Avian influenza or Bird flu

Avian influenza or Bird flu


What is Bird flu

Bird flu is caused by a type of influenza virus that rarely infects humans. More than a dozen types of bird flu have been identified, including the two strains that have most recently infected humans H5N1 and H7N9. When bird flu does strike humans, it can be deadly.

In recent years, outbreaks of bird flu have occurred in Asia, Africa and parts of Europe. Most people who have developed symptoms of bird flu have had close contact with sick birds. In a few cases, bird flu has passed from one person to another.

Health officials worry that a global outbreak could occur if a bird flu virus mutates into a form that transmits more easily from person to person. Researchers are working on vaccines to help protect people from bird flu.

Bird Flu facts

  • Bird flu refers to strains of influenza that primarily affect wild and domesticated birds.
  • Bird flu is also known as avian flu or avian influenza.
  • Although bird flu is contagious and spreads easily among birds, it is uncommon for it to be transmitted to humans.
  • In the late 1990s, a new strain of bird flu arose which was unusually severe (“highly pathogenic”), resulting in the deaths of hundreds of millions of birds, including poultry.
  • Risk factors include association with birds and poultry farms and bird feces.
  • Symptoms include fever, cough, sore throat, nausea; symptoms often progress to severe breathing problems, pneumonia that can result in death.
  • Definitive diagnosis requires identification of the viral strain by immunological tests.
  • Treatment may include antiviral medication and often requires intensive supportive care.
  • Control efforts, including culling infected flocks and vaccinating healthy birds, have limited the spread of highly pathogenic bird flu strains.
  • In 2011, a mutated strain of highly pathogenic bird flu appeared, H5N1, which is concerning because the existing poultry vaccines are not very effective against the H5N1 strain; in 2013, a new strain, H7N9, appeared in China.
  • Human infection with highly pathogenic strains of bird flu is uncommon, with about 622 cases reported as of March 2013 since 1997.
  • Human infection occurs primarily in people who have close contact with sick poultry in countries where the virus is found; there have been isolated cases of human-to-human transmission.
  • There is no commercially available vaccine for humans against bird flu strains; human infection with bird flu is fatal in approximately 60% of infected humans, but only a small number of humans have become infected since 1997.
  • Bird flu from the highly pathogenic strains (for example H5N1) is not found in the United States at this time in birds or humans.

Bird Flu Symptoms

You may have H5N1 if you experience typical flu-like symptoms that may include:

  • cough
  • diarrhea
  • respiratory difficulties
  • fever (over 100.4°F)
  • headache
  • muscle aches
  • malaise
  • runny nose
  • sore throat

If you are exposed to bird flu you should notify healthcare providers before you arrive at the doctor’s office or hospital. Alerting staff ahead of time will allow them to take precautions to protect staff and other patients before caring for you.

Bird Flu Causes

Bird flu occurs naturally in wild waterfowl and can spread into domestic poultry, such as chickens, turkeys, ducks and geese. The disease is transmitted via contact with an infected bird’s feces, or secretions from its nose, mouth or eyes.

Open-air markets, where eggs and birds are sold in crowded and unsanitary conditions, are hotbeds of infection and can spread the disease into the wider community.

Undercooked poultry meat or eggs from infected birds can transmit bird flu. Poultry meat is safe to eat if it’s been cooked to an internal temperature of 165 F (74 C). Eggs should be cooked until the yolks and whites are firm.

What are Bird Flu Risk Factors?

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. The infection may be spread by touching contaminated surfaces.

You may have a greater risk of contracting H5N1 if you are:

  • a poultry farmer
  • a traveler visiting affected areas
  • exposed to infected birds
  • someone who eats undercooked poultry or eggs
  • a healthcare worker caring for infected patients
  • a household member of infected persons

Bird Flu Complications

People with bird flu may develop life-threatening complications, including:

  • Pneumonia
  • Collapsed lung
  • Respiratory failure
  • Kidney dysfunction
  • Heart problems

Although bird flu may kill more than half the people it infects, the number of fatalities is still low because so few people have had bird flu. Fewer than 500 bird flu deaths have been reported to the World Health Organization since 1997.

In contrast, the Centers for Disease Control and Prevention estimates that seasonal influenza is responsible for thousands of deaths each year in the United States alone.

What is the treatment for bird flu?

Because of the small number of human cases, it has not been possible to conduct rigorous treatment trials for bird flu. The current recommendation from the World Health Organization is to use an antiviral medication called oseltamivir (Tamiflu). In September 2011, the CDC stated the following: “Two other antiviral medications, oseltamivir and zanamivir (Relenza), would probably work to treat influenza caused by H5N1 virus, but additional studies still need to be done to demonstrate their effectiveness.” Patients often need intensive supportive care. It is too early to say if antivirals are effective against H7N9 bird flu.