The biology of the H5N1 avian influenza virus is rife with paradoxes. The virus is widespread, but hard to detect. It kills more than half of the people known to be infected, but thousands of those exposed have no apparent problems. It seems to be just a few mutations away from gaining the ability to spread from person to person, but despite more than 16 years of fast-paced evolution, it has failed to do so.
展开▼
