Bubonic Plague Transmission
Yersinia pestis (the bacteria that causes plague) is often found in animals such as rats and prairie dogs. Bubonic plague transmission usually occurs through bites from infected rodent fleas, direct contact with infected tissue or bodily fluids, or inhaling infected droplets. The disease is spread most commonly through the bites of infected fleas. Bubonic plague transmission from person to person is extremely rare.
Yersinia pestis (the type of bacteria that causes plague) is found in animals throughout certain parts of the world, most commonly in rats, but occasionally in other wild animals, such as prairie dogs. Plague transmission from these infected animals generally occurs in one of three ways:
- Bites from infected rodent fleas
- Direct contact with infected tissue or bodily fluids
- Inhaling infected droplets.
Bubonic plague transmission to humans or animals is usually through the bites of infected rodent fleas (see Plague and Animals for other animals that can transmit plague). During rodent plague outbreaks, many animals die, and their hungry fleas seek out other sources of blood to survive. People and animals that visit places where rodents have recently died from plague risk being bitten by infected fleas.
This method of plague transmission accounts for about 85 percent of the human cases of plague.
House cats also are susceptible to plague. Infected cats become sick and may directly transmit plague to people who handle or care for them. Also, dogs and cats may bring plague-infected fleas into the home.
Inhaling droplets expelled by the coughing of a plague-infected person or animal (especially house cats) can result in plague of the lungs (a condition called pneumonic plague). Pneumonic plague transmission from person to person is uncommon, but sometimes results in dangerous epidemics that can spread quickly. However, this type of plague has not been seen in the United States since 1924.