Virulence is the ability of a microorganism to produce disease. Virulence depends on the number of infecting bacteria, their route of entry into the body, the response of
M. haemolytica is responsible for causing contagious bovine pleuropneumonia, a bacterial disease which causes pneumonia and inflammation of the lung membranes and Bordetella bronchiseptica is an evolutionary progenitor
Only a tiny amount of bacteria found on Earth are actually associated with disease. The number associated with human disease is as low as 0.001%. Bacteria are extremely