ExitCare ImagePlague is caused by the bite of fleas that become infected with bacteria (germ) Yersinia pestis. These fleas become infected by feeding on rodents, such as the chipmunks, prairie dogs, ground squirrels, mice, and other mammals that are infected with the bacteria. Fleas transmit the plague bacteria to humans and other mammals when feeding on them. The plague bacteria are maintained in the blood systems of rodents. The germs causing the plague can be spread from person to person. When another person has plague pneumonia and coughs droplets containing the plague bacteria into air that is breathed by a non-infected person, they can develop the pneumonic (lung) form of the plague. The pneumonic form of the disease would be seen as the primary form after purposeful aerosol dissemination of the organisms. When fleas, which live on the rodents, pass the bacteria to human beings, they then suffer from the bubonic form of plague. The bubonic form would be seen after purposeful dissemination through the release of infected fleas. All human populations are susceptible. Recovery from the disease may be followed by temporary immunity.

People usually get plague from being bitten by a rodent flea that is carrying the plague bacterium or by handling an infected animal. The Xenopsylla cheopis (oriental rat flea) is shown in the picture engorged with blood. This flea is the primary vector of plague in most large plague epidemics in Asia, Africa, and South America. Both male and female fleas can transmit the infection. Today, modern antibiotics are effective against plague, but if an infected person is not treated promptly, the disease is likely to cause illness or death.

Risk: Wild rodents in certain areas around the world are infected with plague. Outbreaks in people still occur in rural communities or in cities. They are usually associated with infected rats and rat fleas that live in the home.


The typical sign of the most common form of human plague is a swollen and very tender lymph gland, accompanied by pain. The swollen gland is called a "bubo." Bubonic plague should be suspected when a person develops a swollen gland, fever, chills, headache, and extreme exhaustion, and has a history of possible exposure to infected rodents, rabbits, or fleas. A person usually becomes ill with bubonic plague 2 to 6 days after being infected.

When bubonic plague is left untreated, plague bacteria invade the bloodstream. As the plague bacteria multiply in the bloodstream, they spread rapidly throughout the body and cause a severe and often fatal condition.

ExitCare ImageInfection of the lungs with the plague bacterium causes the pneumonic form of plague, a severe respiratory illness. The infected person may experience high fever, chills, cough, and breathing difficulty and may expel bloody sputum. If plague patients are not given specific antibiotic therapy, the disease can progress rapidly to death.


  • Controlling rodents and their fleas around places where people live, work, and play is very important.

  • Air out infested spaces before cleanup.

  • Spray areas of infestation and all excreta, nesting, and other materials with household disinfectant or 10% bleach solution then clean up, seal in bags, and dispose.

  • Avoid sweeping, vacuuming, or stirring dust until the area is thoroughly wet with disinfectant.

  • Wear rubber gloves; disinfect gloves before removal, and wash hands afterwards.

  • Effective environmental sanitation reduces the risk of persons being bitten by infectious fleas of rodents and other animals in places where people live, work, and recreate. It is important to remove food sources used by rodents and make homes, buildings, warehouses, or feed sheds rodent-proof. Applying chemicals that kill fleas and rodents is effective but should usually be done by trained professionals. Trained professionals who can inspect and, if necessary, fumigate cargoes should also control rats that inhabit ships and docks.

  • Watch for plague activity in rodent populations where plague is known to occur. Report any observations of sick or dead animals to the local health department or law enforcement officials.

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  • Eliminate sources of food and nesting places for rodents around homes, work places, and recreation areas; remove brush, rock piles, junk, cluttered firewood, and potential-food supplies, such as pet and wild animal food. Make your home rodent-proof.

  • If you anticipate being exposed to rodent fleas, apply insect repellents to clothing and skin, according to label instructions, to prevent flea bites. Wear gloves when handling potentially infected animals.

  • If you live in areas where rodent plague occurs, treat pet dogs and cats for flea control regularly and not allow these animals to roam freely.

  • Health authorities may use appropriate chemicals to kill fleas at selected sites during animal plague outbreaks.


  • The organism will probably remain viable in water and moist meals and grains for several weeks.

  • At near freezing temperatures, it will remain alive from months to years but is killed by 15 minutes exposure to 72° C.

  • It also remains viable for some time in dry sputum, flea feces, and buried bodies but is killed within several hours of exposure to sunlight.

  • Vaccine is no longer available.


  • Health authorities advise that antibiotics be given for a brief period to people who have been exposed to the bites of potentially infected rodent fleas (for example, during a plague outbreak) or who have handled an animal known to be infected with the plague bacterium. Such experts also recommend that antibiotics be given if a person has had close exposure to a person or an animal (for example, a house cat) with suspected plague pneumonia.

  • Persons who must be present in an area where a plague outbreak is occurring can protect themselves for 2 to 3 weeks by taking antibiotics. The preferred antibiotics for prophylaxis against plague are the tetracyclines or the sulfonamides.

Most of this information is courtesy of US Government CDC. In times of an emergency much of this material may not apply when it comes to specialized care and testing. These are guidelines to help you when that care is not available. Some of this information is very technical and difficult to understand, but hopefully someone will be available for help in treatment and understanding.