Trailing Normal: The Bubonic Plague

When I say the word plague, does it conjure up images like this?

Spread of the Black Death in Europe (1346–53)

Or, perhaps a certain Monty Python sketch?

I thought we had buried the Black Death back in the 14th century. I mean, wasn't this disease supposed to be under control, if not eradicated?

The bubonic plague

Remember how back in July, parts of Yumen, a city in North West China were placed under quarantine after a man died of the bubonic plague? The victim had apparently contracted the disease from a dead rodent. Yes, apparently the plague is still around. In fact, while parts of Yumen were under quarantine, there were three new confirmed cases in Colorado, USA.[1]

According to a National Geographic[2] article entitled, Plague The Black Death,

Plague still exists in various parts of the world. In 2003, more than 2,100 human cases and 180 deaths were recorded. The United States, China, India, Vietnam, and Mongolia are among the other countries that have confirmed human plague cases in recent years.

The Bubonic plague or 'black death' is a potentially fatal infection caused by the bacterium Yersinia pestis.[3] (The one all 'lighted up' in green on the left of the screen.)

If left untreated, bubonic plague kills about 50 percent of those it infects.[2]

Oriental rat flea infected with Y. pestis
which appears as dark mass in the gut.

"The bacteria began its life harmlessly living in the digestive tracts of mammals. The ability to propagate was dependent only upon its ability to travel from mammal host to mammal host. The bacteria remained harmless to the flea, allowing the new host to spread the bacteria. The bacteria form aggregates in the gut of infected fleas and this results in the flea regurgitating ingested blood, which is now infected, into the bite site of a rodent or human host. Once established, bacteria rapidly spread to the lymph nodes and multiply."[4]

Transmission

According to the CDC,[5] the plague bacteria can be transmitted to humans in the following ways:

Flea bites. Plague bacteria are most often transmitted by the bite of an infected flea.

Contact with contaminated fluid or tissue. Humans can become infected when handling tissue or body fluids of a plague-infected animal.

Infectious droplets. When a person has plague pneumonia, they may cough droplets containing the plague bacteria into air. If these bacteria-containing droplets are breathed in by another person they can cause pneumonic plague. Typically this requires direct and close contact with the person with pneumonic plague. Transmission of these droplets is the only way that plague can spread between people.

Our pets can contract the plague from infected rodents by either biting or being bitten by the rodent.[6]

Cats are particularly susceptible to plague, and can be infected by eating infected rodents. Sick cats pose a risk of transmitting infectious plague droplets to their owners or to veterinarians.[5]
(Those living in the southwest US, might want to think twice about letting their pets roam around freely between May and October, just sayin'.)

Plague can be treated with antibiotics such as streptomycin and tetracycline.[7]

It is estimated the plague reduced the world population from an estimated 450 million down to 350–375 million in the 14th century.[8]

"Some of the earliest instances of biological warfare were said to have been products of the plague, as armies of the 14th century were recorded catapulting diseased corpses over the walls of towns and villages to spread the pestilence."[4]

Signs and symptoms

According to the CDC,[9] the most common forms of plague are bubonic, pneumonic and septicemic.
Symptoms include:

Bubonic plague: Patients develop sudden onset of fever, headache, chills, and weakness and one or more swollen, tender and painful lymph nodes (called buboes). This form usually results from the bite of an infected flea. The bacteria multiply in the lymph node closest to where the bacteria entered the human body. If the patient is not treated with the appropriate antibiotics, the bacteria can spread to other parts of the body.

Septicemic plague: Patients develop fever, chills, extreme weakness, abdominal pain, shock, and possibly bleeding into the skin and other organs. Skin and other tissues may turn black and die, especially on fingers, toes, and the nose. Septicemic plague can occur as the first symptom of plague, or may develop from untreated bubonic plague. This form results from bites of infected fleas or from handling an infected animal.

Pneumonic plague: Patients develop fever, headache, weakness, and a rapidly developing pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery mucous. Pneumonic plague may develop from inhaling infectious droplets or may develop from untreated bubonic or septicemic plague after the bacteria spread to the lungs. The pneumonia may cause respiratory failure and shock. Pneumonic plague is the most serious form of the disease and is the only form of plague that can be spread from person to person (by infectious droplets).