As much as we would like to think otherwise, the infamous Black Death of the 14th century has never fully vanished. In fact, around 200 cases of the plague are reported every year, with most incidents confined to Madagascar, Peru, and the Congo. The key word here is “most.” In 2015 alone, we have already seen two plague deaths in Colorado and a child’s infection (and subsequent recovery) in California.
While it’s incredibly rare, the plague still exists in North America—and one of the best ways to survive the plague is to be well-informed.
The plague is caused by Yersinia pestis (Y. pestis) bacteria that infects small rodents and fleas. It can be spread by contact with infected fluids or physical contact with an infected person or surface, and it can even remain airborne for extended periods of time. Despite the numerous means of transmission, the bacterium enters humans mainly by being passed along by fleas.
When a flea becomes infected with Y. pestis, whether through the environment or from feeding on an infected rodent, the bacteria multiply and create a “plug” that blocks the flea’s stomach. When the flea bites something else, such as a human, it attempts to draw blood—but the plug causes it to vomit instead. This delivers Y. pestis directly into the wound.
There are three variations of the plague. Unlike other diseases, the different forms of the plague are not caused by different bacteria of the same family. Instead, the type of plague infection someone gets—bubonic, septicemic, or pneumatic—depends on where the Y. pestis infection is localized. Generally speaking, symptoms of all three forms will appear within two to five days of infection.
The bubonic plague is the most common form of the plague—and the one most people associate with the disease. The bubonic plague ravaged medieval Europe and even today, it is capable of killing two-thirds of patients without treatment. Bubonic plague happens when Y. pestis enters the lymph nodes, which is most likely the outcome following a flea-bite transmission. Once inside the lymph node, the bacteria begin to replicate. This multiplication, along with the toxins the bacteria produces, creates numerous symptoms that can appear suddenly.
The trademark sign of bubonic plague are the swollen, black lymph nodes called bubo. They are the result of bacteria multiplying inside the lymph nodes. Bubo tends to appear near the site of the flea bite, along with the armpit, groin, or neck. In advanced states, these swellings can sometimes turn into open sores.
The second most dramatic symptom is gangrene around the fingers, lips, nose, and toes. Additional symptoms of bubonic plague are high fever, muscle cramps, chills, bloody vomit, delirium, sometimes seizures, and a general feeling of illness called “malaise.”
As unpleasant as the bubonic plague is, this is still the preferred form of a plague infection. Y. pestis can do a great deal of damage while confined to the lymph nodes, but bubonic plague is the slowest progressing form of the disease. This slow progression, combined with the signature bubo, means that it has the highest chance of being detected and treated.
Septicemic plague occurs when Y. pestis enters the bloodstream. This usually happens as a result of environmental transmission (i.e. through the skin or from exposure to tainted fluids), although flea bites can cause it on occasion. A Colorado teenager who died in July 2015 contracted septicemic plague from a flea bite. In some cases, bacteria from a bubonic infection can drain into the bloodstream and cause a secondary septicemic plague.
Once inside the bloodstream, Y. pestis and its toxins trigger an effect called disseminated intravascular coagulation (DIC). This is a scientific way of saying your clotting factors freak out. The clotting cascade—a series of chemical reactions that happen when you are injured—goes into overdrive and small clots form throughout your entire body. As parts of the body are deprived of oxygen, localized necrosis and gangrene can occur. It may be hard to believe, but this is not the most problematic symptom.
You are likely familiar with the phrase “blood is thicker than water.” Part of the reason this is true is because of the clotting factors inside your blood. Deprived of those factors, such as from a massive case of DIC, your blood becomes very “thin.” This causes a prolific amount of internal bleeding as blood leaks into the skin and organs.
Septicemic plague is very fast-acting. Patients can die before symptoms even appear, and if untreated, almost all will die within a day of showing symptoms. Those who do show symptoms will typically exhibit a patchy red “rash” where blood has begun to pool under the skin. They will also develop bleeding from the mouth, nose, or rectum and display symptoms of a fever and chills.
The bleeding causes a number of secondary symptoms, most notably low blood pressure, shock, and organ failure.
Pneumatic plague is the rarest form of the disease, which is fortunate since it is also the most contagious. Septicemic and bubonic plague are most commonly caught from animals or fleas, but pneumatic plague is capable of being spread from person-to-person. Pneumatic plague is when the Y. pestis infection enters the respiratory system. There are two ways to contract it: when a septicemic or bubonic infection enters the lungs or when someone inhales infected droplets.
The initial symptoms of pneumatic plague are similar to pneumonia and include fever, weakness, headache, nausea, chest pain, cough, bloody saliva, and shortness of breath. This is the only form of plague that causes a cough, which is probably a good thing. When a pneumatic patient coughs, they release droplets filled with Y. pestis that can be inhaled to further spread the disease.
Although far less dramatic in appearance than bubonic or septicemic plague, pneumatic plague is very good at what it does. Without treatment, it has an effective 100% mortality rate.
Treatment of the Plague
Treatment for any form of the plague is straightforward—antibiotics, and lots of them. For all of its dangers, many common antibiotics can treat and cure the plague if administered early enough. If the disease has managed to progress, more aggressive forms of antibiotics may be used as well. For cases of bubonic or septicemic plague where gangrene occurs, surgery may be needed to remove the decaying tissue.
When a case of plague has been identified, those who have been in proximity to the patient are normally placed on a pre-emptive antibiotic series as well.
Avoiding the Plague
As mentioned previously, very few cases of the plague occur annually. Most people, therefore, do not need to take any extra precautions to avoid infection. However, if you live in an area that has recently seen a case of the plague, there are a few useful steps you can take:
- Use insect repellant when camping, hiking, or working outdoors to deter fleas.
- Apply flea control products to your pets, and do not allow pets to roam outdoors.
- Do not handle live rodents or skin dead ones without gloves.
- Rodent-proof your home and clear out any viable habitats on your property, such as piles of junk or wood.
- Avoid wild animals that show signs of illness.
Botelho, G., “Adult Dies of Plague in Colorado,” CNN web site, August 6, 2015; http://www.cnn.com/2015/08/05/health/colorado-plague-death/.
Dean, J., “Colorado plague deaths: Second person killed by deadly disease caught from rat,” The Mirror web site, August 6, 2015; http://www.mirror.co.uk/news/world-news/colorado-plague-deaths-second-person-6204839.
“Plague,” World Health Organization web site; http://www.who.int/mediacentre/factsheets/fs267/en/, last accessed August 10, 2015.
“Plague,” Centers for Disease Control and Prevention web site, June 19, 2015; http://www.cdc.gov/plague/.