Avian influenza viruses can be transmitted directly from wild birds to domestic poultry or indirectly e. The virus spreads directly from bird to bird via airborne transmission or indirectly, through faecal contamination of material, feathers or feed. Large amounts of virus are secreted in bird droppings, contaminating soil and water supply. Contaminated equipment, vehicles, feed, cages or clothing - especially shoes - can spread the virus in between farms.
The possibility of spread of contaminated dust particles via wind from one farm to another, in close proximity, is discussed. The virus can also be mechanically carried by other animals, such as rodents.
Humans are usually infected through close contact with infected birds, bodily fluid droplets such as those generated during defeathering processes, or other contaminated material. Birds shed influenza virus in their faeces and therefore contact with bird droppings is also a possible transmission route. Avian flu virus is killed by heat and common disinfectants. Heat treatment such as cooking will destroy the virus.
Most avian influenza viruses do not cause disease in humans, or cause only mild illness, such as fever or conjunctivitis. The best protective measure is to avoid direct contact with dead and potentially infected wild birds or poultry.
Visits to live bird markets and similar places with large concentrations of birds should be avoided, especially in affected areas. If occupationally exposed, personal protective equipment should be used to minimise direct exposure.
Antiviral drugs such as oseltamivir and zanamivir are considered effective against several avian influenza viruses. There is no single vaccine against avian influenza. A specific vaccine is needed for each specific avian influenza strain, and they need to be adapted as the virus continues to change.
According to the World Health Organization , H5N1 was first discovered in humans in and has killed nearly 60 percent of those infected.
Still, some experts worry that H5N1 may pose a risk of becoming a pandemic threat to humans. Alerting them ahead of time will allow them to take precautions to protect staff and other patients before caring for you. Although there are several types of bird flu, H5N1 was the first avian influenza virus to infect humans. The first infection occurred in Hong Kong in The outbreak was linked to handling infected poultry. H5N1 occurs naturally in wild waterfowl, but it can spread easily to domestic poultry.
The disease is transmitted to humans through contact with infected bird feces, nasal secretions, or secretions from the mouth or eyes. H5N1 has the ability to survive for extended periods of time.
Birds infected with H5N1 continue to release the virus in feces and saliva for as long as 10 days. Touching contaminated surfaces can spread the infection. It can offer preliminary results in only four hours. Your doctor may also perform the following tests to look for the presence of the virus that causes bird flu:.
In most cases, treatment with antiviral medication such as oseltamivir Tamiflu or zanamivir Relenza can help reduce the severity of the disease. However, the medication must be taken within 48 hours after symptoms first appear. The virus that causes the human form of the flu can develop resistance to the two most common forms of antiviral medications, amantadine and rimantadine Flumadine. The outlook for bird flu infection depends on the severity of infection and the type of influenza virus causing it.
Call your doctor if you have flu symptoms within 10 days of handling birds or traveling to areas with a known avian flu outbreak. If you develop both the avian flu and human flu at the same time, it could create a new and possibly deadly form of the flu.
However, you can minimize your risk by avoiding:. Sometimes it may still be possible to diagnose avian influenza A virus infection by looking for evidence of antibodies the body has produced in response to the virus. This is not always an option because it requires two blood specimens one taken during the first week of illness and another taken weeks later.
Also, it can take several weeks to verify the results, and testing must be performed in a special laboratory, such as at CDC. CDC has posted guidance for clinicians and public health professionals in the United States on appropriate testing, specimen collection and processing of samples from patients who may be infected with avian influenza A viruses.
CDC currently recommends a neuraminidase inhibitor for treatment of human infection with avian influenza A viruses. CDC has posted avian influenza guidance for health care professionals and laboratorians , including guidance on the use of antiviral medications for the treatment of human infections with novel influenza viruses associated with severe disease. Analyses of available avian influenza viruses circulating worldwide suggest that most viruses are susceptible to oseltamivir, peramivir, and zanamivir.
However, some evidence of antiviral resistance has been reported in Asian H5N1 and Asian H7N9 viruses isolated from some human cases. Monitoring for antiviral resistance among avian influenza A viruses is crucial and ongoing. The best way to prevent infection with avian influenza A viruses is to avoid sources of exposure. Most human infections with avian influenza A viruses have occurred following direct or close contact with infected poultry. People who have had contact with infected birds may be given influenza antiviral drugs preventatively.
While antiviral drugs are most often used to treat influenza, they also can be used to prevent infection in someone who has been exposed to influenza viruses. CDC has posted interim guidance for clinicians and public health professionals in the United States regarding follow-up and influenza antiviral chemoprophylaxis of persons exposed to birds infected with avian influenza A viruses.
Seasonal influenza vaccination will not prevent infection with avian influenza A viruses, but can reduce the risk of co-infection with human and avian influenza A viruses.
For example, the United States government maintains a stockpile of vaccines to protect against some Asian avian influenza A H5N1 viruses. The stockpiled vaccine could be used if similar H5N1 viruses were to begin transmitting easily from person to person.
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