In the book Man and Microbe the author in describing the history of
the plague states that cold weather caused the Y. pestis attack to
shift from the lymph nodes (the bubonic form) to the lungs (the
pneumonic form herby enabling it to be transmitted via aerosols. In
my Medical Microbiology class I learned that the pneumonic form is
considered to be the secondary stage of the infection but the
professor was unable to answer whether or not this occurs in all cases
or just through some external stimuli. He seemed to imply that it
happened every time.
Does anyone know the answer?
