The current H5N1 avian flu strain spreads primarily via the GI tract. This is why is doesn't spread efficiently person to person. People who come into close contact with chickens and their "dropping" are at the greatest risk to contract the disease. After contracting the virus, the immune system "overreacts" to the virus which result in multi-organ failure. While seasonal flu targets infants and the elderly with weak immune systems, pandemic flu kills healthy young people with strong immunity.
Researchers are currently studying the evolution of H5N1 avian flu to see what changes are necessary to cause it to be efficently spread human to human. Studying the latest cases in Turkey show that these changes are happening before our eyes. First the virus is obtaining mutations which allow it to replicate at cooler temperatures, such as those found in the human respiratory tract. Sequence of virus isolated from victims in Turkey also show new mutations which allow more efficent binding of the virus to cell receptors in lung tissue. It is this conversion from GI to respiratory that will allow efficent human to humanspread. The flu virus will increase in communicability by specializing on attacking lung tissue and then be transmissible by droplet rather than by fecal-oral route. Other similar mutations will result in the impending pandemic.
When this specialization occurs, the virus will cause overwelming damage to lung tissue. Victims will suffer respiratory failure and require mechanical ventillation or die. Even with mechanical ventillation, victims will develop ARDS (acute respiratory distress syndrome). No one really understands the cause of this syndrome. But we do know that 50% of ARDS patients die inspite of being on a vent. Without mechanical ventillation, death rates will be far worse. In spite of the perfect cell-based vaccine, a mountain of Tamiflu, we are going to need hundreds of thousands more ventillators than we currently have and could hope to produce. Could there be a way to "Macgyver" a ventillator out of common hospital supplies, wall suction, air, O2, PleuraVac and what is known as a PEEP valve. If we could come up with a cheep alternative to the expensive ventillator machines, potentially hundreds of thousands of lives could be saved from H5N1 avian flu pandemic.