Human Contraction of the Plague From Prairie Dogs

The illness commonly known as the bubonic plague, describes human infection with Yersinia pestis (Y. pestis) bacteria. Rodents, including prairie dogs, can carry the Y. pestis bacteria. Usually the bacteria only spreads from rodent to rodent but it can spread to humans through flea bites. Although the plague is still considered a life-threatening disease, antibiotics can cure it if it's caught early.

Plague History

• The earliest cases of plague occurred in Asia. Travelers from Asian countries then carried the disease along trade routes. There have been many separate plague epidemics but the biggest was the Black Death, an outbreak in the 14th century that killed 25 million people, or one-third of Europe's population. Another significant outbreak happened in 1665, when the disease killed 15 percent of the English population, spreading rapidly after starting in St. Giles-in-the-Field Parish, which was poor, overcrowded and infested with rats.

  In the middle of the 19th century, another epidemic spread from China to nearly every continent, including North America. By the mid-1900s there were documented cases of infection in black-tailed prairie dogs; the animals had no natural resistance to the bacteria and therefore probably picked it up once it was introduced to the continent.

Modern Cases

• Since the Great Plague, outbreaks of bubonic plague in humans are few and far between. The Centers For Disease Control reports that physicians in the United States diagnose 10 to 20 cases of plague annually. As of 2010 the last two fatal cases of bubonic plague in the United States occurred in 1996. Both cases resulted from contact with infected prairie dogs.

Prairie Dog Infection

• Prairie dogs infected with Y. pestis remain asymptomatic until they are near death. The final symptom, severe swelling, is often the only visible sign of infection. You should report any sightings of sick prairie dogs to animal control officials. Never touch a prairie dog in such condition.

  Because the infection is so hard to detect, and because it is most often transmitted through flea bites, you should keep your distance from wild prairie dogs even if they appear to be healthy. Since the fleas that feed on prairie dogs prefer to bite other animals, keeping household pets free of fleas, and your home free of other rodents like rats, is also important if you live near major prairie dog colonies.

Human Infection

• Drastically swollen lymph nodes, called buboes, indicate bubonic plague infection. The painful buboes range from grape- to baseball-sized lumps. Plague infection causes flu-like symptoms such as fever, headache and general malaise.

  When the Y. pestis bacteria infect the bloodstream, a condition called septicemic plague, the patient may experience shock, sudden onset of chills and gastrointestinal disturbances. In its latter stages, septicemic plague causes gangrene. Gangrene causes tissue death, making the skin appear black, a condition that earned the plague its nickname of "The Black Death."

  Pneumonic plague causes the same symptoms as pneumonia: weakness, fever and difficulty breathing. People at risk for bubonic plague must tell their doctor if they experience symptoms of pneumonia.

Treatment

• Human plague infection is responsive to antibiotics in its earliest stages. The doctor will order a ten-day course of either streptomycin or gentamicin given intravenously. However, with delayed or no treatment, plague in any form is almost always fatal in humans. As of 2010, prairie dogs and other rodents infected with the plague are unresponsive to medical treatment.