Pests & Plague in Greater Boise Area

Author: Kurt Treftz, Cascade Pest Control

When most people hear the word “plague”, they immediately conjure up images of mass death, suffering, and fear. The recent case of a plague in a man from California raises those fears again. However, this isn’t the first case of plague in the area in recent years, and it probably won’t be the last. While Idaho has had no recent issues of human infestations, plague has been a threat in wildlife throughout Ada County, including Boise, Garden City, Eagle, Meridian, Nampa, Caldwell, and Kuna sporadically in the last few decades.

Recent Case of Plague

• In August 2025, a man from South Lake Tahoe, California, tested positive for plague.
• He likely contracted it from the bite of an infested flea while camping.
• The patient received medical care and is recovering at home.
• This is the first human case in the region since 2020
• Idaho has had no reported human cases in recent years; however, an Idaho boy contracted it in 2018 and recovered after medical treatment.
• The western United States has naturally occurring plague in wildlife populations. In 2015 and 2016, the disease was confirmed in ground squirrels in south Ada County of Idaho. 
• In June 2024, a case of plague was confirmed in a mule deer in Custer County, Idaho.
• Plague has been detected in rodents, including rats, ground squirrels, deer mice, muskrats, and prairie dogs, as well as in some carnivores, such as coyotes, foxes, bobcats, and mountain lions. Most transmission is mainly via infected fleas.

History of the Plague

Also known as “the Black Death”, plague is a disease caused by the bacterium Yersinia pestis. There have been numerous pandemics throughout history, but the most notable was likely the outbreak in the 14th century. Beginning in central Asia and traveling along trade routes, plague swept through Europe, decimating the population. Nearly two-thirds of the population succumbed to the disease, which was spread through rats carrying the oriental rat flea. Bites from the infected fleas spread the bacterium. 

Symptoms of Plague

• Sudden fevers, chills, headache, and weakness beginning 1-8 days after exposure
• Swelling of lymph nodes in the groin, armpits, and / or neck, called buboes
• Buboes can be extremely tender and painful to touch. They can become red and warm.
• If untreated, the infection can become systemic. If the disease enters the bloodstream, further symptoms develop: bleeding into the skin and organs, shock, and potentially skin or tissue death (gangrene).
• However, modern treatment with antibiotics is remarkably effective against plague, and few humans die of plague today. Because symptoms can progress rapidly, it is advised to begin medical treatment early. 

Avoiding the Plague. . . Like the Plague

Plague Precautions

There are steps to take to reduce the chances of getting and spreading plague.

• Plague in the US is rare in humans, but it is present in wildlife. Take precautions in outdoor activities, especially in areas inhabited by rodents.
• Health officials in Idaho continue to surveil and advise the public in cases of plague. Avoid contact with sick, blind, or dead wildlife. 
• Early medical intervention is still key. Treatment with antibiotics is critical. 
• Take proactive measures and keep your home rodent-free with Cascade Pest Control.