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The Plague


What is the plague?

The plague is an infectious disease caused by a bacterium called Yersinia pestis that can affect both animals and humans.

There have been many outbreaks of plague in human history, which have killed more than 200 million people around the world. Perhaps the most widely known plague is the Black Death of 14th century Europe. This was bubonic plague.

Outbreaks of plague are a rare occurrence today.

How is the plague transmitted?

At the present time, it is extremely rare for humans to contract plague. The plague is transmitted between animals and humans by the bite of infected fleas, direct contact with infected rodents, inhalation and rarely, ingestion of infective materials. Contact with infected fleas typically occurs in wilderness settings or through domestic pets transporting infected fleas or dead rodents into the home.

Is there more than one type of plague?

There is only one cause of plague, but there are three different types of illness that the infection can cause. They are bubonic, pneumonic and septicemic plague.

  • Bubonic plague is the most common. The infection appears in the lymph nodes, causing them to swell and become painful. Infection results from the bite of an infected flea that has fed on an infected rodent, such as a rat.
  • Pneumonic plague is the most deadly form of plague but least common. It can be spread through airborne droplets released through coughs or sneezes, or through contact with infected body fluids. It can also be spread through contact with clothing or bed linens that have been contaminated with infected body fluids.
  • Septicemic plague can occur with either bubonic or pneumonic plague.

What are the symptoms of plague?

The incubation period for the plague is 1 to 10 days.

In all forms of plague, symptoms begin with flu-like complaints like fever, chills, muscle pain, weakness and headache, and can include nausea, vomiting, diarrhea and abdominal pain.

Are there any treatments for the plague?

Rapid diagnosis and treatment is essential to reduce complications and fatality. Effective treatment methods enable almost all plague patients to be cured if diagnosed in time. Several antibiotics can effectively treat plague along with supportive therapy.

Is there a vaccine for the plague?

There is a vaccine to protect people who are at high risk of exposure to the disease, such as military personnel under certain operational circumstances, or animal handlers in plague endemic areas. The vaccine requires multiple doses, frequent booster shots are needed and it can have significant side effects. The vaccine is not available for general public use.

Do plagues still occur today?

Human infections with plague still occur occasionally in North America. For instance, 10 to 15 cases occur every year in the southwestern United States. In 1996, two deaths were attributed to plague in the United States. These cases resulted from contact with infected wild animals. Human cases of plague are very rare in Canada with the last case reported in 1939.

What precautions should you take to avoid the plague?

The plague is usually transmitted from animals to humans from wildlife rodents or their fleas. In areas where the plague is established in wildlife populations, people should avoid contact with the habitats where infected rodents or fleas might reside. If these areas can not be avoided then wearing appropriate clothing (e.g., long pants, closed toed shoes and pants tucked into socks) and insect repellents containing DEET can protect against flea bites. If dead animals must be handled use appropriate personal protection including wearing gloves, double bagging of carcasses, and thorough hand-washing and disinfection of potentially contaminated surfaces.

Outdoor cat owners should be especially vigilant in areas populated with infected rodents. Cats have been known to transmit the disease to humans either through bringing infected rodents home or contracting bubonic plague which they can transmit to humans.

Additional information on plague can be found at the following web sites: