Bubba is just up to his usual tricks of spreading half-truths & misinformation about health issues.
If one bothers to read up on the black death or the plague, one quickly finds out that the European Yersinia pestis epidemic probably originated from rat fleas that spread to humans. However, it is not only carried by fleas, but the infection also has pulmonary and blood infection versions. The rapid spread in Europe was not only the flea version, but also the pulmonary version where individuals could get infected from droplets emitted from infected people coughing and spitting.
Luigi