Plague and Animals
Plague and Animals: Where Is Plague Common?In the United States, the last urban plague epidemic occurred in Los Angeles in 1924-1925. Since then, human plague in the United States has occurred as scattered cases in rural areas (an average of 10 to 15 people are infected each year).
Most human cases of plague in the United States occur in two regions:
- Northern New Mexico, northern Arizona, and southern Colorado
- California, southern Oregon, and far western Nevada.
Rock squirrels and their fleas are the most frequent sources of human infection in the Southwestern states. As for the Pacific states, the California ground squirrel and its fleas are the most common source.
Globally, the World Health Organization (WHO) reports 1,000 to 3,000 cases of plague every year. Plague is more common in Africa, Asia, and South America (see Where is Plague? for more information).
(Click Bubonic Plague Pictures to see a worldwide map of where plague is common in animals and humans.)
How Does Plague Survive If It Kills All Animals?During an outbreak, plague bacteria are able to survive for several months in cool, moist conditions, such as the soil of a rodent hole.
Between outbreaks, the plague bacteria are believed to circulate within populations of certain species of rodents without causing excessive death. Such groups of infected animals serve as silent, long-term reservoirs of infection.
During a plague outbreak, there are precautions a person can take to reduce the chances of plague transmission from animals. Some of these precautions include:
- Do not pick up or touch dead animals.
- If plague has recently been found in your area, report any observations of sick or dead animals to the local health department or law enforcement officials.
- 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.
- 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 live in an area where rodent plague occurs, treat pet dogs and cats for flea control regularly, and do not allow pets to roam freely.
- Health authorities may use appropriate chemicals to kill fleas at selected sites during animal plague outbreaks.