Plague Risk Rises in the US Due to Rodent Surge
Travelers across the United States are receiving warnings about an unexpected rise in plague risk, attributed to a significant increase in rodent populations nationwide.
This year, researchers at the University of Richmond pointed to urbanization and rising temperatures as contributing factors to infestations. Among global cities, the US experienced some of the most considerable population spikes, with Washington, D.C. witnessing the highest rates of rat increases, followed by San Francisco, Toronto, and New York City.
Rodents can carry the plague bacteria known as Yersinia pestis and transfer this deadly illness to humans through flea bites or direct contact with infected animals. In fact, Lake Tahoe, California—hosting over 15 million visitors annually—has reported two cases this year amid an uptick in vermin.
Eric Brooks, who recently vacationed with his family at Lake Tahoe, received a pre-arrival email about a “surge in mouse activity” in the area, mentioning hardware stores running out of traps.
This notice from Agate Bay Realty Lake Tahoe indicated that out of their five properties, some were encountering rodent infestations, though remediation efforts were underway.
Brett Williams, the broker and owner, pointed out that pest control experts, some with four decades of experience, have labeled this the “year of the mouse” due to the overwhelming numbers.
From 2021 to 2024, 41 rodents tested positive for the plague in the Tahoe Basin of El Dorado County, with an additional four cases confirmed this year, totaling 45. Following an outbreak, a camper in the area contracted the plague but made a full recovery after medical treatment.
Brooks noted his visits to local hardware stores, where staff reported a noticeable spike in sales of rodent traps and poison, leading to a shortage of supplies. One employee remarked, “We get cleared out by the end of the day. Everyone in town is going through the same thing right now.”
At North Shore Ace Hardware in Kings Beach, assistant manager Maurice Jacques mentioned that locals haven’t seen such a scenario in 15 to 20 years. He added, “We’ve been upping our orders on mouse traps; anything rodent-related is flying off the shelves.”
Sergio Arias from Tahoe Pest Management noted that the rodent issue started emerging in March, escalating quickly by summer. “This year has been unbelievably busy for these rodents,” he said, adding that he now gets up to 60 calls per week compared to just 20 calls a month previously. In fact, during one recent case, he removed 70 rats from a single property.
Arias recalled a more severe incident in a vacant home, where about 150 rats were found. “They’re chewing through the siding and wood on people’s homes to get into walls,” he explained.
In August, a Lake Tahoe resident tested positive for the plague after a flea bite while camping. California health officials stated that the individual was recovering at home under medical supervision. This marked El Dorado County’s first confirmed plague case since 2020. It was the first instance of the disease in California since 2015.
Prior to that, the most recent US case was in July in Colorado, where the patient did not survive. That same month, an unidentified resident in Arizona also succumbed to pneumonia-related plague, the first death in the state since 2007.
Colorado and New Mexico recorded plague cases last year, with a New Mexico patient being the first to die from the disease since 2020 and a Colorado case marking the state’s first death since 2007.
Typically, the US sees about seven cases of plague each year, which is a stark contrast to historical pandemics like the Black Death, which claimed millions across Europe.
Current plague cases are rare, mostly occurring in the Four Corners region (New Mexico, Arizona, Colorado, Utah) where conditions favor rodent and flea populations. Without treatment, the mortality rate can be between 30 to 60 percent, and if it reaches the lungs or bloodstream, it approaches nearly 100 percent.
Symptoms usually present within one to eight days and include fever, chills, and extreme fatigue, often accompanied by swollen lymph nodes. If untreated, the infection can escalate, leading to severe outcomes.
Recent data showed that 45 ground squirrels or chipmunks in the Lake Tahoe Basin had evidence of plague exposure from 2021 until now. Modern medicine has made significant strides, but the disease continues to exist in wildlife.
Health experts are advising caution in affected areas, recommending protective measures like wearing long pants and using bug repellent. They also emphasize not feeding or touching wild rodents and avoiding camping near burrows or dead animals.
