Bubonic plague is a bacterial disease caused by the organism Yersinia pestis. It is transmitted by the bite of an infected flea, carried by rodents and has been responsible throughout history for many epidemics. One of the most famous occurred in 1348, known as the Black Death, which progressed through Asia and Western Europe. This episode killed approximately one third of the population.
Biologically, this organism is a gram negative rod that is susceptible to a variety of antibiotics.
In the United States, hosts that carry the organism include the white-footed deer mouse, voles, prairie dogs and ground squirrels. Humans can get the plague from direct contact with their dogs and cats and being bitten by infected fleas. You can also get this from disposing of infected mice or rodents. States that still have isolated cases of the plague are Arizona, California, Colorado, Nevada, New Mexico, and Utah. On average, there are about seven cases per year. ( CDC graph )
Three types of illness are bubonic, septicemic and pneumonic. The most common being bubonic.
Important side note – Dogs and cats can acquire plague from flea bites, but again, this is more common in the southwestern United States. Dogs rarely become ill, however, cats become very ill and can die. Cats acquire pneumonic plague and can transmit it through their bite. Again, to put this in perspective, plague is rare and plague in cats is rare, so one would have to have a substantial bite from an infected cat before this can be transmitted.
The most common form of plague is bubonic. It is characterized by buboes which are large, tender lymph nodes, which often feel like nodules or marbles under the skin. These lymph nodes form away from where the flea bit you. The incubation period is 2-6 days. It is not uncommon to get dark, blackened lesions on the skin, hence theorem “Black Death.” Other common symptoms are fever, chills, nausea, vomiting and headache.
Plague is more common in individuals less than forty years old due to younger individuals being more likely to explore the outdoors and camp or hike.
A complete history is important when trying to assess for the illness. (Specifically, a travel history.) Does the person hunt out west or camp? Have they done any skinning or butchering of animals? Have they travelled to another country? If one does suspect the plague, antibiotics should be started before any labs are back. If it is not the plague, you can always stop the meds later.