Plague, scientific name Yersinia pestis, is a bacterial infection that can kill its victims in a few days. You are probably more familiar with the word used in the phrase “The Black Plague” that struck Europe in the 13th-15th centuries. While you may think the plague is a just a disease of the Middle Ages, plague continues to threaten animal and human health here in the United States.
Plague first appeared in the United States in San Francisco in 1900. From there it spread to rats and California ground squirrels.

While fleas were suspected in transmitting plague as early as 1898, it wasn’t proven until William Glen Liston demonstrated that fleas spread plague in 1905. Fleas spread plague by biting an infected victim, obtain the bacteria, then transmit that bacteria onto uninfected victims upon biting them. Although plague can be spread by coughing (called pneumonic plague), this transmission method is not as common.
Today, plague has spread across the west as far as the Missouri River. Fortunately, plague only affects a few people each year in the United States. While that is good news, its rarity also means that those who get infected may not think they have plague and delay receiving life-saving treatment.
So, if you live in plague country (the western half of the United States, here are a few facts to reduce your risk of contracting this lethal disease.
- Avoid areas with populations of rats, ground squirrels and prairie dogs.
- Understand that even if you don’t enter those areas, your cat or dog may bring the fleas to you. In fact, cats are a significant source of plague infections in the U.S. (this is one reason to keep your cat indoors).
- Be aware that you live in plague country. If you develop symptoms such as fever, headache, chills, muscle pain, and fatigue, consider the possibility that you have plague. Other symptoms include nausea, vomiting and diarrhea. Lymph nodes near the exposure site become enlarged, typically the groin, armpits, or neck.
- Symptoms appear two to six days following the exposure.
- Plague can be contracted by handling wild animals such as when hunting, trapping, or during the fur handling process. It is a good practice to kill fleas before handling carcasses. Wear protective gloves as infection can occur through exposure to contaminated animal tissues.
House cat is a common source of fleas that cause plague (Yersinia pestis) . - Advise your doctor of your activities as he/she may not automatically think of plague when you relate your symptoms. Learn about getting prepared for zoonotics if you work with wildlife.
Follow the above steps/principles and the likelihood of your contracting plague will be extremely low.
If you wish to have additional information visit https://www.cdc.gov/plague/index.html or read Abbott, R.C. and Rocke, T.E. 2012. Plague. U.S. Geological Survey Circular 1372. 79p.
Stephen M. Vantassel, CWCP, ACE, is the owner of Wildlife Control Consultant, LLC. He helps people restore their balance with nature through publishing, training, consulting, and the internet. He has published numerous articles in trade and academic publications available at {Stephen’s Academia.edu Page} along with several books {WCC Store}). Listen to his podcast “Living the Wild Life” at {Pest Geek Podcast}. Please subscribe to {Stephen’s YouTube Channel} He is a sought after speaker and trainer. If you would like to have Stephen speak at your event or use his consultation services, send an e-mail to [email protected] Copyright All postings are the property of Stephen M. Vantassel and Wildlife Control Consultant, LLC. Text (not images) may be reprinted in non-profit publications provided that the author and website URL is included. If images wish to be used, explicit and written permission must be obtained from Wildlife Control Consultant, LLC.