Avian Influenza

Bird Flu – Introduction and Background

Barraged by sensationalism in the press balanced by healthy respect for nature’s potential ravages, we have noted increased inquiry regarding “bird flu” from many of our clients. Armed with the facts, it is easier to put the risk of infection in proper perspective.

Avian influenza (bird flu) generally refers to a family of viruses that wild birds tend to carry in their intestines usually without being sick. The virus can be spread to and become highly contagious to domestic birds resulting in significant poultry losses. Fortunately, it is rather rare for the virus to “jump species” and there are relatively few recorded cases of human infection to date, and almost no human to human spread.

Flu viruses are classified by types and subtypes. The type A flu is distinguished by surface proteins such as hemagglutinin (HA) of which there are 16 different subtypes and neuraminidase (NA) with 9 different subtypes. Many different combinations of HA and NA are possible in birds, but typically only H1N1, H1N2, and H3N2 are ever found in humans. Unfortunately, flu A viruses are constantly changing or mutating and that has driven the fear that in conditions of large poultry outbreaks in close proximity to humans, the greater the likelihood of a mutated subtype to “jump species”. If the mutated subtype was easily transmitted from human to human, there would be very little native immunity allowing the potential for a worldwide pandemic such as that which occurred during the 1918 Spanish flu which killed 500,000 Americans and some 50 million people worldwide. In fact there have been three such pandemics in the last 100 years. One plan shows potential for up to 1.9 million deaths in the U.S. if such a pandemic were to occur.

Symptoms and Treatment

Bird flu just like typical influenza in humans results in fever, cough, sore throat, muscle aches, eye infections, pneumonia, severe respiratory disease, and other potentially life threatening complications. However, in the few cases of actual human infection with avian flu subtype (H5N1), first isolated from terns in South Africa in 1961, the death rate has been reported as high as 50 percent. As of the time this article is written, H5N1 virus has infected 124 people in Thailand, Vietnam, Cambodia and Indonesia since 2004, killing 63 of them. Most of the exposures to H5N1 have involved contact with infected poultry, bird droppings, or contaminated surfaces, and there have been no documented cases of sustained human to human spread.

Evidence exists that the H5N1 strain may be somewhat susceptible to currently available commercial antiviral medications such as oseltamavir or Tamiflu. A vaccine that is also effective against this avian flu strain was developed and in 2013 the FDA approved a modified vaccine to supplement the National Stockpile for emergent pandemic use rather than routine commercial availability. The reality is that one’s chances are exponentially more likely to become infected with typical human influenza. That vaccine is currently available.

What You Should Know (Prevention)

For those wanting to minimize chances of infection with influenza:

  • Hand washing – The first line of defense is careful hand hygiene
  • Cover your cough – Preventing the aerosolization of virus laden water particles
  • Dispose of used tissues in a waste basket
  • Avoid traveling when ill
  • Consider vaccination especially if your physician feels you are at higher risk

Additionally if you are a traveler to Asian countries experiencing outbreaks of avian influenza:

  • Avoid poultry farms
  • Avoid contact with birds
  • Avoid contact with surfaces contaminated with bird droppings
  • Tell healthcare providers in advance if you suspect exposure so consideration can be made to minimize theoretical transmission to others
  • Airlines entering the US are now required by law to report suspicious illness to US Quarantine Stations
  • When flying, ill passengers should be kept at least 3-6 feet from others when possible and provided masks or tissues to cover their cough

Conclusion and References

By and large, it is obvious that the average individual has very little cause for concern over bird flu at the present time, and as noted good hand washing hygiene is always a good idea. Should you have any questions regarding this or any traveler’s health issue, feel free to contact the AMAS physician staff.