Officials warn of an ‘unprecedented’ risk of the plague in US travel hotspots

Travelers in the US are being warned about an ‘unprecedented’ risk of the plague as rodent numbers explode across the country. 

Earlier this year, researchers at the University of Richmond blamed rising temperatures and urbanization for an increase in infestations. 

Looking at cities around the world, they found the US saw some of the highest upticks in rodent populations, with Washington the leader in rat increases, followed by San Francisco, Toronto and New York City. 

Rodents can be carriers of the plague bacteria (Yersinia pestis) and can transmit the deadly disease to humans through flea bites or direct contact with infected animals. 

Lake Tahoe in California – which receives more than 15million visitors a year – has already reported two cases of the disease with record number of vermin this year.

Eric Brooks, a writer who recently traveled to Lake Tahoe with his family, said before they arrived at their vacation property, they received an email informing them that there was a ‘surge in mouse activity’ in the area and hardware stores had run out of traps.

The notice, from Agate Bay Realty Lake Tahoe, revealed that it had five properties in its portfolio plagued by rodent infestations, but these situations were being remedied. 

Brett Williams, its broker and owner, went on to reveal that pest controllers he works with who have been in the business for around 40 years, have deemed it the ‘year of the mouse’, due to the numbers being so rampant. 

From 2021 to 2024, 41 rodents tested positive for plague in the Tahoe Basin area within El Dorado County, and an additional four tested positive in 2025, totaling 45. 

Off the back of the outbreak, one visitor who was camping in the area this summer contracted the plague but they recovered after receiving medical care. 

In a piece for SF Gate, Brooks revealed he visited a few hardware stores around Lake Tahoe, with workers describing the same trend – booming sales for rodent traps and poison, leading to a run on supplies.

One staff member told him: ‘We get cleared out by the end of the day. Everyone in town is going through the same thing right now.’

And at North Shore Ace Hardware in Kings Beach, assistant manager Maurice Jacques revealed locals haven’t seen anything like it in 15 to 20 years.

He explained: ‘We’re been upping our orders on mouse traps, really anything to do with mice or rats. 

‘We get trucks two times a week. By Saturday, we’re all out. Some people come in and buy 15 traps at a time.’ 

Sergio Arias, of Tahoe Pest Management, said that the rodent problem started surfacing in March, and by the summer months it was surging. 

He told SF Gate: ‘This year has been out of this world crazy busy for these rodents.

‘It’s highly unusual. I have other buddies in the industry. They say, “I can’t keep up.”‘

He said he now gets up to 60 calls a week and visits anywhere from eight to 15 homes per day to eradicate the rodents.

Previously, he might have handled around 20 incidents a month.  In one recent call-out, he said he pulled 70 rats out of one house. 

He added: ‘That’s not even the worst I’ve seen. The worst was a vacant home. I think we pulled something like 150 rats out of this home. 

‘They’re chewing through siding. They’re chewing through the wood on people’s homes to get into the walls.’

A person from Lake Tahoe tested positive for the Black Death in August after being bitten by an infected flea while camping.

California health officials said at the time the person was under the care of a medical professional and was recovering at home. 

It marked El Dorado’s first confirmed case of the plague since 2020, which was also believed to have been transmitted in the South Lake Tahoe Area. Prior to that, the disease had not been detected in California since 2015.

The most recent US case prior to that was in July, in Colorado. That patient did not survive. 

And the same month, the plague was also detected in Arizona when an unidentified resident became the state’s first death from the disease since 2007.

The resident’s cause of death was pneumonic plague, the most dangerous form of the Black Death, which spreads by inhaling droplets of saliva emitted from an infected person or animal coughing or sneezing.

Colorado and New Mexico also recorded plague cases last year. The New Mexico patient was the first to be infected with and die of the plague since 2020. Colorado’s was the state’s first death since 2007. 

Just seven cases of the plague are reported on average in the US each year, according to the CDC.

This is a significant reduction when in medieval times the plague, sometimes referred to as the Black Death, wiped out 25 to 50million people in Europe. This was thought to be 30 to 50 percent of the population. 

Plague cases in the US today are rare, with fewer than ten every year. They mostly occur in the Four Corners region (New Mexico, Arizona, Colorado, Utah), where rodents and fleas thrive. 

Untreated plague has a mortality rate of 30 to 60 percent in the US. But if it spreads to the lungs or bloodstream, it’s nearly 100 percent deadly. 

Plague symptoms strike within one to eight days, with fever, chills, and debilitating fatigue. 

It’s often accompanied by painful swollen lymph nodes in the groin or armpits. Left untreated, it can enter the bloodstream and travel to the lungs, causing deadly infections. 

Once the disease enters cells, it kills them by releasing deadly toxins. 

Infection can arise from handling infected cats, rodents, or their fleas.

According to the California Department of Health, there were 45 ground squirrels or chipmunks with evidence of exposure to the plague bacterium in the Lake Tahoe Basin from 2021 to 2025.

Modern antibiotics and hygiene have drastically reduced deaths, but the disease remains endemic in wildlife. 

Health officials urge caution in high-risk areas.

They recommend wearing long pants tucked into boots and using a bug repellent with DEET.

Additionally, people in the area should never feed or touch wild rodents and refrain from camping new animal burrows or dead rodents.