You hear "bubonic plague" and your brain probably goes straight to 14th-century Europe, wooden carts, and those terrifying bird-beaked masks. It feels like ancient history. But in late 2024 and early 2025, the conversation shifted back to reality when a resident in South Lake Tahoe tested positive for the disease.
Yeah, the actual plague. In California.
Honestly, it’s not a "outbreak" in the way Hollywood movies portray it. But for the person who spent their summer camping in El Dorado County only to end up with a high fever and swollen lymph nodes, it was very real. Health officials confirmed the case in August 2025, but the exposure—linked to the 2024-2025 season of heavy rodent activity—has a lot of people asking if they should be worried about their next hiking trip.
The Lake Tahoe Case: What Really Happened?
It started with a camping trip. The individual, whose name wasn't released for privacy, was likely bitten by an infected flea while enjoying the outdoors in the South Lake Tahoe area. This wasn't a case of "city rats" or poor hygiene. It was nature doing what nature does in the Sierras.
Kyle Fliflet, who serves as El Dorado County’s acting director of public health, was pretty blunt about it. He noted that plague is simply "naturally present" in many high-elevation parts of the state. Basically, the bacteria ($Yersinia$ $pestis$) has been living in the soil and the local rodent population for decades.
Between 2021 and 2024, state surveillance teams found 41 different rodents—mostly ground squirrels and chipmunks—that showed evidence of plague exposure in El Dorado County alone. By the time this human case popped up, the groundwork was already laid. The patient did the right thing: they sought medical care early, got started on antibiotics, and recovered at home.
Bubonic Plague California 2024: Is This a New Trend?
No. But it is a reminder.
California doesn't see many human cases. Before this, the last one in El Dorado County was back in 2020. Before that? You have to go back to 2015, when two people were exposed in Yosemite National Park. It’s rare. Like, "getting struck by lightning" rare. But the risk is constant because of the wildlife.
The 2024-2025 season saw a bit of a spike in animal detections. In 2025, four more rodents tested positive in the Tahoe Basin within just a few months. When you have a lot of snow or rain (like California has seen recently), the vegetation grows like crazy. More food means more squirrels. More squirrels mean more fleas.
More fleas mean a higher chance one of them is carrying $Y. pestis$.
Why the "Black Death" name is kinda misleading today
In the 1300s, the plague killed 25 million people because they didn't have Ciprofloxacin or Gentamicin. Today, we do. If you catch it early, it’s basically just a really aggressive bacterial infection that clears up with a standard round of meds. The "black" part of the Black Death refers to gangrene—tissue death—that happens when the bacteria gets into your blood and you don't treat it.
If you're reading this and you've got a fever after a hike, don't panic. But maybe call your doctor.
How People Actually Get It (It's Not Just Rats)
Most people think of rats. In the Sierras, it’s the cute stuff.
- Ground Squirrels: They are the primary reservoir.
- Chipmunks: They look like Disney characters, but they carry fleas.
- Your Cat: This is the one that actually scares veterinarians.
Cats are highly susceptible to plague. If your cat hunts a chipmunk that has the plague, the cat can get sick. Even worse, if the cat develops the pneumonic version of the plague, they can cough infectious droplets directly onto you. That is the only version that spreads person-to-person (or cat-to-person). In early 2024, a person in Oregon actually caught the plague from their pet cat.
It’s a weird, circular ecosystem. The flea bites the squirrel, the squirrel gets sick, the flea jumps to your dog, the dog brings the flea into your tent, and the flea bites you.
Spotting the Symptoms: Buboes and Beyond
The hallmark of the bubonic plague is the "bubo."
It’s a swollen lymph node. Think of it like a golf-ball-sized lump in your groin, armpit, or neck. It’s usually incredibly painful and tender to the touch.
Other symptoms look a lot like a bad flu:
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- Sudden high fever (we're talking $103^{\circ}F$ or higher).
- Chills that make your teeth chatter.
- A headache that feels like a sledgehammer.
- Extreme exhaustion.
If the bacteria moves from the lymph nodes into the blood, it becomes septicemic plague. This is much more dangerous because it can cause internal bleeding and that "blackening" of the fingers and toes. If it hits the lungs, it's pneumonic plague, which causes a bloody cough and can be fatal within 24 hours if you don't get the right drugs.
Lessons from the 2024 Detections
The California Department of Public Health (CDPH) isn't just sitting around. They regularly test "sentinel" animals and trap fleas in popular campgrounds like Richardson’s Beach or Fallen Leaf Lake. If they find a hot spot, they’ll literally "dust" rodent burrows with insecticide to kill the fleas.
But they can't dust the whole mountain range.
What we learned from the bubonic plague California 2024 surveillance is that the bacteria is moving. It’s not just in one meadow. It’s shifting with the rodent populations. This is why you see those yellow signs at trailheads telling you not to feed the squirrels.
It’s not because the Forest Service is mean. It’s because if you feed a squirrel, you’re putting your hand right next to a potential colony of $Y. pestis$ fleas.
Actionable Steps for Your Next Trip
You don't need to cancel your Tahoe vacation. You just need to be smart.
Use the right repellent. DEET is your best friend here. Spray it on your socks and pant cuffs. Fleas aren't great jumpers; they usually hitch a ride from the ground or low-hanging brush.
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Tuck your pants. It looks dorky, but tucking your pants into your socks creates a physical barrier. If a flea lands on your sock, it can't get to your skin.
Keep the dog on a leash. If your golden retriever runs into a colony of ground squirrels and starts sniffing around their burrows, he’s coming back with "hitchhikers." Use a vet-approved flea treatment before you go.
Don't touch dead stuff. If you see a dead squirrel on the trail, leave it alone. As soon as a rodent dies and its body cools down, the fleas leave the carcass to find a "warm" host. That host could be you.
Watch your symptoms. If you’ve been in the Sierra Nevada foothills or mountains and you develop a fever within 7 days of coming home, tell your doctor. Specifically mention that you were in a plague-endemic area. Most doctors in cities like San Francisco or LA won't even think to test for plague unless you tell them where you've been.
Plague in 2026 isn't a death sentence. It’s a manageable risk. As long as we stop treating squirrels like pets and start treating them like the wild animals they are, the "Black Death" stays where it belongs—in the history books and the occasional, very treatable, news headline.