Yersinia pestis infection epidemiology and demographics

Epidemiology and Demographics
People usually get plague from being bitten by a rodent flea that is carrying the plague bacterium or by handling an infected animal.



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. In the United States, the last urban plague epidemic occurred in Los Angeles in 1924-25. Since then, human plague in the United States has occurred as mostly scattered cases in rural areas (an average of 10 to 15 persons each year). Globally, the World Health Organization reports 1,000 to 3,000 cases of plague every year. In North America, plague is found in certain animals and their fleas from the Pacific Coast to the Great Plains, and from southwestern Canada to Mexico. Most human cases in the United States occur in two regions: 1) northern New Mexico, northern Arizona, and southern Colorado; and 2) California, southern Oregon, and far western Nevada. Plague also exists in Africa, Asia, and South America (see map).

Can animals transmit plague to people?

Yes, people can get plague from an infected animal, but this is very rare. Rodents (for example, mice, rats, and squirrels) and cats are animals that can carry plague. This disease most often occurs in the southwestern part of the United States. Usually, people get plague from the bite of an infected flea. Since fleas bite both people and animals, especially cats and rodents, an infected flea can pass plague to animals or people. Sometimes, people get plague from working with an animal that is infected. People also can get infected by breathing in tiny droplets of water contaminated with Y. pestis.

Resources
CDC1 CDC2