The Eye of the Finch.

The article reflects on the potential of novel strains of bacteria and viruses to jump from one host species to another in order to cause a disease outbreak such as spread of an H7N9 strain of influenza virus in China. It informs about the a study published in the periodical PLOS Biology in 2013 which states that Mycoplasma gallisepticum which affects the eyes of finches and found in the U.S. has rapidly and repeatedly evolved to become both more and less harmful to its songbird hosts.