to the Fulton County Plan are occurring based upon new information as it is made available.
Links:
US Government/Avian & Pandemic Flu Information
Ohio Pandemic Flu