James Hamilton, M. D.
History from the Medical Viewpoint: Quiz #3
History does, indeed, repeat itself. What we think of as ancient diseases may be on the verge of becoming common again.
Murine Typhus (not to be confused with Typhoid Fever, a totally different infection) is caused by the bacterium Rickettsia typhi. It is one of those zoonotic diseases than can be transferred to humans from animals. In February, 2019 there was an epidemic of Murine Typhus which started in the homeless population of Las Angeles but also spread to others outside of that group. This, like some other infections, often occur in areas of dense population with unsanitary living conditions.
Tuberculosis, another bacterial disease, caused by Mycobacterium tuberculosis, still has a presence in America but, in recent years, has experienced an increase in prevalence. Again, this is being seen in the homeless population as well as drug and AIDS individuals, many of which are also homeless.
Bubonic Plague - the "Black Death" - caused the death of about 25 percent of Europeans in the Middle Ages. The "plague" is endemic (always present in low numbers) among small animals in the West and Southwest. The causative agent is the bacterium Yersinia (formerly Pasturella) pestis. In the small animals which inhabit the forests and plains, it is known as Sylvatic Plague and several species can be affected including prairie dogs and ground squirrels ("chipmunks"). A "die-off" of a colony of prairie dogs is almost a sure sign that the colony was infected with Y. pestis. On my drives down to Fort Carson I pass several colonies of prairie dogs.The ground squirrels in Rocky Mountain National Park are notorious beggars for snacks and come right up to tourists who stop along the trails and sit on boulders to catch their breaths. Another term, Urban Plague, is the same disease but more common in city dwelling animals such as cats. Bubonic Plague in humans can take three forms: Bubonic Plague, Septicemic Plague and Pneumonic Plague. Every now and then a case of the Bubonic form is diagnosed and treated in Colorado or neighboring states before it reaches the Septicemic or Pneumonic stage.
In densely populated areas where Plague or Typhus is present the main reservoir animals are rats (thus the name "Murine" for that form of Typhus). Rats are very prevalent in some of the homeless camps.
With Typhus and TB on the rise could we be looking forward to a resugence of the Black death? It is a frightening, but possible, thought.
1. I have mentioned several reservoirs of Bubonic Plague. What is the vector that can transmit it to humans?
A. Mosquitos
B. Fleas
C. Cockroaches
D. Ticks
E. House Flies
2. What are "buboes"?
A. Spotty, red rashes on the palms and soles
B. Edema (swelling) around the orbits of the eyes
C. Deformities in the bone and cartilage of the nose
D. Enlarged lymph nodes in the axilla and inguinal region
E. Calcified nodules in the upper lungs
3. What form of Bubonic Plague can be transmitted human to human?
A. Bubonic
B. Septicemic
C. Pneumonic
D. All of the above
E. None of the above
Enjoy a nice walk in the woods this weekend but DON'T FEED THE ANIMALS!
Jim
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