Avian influenza: the next pandemic?

In 1997, a novel strain of influenza A (H5N1) was discovered in poultry in South Asia and China. Since that time, this avian influenza virus has undergone a number of mutational changes and has spread widely in poultry and birds. Its adaptation to migratory birds in 2005 provided the opportunity for even more widespread dissemination, which now includes 50 countries in Asia, Europe, and Africa. Although the virus has yet to obtain the necessary genes for efficient human-human transmission, it has already caused more than 100 human fatalities throughout the world. As the virus continues to propagate widely in birds and poultry, the likelihood of its acquiring the genetic mechanisms for human-human transmission increases. If this does occur, the ensuing worldwide pandemic could be catastrophic.