Two new “black death” patients.
For the second time this summer, health officials in California are investigating a case of plague that a camper most likely contracted while visiting Yosemite National Park.
The Centers for Disease Control and Prevention is testing a visitor from Georgia who camped at Yosemite, the Sierra National Forest and the surrounding areas in early August. Two campgrounds were closed after another case was announced two weeks ago. Since then the authorities have been warning visitors of possible plague risks.
Plague, also known as “bubonic plague,” “black plague,” “black death,” and several other appellations, wiped out at least a third of the population of Europe in the 14th century — some historians estimate as high as two thirds — and also very large numbers of people several other times and places. Before entering Europe this time, it had ravaged China, India, and areas along the trade routes of the East.
The same germ had also been responsible for the Plague of Justinian that killed an estimated 25 million people in Europe in 541–542 A.D. and maybe that many more over the next two centuries. It came to Europe and spread there in the blood of the ironically named black rat (pictured above).
The Black Death arrived in Europe by sea in October 1347 when 12 Genoese trading ships docked at the Sicilian port of Messina after a long journey through the Black Sea. The people who gathered on the docks to greet the ships were met with a horrifying surprise: Most of the sailors aboard the ships were dead, and those who were still alive were gravely ill. They were overcome with fever, unable to keep food down and delirious from pain. Strangest of all, they were covered in mysterious black boils that oozed blood and pus and gave their illness its name: the “Black Death.” The Sicilian authorities hastily ordered the fleet of “death ships” out of the harbor, but it was too late: Over the next five years, the mysterious Black Death would kill more than 20 million people in Europe–almost one-third of the continent’s population.
It’s rare among humans now, but it survives in rodent populations in the southwestern United States and elsewhere. The rodents are generally immune to it, but their fleas are not. Fleas ingest the bacteria and become infected when they drink the blood of an infected animal. The bacteria actually multiply in the flea’s gut until they clog up its digestive system and make it vomit when it bites another animal and tries to feed again. It regurgitates infected saliva and blood into the new animal, passing the infection to it. Occasionally, humans gets infected this way.
Yersinia pestis bacterium causes black death.
The disease is caused by the Yersinia pestis bacterium, which can also cause “pneumonic plague” or “septicemic plague.” The difference between the three forms depends only where the infection exists in the body, but that difference is important.
Pneumonic plague, a severe type of lung infection, is one of three main forms of plague, all of which are caused by the bacterium Yersinia pestis. It is more virulent and rarer than bubonic plague. The difference between the versions of plague is simply the location of the infection in the body; the bubonic plague is an infection of the lymphatic system, the pneumonic plague is an infection of the respiratory system, and the septicemic plague is an infection in the blood stream.
Three forms of the disease
An untreated Yersinia pestis infection in the lymph nodes, the bubonic form, may be fatal in humans around 30% of the time. An untreated infection in the lungs, the pneumonic form, is not only more likely to be fatal, but is also more contagious; it is spread through the air when the patient coughs, like the flu is. The untreated septicemic form, in the blood, is fatal in 99% to 100% of patients. However, this form is rare.
The bubonic form is usually caught from the bite of an infected flea. Only rarely does this become one of the other forms. However, in those rare cases when the infection does settle in the lungs (possibly because of a prior lung infection), then it becomes pneumonic and spreads through the air to the lungs of other people. In this form, it can wipe out a whole family in a week.
“In men and women alike,” the Italian poet Giovanni Boccaccio wrote, “at the beginning of the malady, certain swellings, either on the groin or under the armpits…waxed to the bigness of a common apple, others to the size of an egg, some more and some less, and these the vulgar named plague-boils.” Blood and pus seeped out of these strange swellings, which were followed by a host of other unpleasant symptoms–fever, chills, vomiting, diarrhea, terrible aches and pains–and then, in short order, death.
Patients with all forms of this disease usually recover if treated soon enough with antibiotics. Probably the worst danger from black death now is that it’s so rare it’s not always identified in time for treatment to work.
There are a series of short videos on the subject here, where you can learn more than you ever wanted to know about the black death in about 26 minutes total. But be warned, they are gruesome.