Bubonic Plague Spread
Bubonic plague is typically transmitted by direct contact with infected tissue or bodily fluids, bites from infected rodent fleas, or inhaling infected droplets. The disease is most commonly spread through the bites of infected fleas. The spread of bubonic plague can also occur when someone handles infected materials or an infected animal and the bacteria enter through the skin.
The bacteria that cause plague (Yersinia pestis) are found throughout certain parts of the world, most commonly in rats, but occasionally in other wild animals, such as prairie dogs. Transmission of bubonic plague from these infected animals generally occurs in one of three ways:
- Inhaling infected droplets
- Direct contact with infected tissue or bodily fluids
- Bites from infected fleas.
Bubonic plague is spread to humans or animals 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 other sources of blood to survive. It is risky for people and animals to visit places where rodents have recently died from plague, because they are more likely to be bitten by infected fleas.
This method of transmission accounts for about 85 percent of the human cases of plague.
The spread of bubonic plague can also occur through direct contact with infected tissue or bodily fluids. For example, people can become directly infected with plague if the plague bacteria enter through the person's skin when handling infected animals.
House cats also are susceptible to plague. Infected cats become sick and may directly spread plague to people who handle or care for them. Plague-infected fleas can also be brought into the home from dogs or cats.