The research, done by the federal Centers for Disease Control and Prevention, gives new insight on the threat of bird flu, which has spread among poultry in Britain and killed a woman in Africa. The flu has already rooted in Asia and spread among birds there on a seasonal basis.
For the flu to spread, the key is in its amino acids – part of the viruses' protein structure. The proteins are used as a pathway to replicate in a body. For the H5N1 strain of deadly bird flu – feared as a pandemic killer but not yet contagious among humans – its amino acids prefer to bind with a sugar called 2,3 - sialic acid. The common flu that affects humans and other mammals, however, utilizes the 2,6 - sialic acid.
With just two mutations in bird flu to change how it operates with mammals, the spread among humans could be catastrophic.
Humans produce both acids, but the 2,6 - sialic acid is in our noses and throats, and that is what most flu strains attack. The 2,3 - sialic acids are in the lungs.
If the bird flu strain of H5N1 mutates to get into the nose and throat, it means that humans can spread it easily through sneezing, coughing and other methods of spreading most diseases. Since it attacks mammals, it is possible that animals like dogs and cats could also become potential carriers of bird flu.
The study also sought to investigate the causes of the 1918 pandemic flu, which killed between 50 million to 100 million people worldwide (between 2.5 and 5 percent of the human population) during the course of 18 months. The CDC found that the virus that was spread in 1918 has a different main protein structure.
The worldwide death toll in the past four years of the H5N1 virus currently stands at more than 165 people.