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United States of America


United States of America For Specific Travellers:


Known areas of risk are present in remote areas of Arizona (northeastern part), California (all areas bordering Nevada from Lake Tahoe to the Mexican border), Colorado (the central part of the state with scattered areas in the south bordering New Mexico), Idaho (areas bordering the southern part of western Montana and areas bordering Wyoming), Montana (southwest part), Nevada (northeastern part), New Mexico (the entire state), Oregon (central areas and southeastern parts bordering California and Nevada), Texas (areas extending from the city of Lubbock to the border with New Mexico), Utah (scattered areas in the central and southern parts of the state), Washington (central and eastern parts of the state), Wyoming (the southern half and in the north around the Big Horn Mountains).



Plague is a zoonosis – an animal disease that can spread to humans – caused by Yersinia pestis bacteria. It is transmitted to humans through the bite of infected fleas that live among rodents such as squirrels, chipmunks, woodrats, prairie dogs, rabbits, and mice. There are three forms of the infection:

  1. Bubonic plague primarily affects the lymph nodes.
  2. Septicemic plague affects the bloodstream and can be contracted by handling infected animals.
  3. Pneumonic plague affects the lungs and can spread from person to person, though rarely, through contaminated air droplets.

Plague is primarily found in arid regions of Africa, South America, Asia, and North America. Hikers, campers, hunters, and persons occupationally exposed to wild rodents in endemic areas such as anthropologists, archeologists, geologists, spelunkers are at greater risk of exposure.


Flu-like symptoms appear 1 to 10 days after being bitten, including fever, headache, chills, muscle pain, weakness. The illness is also characterized by painful lymph glands. If untreated, the infection can spread to the bloodstream, also known as septicemic plague, which is accompanied by abdominal pain, shock, internal bleeding of organs and skin tissue that may turn black. Pneumonic plague can also develop if bubonic or septicemic plague is untreated. In this case, symptoms include shortness of breath, chest pain, and coughing blood or watery mucous. Shock and respiratory failure can become fatal. Rapid diagnosis and treatment with antibiotics is important for a full recovery. Patients need to be isolated to prevent spreading the infection to others.

  • Ensure that your accommodation or camping area is free of rodents.
  • Remove any food sources or potential nesting materials. 
  • Avoid direct contact with rodents, carnivores who eat rodents, and dead animal tissues. 
  • Make sure cats and dogs around you do not carry fleas. 

There is currently no commercially available vaccine or preventive medication against Plague.

Yersinia pestis bacteria images, life cycle, and distribution maps:

Infection Landscapes

Information last updated: October 23, 2020

Travel Health Journal