Avian influenza, or bird flu, causes an infectious and contagious respiratory disease. In the lab, several scientists have made the H5N1 strain more contagious, a controversial line of research. James Cavallini/ScienceSource hide caption
Avian influenza, or bird flu, causes an infectious and contagious respiratory disease. In the lab, several scientists have made the H5N1 strain more contagious, a controversial line of research. James Cavallini/ScienceSource hide caption