Why plagues

The bacteria can also enter your body if a break in your skin comes into contact with an infected animal's blood. Domestic cats and dogs can become infected with plague from flea bites or from eating infected rodents.

Pneumonic plague, which affects the lungs, is spread by inhaling infectious droplets coughed into the air by a sick animal or person. The risk of developing plague is very low. Worldwide, only a few thousand people develop plague each year.

However, your plague risk can be increased depending on the area where you live and travel, your job, and your hobbies. Plague outbreaks are most common in rural and semirural areas that are overcrowded, have poor sanitation and have a high rodent population. The greatest number of human plague infections occur in Africa, especially the African island of Madagascar. Plague has also been transmitted to humans in parts of Asia and South America. In the United States, plague is rare, but it has been known to occur in several western and southwestern states — primarily New Mexico, Arizona, California and Colorado.

Veterinarians and their assistants have a higher risk of coming into contact with domestic cats and dogs that may have become infected with plague. People who work outdoors in areas where plague-infected animals are common are also at higher risk of getting plague. Camping, hunting or hiking in areas where plague-infected animals reside can increase your risk of being bitten by an infected flea.

No effective vaccine is available, but scientists are working to develop one. Top of Page. Fleas become infected by feeding on rodents, such as chipmunks, prairie dogs, ground squirrels, mice, and other mammals that are infected with the bacterium Yersinia pestis.

Fleas transmit the plague bacteria to humans and other mammals during a subsequent feeding. The plague bacteria survive briefly a few days in the blood of rodents and for longer periods in the fleas.

An illustration of plague ecology in the United States is available. Yes, when a person has plague pneumonia they may cough droplets containing the plague bacteria into air. If these bacteria-containing droplets are breathed in by another person they can cause pneumonic plague. Human-to-human transmission is rare and typically requires direct and close contact with the person with pneumonic plague. A person usually becomes ill with bubonic plague 2 to 6 days after being infected.

Someone exposed to Yersinia pestis through the air would become ill within 1 to 3 days. When bubonic plague is left untreated, plague bacteria can invade the bloodstream. When plague bacteria multiply in the bloodstream, they spread rapidly throughout the body and cause a severe and often fatal condition called septicemic plague.

Untreated bubonic plague can also progress into an infection of the lungs, causing pneumonic plague. If plague patients are not given specific antibiotic therapy, all forms of plague can progress rapidly to death. The first step in plague diagnosis is evaluation by a health worker. Once the laboratory receives the sample, preliminary results can be ready in less than two hours. Laboratory confirmation will take longer, usually 24 to 48 hours. This wild African cat has adapted to life in a big city.

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