Ticks can transmit 18 different pathogens to humans, including Lyme. Photo: Erik Karits//Unsplash
Estimates say about half a million people contract Lyme disease annually in the U.S. Outdoors enthusiasts are on the front lines for contracting the tick-borne bacteria.
And it’s not just hardcore thru-hikers contracting Lyme. Celebrities such as Justin Bieber and Bella Hadid have revealed they have the disease, and surf prodigy Sierra Kerr announced late last year that Lyme disease kept her out of the water for several months.
While researchers have learned a lot about the disease since it was officially classified in 1978, there is still a lot that perplexes experts: symptoms vary, many patients go undiagnosed, and some respond well to treatment, while others experience long-term symptoms.
According to Jo Ellis, Director of Education at Bay Area Lyme Foundation, “you just have to be tick aware wherever there is grass and nature.” In other words, hikers, campers, mountain bikers, surfers trudging through the bush to get to a wave: be aware.
To demystify the causes, risks, symptoms, and prevention methods, we spoke with Ellis, Dr. Daniel Cameron, an expert on Lyme and tick-borne diseases, and Dr. Janet Foley, a professor at UC Davis Weill School of Veterinary Medicine, to help you play safely no matter what you’re doing out there.
Jump to:
How do you get Lyme?
How long after a tick bite does it take to contract Lyme?
Where did Lyme come from?
Where are you most likely to get Lyme?
How can you avoid a tick bite?
How should you remove a tick once it’s latched on?
What are the symptoms of Lyme?
Is Lyme curable?
Can Lyme be transmitted between humans?
How do you get Lyme?
Lyme disease is a bacterial infection caused by Borrelia burgdorferi, which spreads to ticks when they feed on small mammals — such as squirrels and mice — or birds. Attracted to the carbon dioxide that we breathe, ticks then feed on humans and transmit the infection to us.
Female ticks do not pass the bacteria to their offspring, although they can pass on other pathogens, such as Rocky Mountain spotted fever. Deer do not contract Lyme disease. However, deer are a source of sustenance, and ticks can be found where they live.
Within the United States, the western blacklegged tick is the culprit for spreading the bacteria on the West Coast, while the similar eastern black-legged tick — aka deer tick — spreads it on the East Coast.
How long after a tick bite does it take to contract Lyme?
While the CDC’s position is that, in general, the tick must be attached to a human for at least 24 hours to transmit the bacteria, Ellis and Cameron caution that there are many unknowns with transmission time.
“That CDC position is mostly based on mice studies,” said Cameron. “I don’t think that there’s a consensus in the Lyme community. In actual practice, there are people who become ill in less time than that. It helps to get (the tick) off, but I’m not convinced (of the 24-hour timeframe) based on my practice.”
Cameron also notes that ticks can transmit other viruses and bacteria. It’s possible to get more than one from a single bite, or one or the other. The Powassan virus, for example, can transmit in 15 minutes, he said.
Cameron still stresses that the sooner you remove the tick, the better. If the tick has enough time to gorge itself with blood, the chances of contracting Lyme increase.
“In the northeast, there’s a 20 percent chance that an engorged tick will give you something, Lyme, or maybe a coinfection,” Cameron said. “So if you get it off before it’s gorged, that’s better, but I still wouldn’t want any tick to bite me.”
Experts say the sooner you can get the tick off, the better. Photo: Erik Karits//Unsplash
Where did Lyme come from?
The disease is named after the town of Lyme in Connecticut, where, in 1975, a group of people was suffering mysterious arthritic symptoms. It turned out to be Lyme. Advocates in this group conducted research and worked with scientists to classify the disease. The first confirmed case of Lyme in California was in 1978.
However, Lyme has likely been among humans for much longer without an official name or diagnosis. A Stanford report says that a 5,300-year-old mummy discovered in the Italian-Austrian Alps possibly had Lyme bacteria. So, while in modern times the disease has been focused in the United States, particularly the East Coast, it’s not a new phenomenon.
Subsequent research in the 2000s greatly improved our understanding of the disease, how it’s contracted, and how it can be treated. But there is still much to learn.
Where are you most likely to get Lyme?
In theory, humans can contract Lyme in any habitat that provides a meal for ticks. Cameron says that anywhere with ground cover is prime tick habitat. In areas without cover, there is less habitat for mammals that ticks like to feed on, like mice.
Ellis says no one ecosystem houses ticks. Ticks are found almost anywhere you interact with nature. Oftentimes, it’s in domestic settings, where people have their guard down, that they end up contracting the disease. She says that they see many cases that come from gardening, playing in parks, playing golf, or dogs bringing them into the home.
“A tick in the yard is worth two in the bush” is a saying in the Lyme disease medical community, Cameron said, underlining that people are less vigilant when performing routine activities like mowing their lawn versus hiking.
While Ellis notes that there is still much research to be done on where ticks live, particularly those that carry Lyme, generally speaking, it’s rare to find ticks at high altitudes. There are only three counties in California where the western blacklegged tick has not been found: Alpine, Modoc, and Mono — all counties with relatively high elevations. (The ticks may exist there, they just haven’t been recorded.)
That said, she stresses that tick populations with Lyme can vary greatly, even within the same microhabitat. Lyme-infected ticks have been discovered in 42 of 58 counties in California, and while confirmed cases tend to be centered on the East Coast, Ellis notes that this doesn’t mean Western ticks carry the disease in smaller numbers. When you factor in the 18 diseases that ticks can simultaneously transmit, including Lyme, she says, infection rates on the West Coast approach those on the East Coast. And, importantly, tick season is year-round in California due to the mild climate.
Lyme cases have also been confirmed in 65 countries.
“It depends on what you go out and look for,” she said. “If you send ecologists out, they’re going to be investigating and collecting ticks in sections of trails. But infection rates can be wildly varied from one section of trail to another, even within the same park.”
“It’s not possible to know exactly where those hot spots are from season to season or year to year, because of the dynamism in the chain and the life cycle of the ticks,” she added.
Habitats with cover for small mammals provide prime feeding sources for ticks. Photo: Evan Quarnstrom
How can you avoid a tick bite?
Cameron and Ellis recommend several techniques to mitigate the risk of getting bitten:
- Wear light-colored clothes so ticks can be more easily spotted.
- Wear pants and long sleeves, tucking your pants into your socks if possible.
- Check for ticks regularly during and after a nature experience: pay special attention to the scalp, where ticks can hide in hair.
- When you get home from the outdoors, throw your clothes into the dryer. This will kill or remove ticks from clothing. They can survive a machine wash and remain on your body after a shower if they have already latched on.
- Don’t let pets that could be carrying ticks into your bed.
- Treat fabric (clothing, tent, sleeping bag, etc.) with Permethrin.
- Wear insect repellent with at least 20 percent DEET. Alternatives for DEET include lemon eucalyptus oil or natural repellents.
How should you remove a tick once it’s latched on?
When a tick bites you, it punctures the skin with its barbed mouthparts and injects an anesthetic, adhesive, and anti-coagulant so the blood continues to flow. That’s why those who are bitten often don’t notice. And once a tick has latched on, it can be difficult to remove.
Ellis recommends using fine-tip tweezers to remove the tick because flathead tweezers risk snapping the head off.
“Very gently, but firmly, pull the tick straight up away from the skin, and don’t twist it,” she said. “Don’t yank it because you don’t want to shock the tick.”
If you shock the tick, it may regurgitate the contents of its midgut, which is where the pathogens are found.
“That’s one of the reasons it’s very important to tick-check very thoroughly every time you come in, when you’ve been outside bushwhacking, horseback riding, trail biking, trail running, whatever you’ve been doing,” she said. “You want to get those ticks off of yourself as quickly as possible.”
Long sleeves, long pants, and light-colored clothing are a few ways to mitigate the risk of a tick bite. Photo: Evan Quarnstrom
What are the symptoms of Lyme?
Lyme disease can be a mystery due to several factors: the symptoms are not uniform or may be absent altogether, tests are not reliable, infected people may never realize a tick bit them, and ticks can transmit other pathogens along with Lyme. As a result, Cameron pointed out that even the CDC acknowledges the true extent of Lyme cases may be as much as 10 times higher than the number of confirmed cases.
Cameron explained that the classic signs of Lyme include swollen knees and joints or a rash with a “bullseye.” However, Cameron noted that only about half of infected patients get a rash, and of those rashes, only a quarter form the bullseye shape. As a result, many patients don’t realize they are infected and go undiagnosed. Only one in five will ever see the tick that bit them.
More serious symptoms are neurological, like fatigue and migraines. The body’s reaction to fighting the infection can have many cascading secondary symptoms, like hypertension, poor sleep, anxiety, mood swings, numbness in the hands and feet, and stomach issues.
Cameron said he’s seen patients who are sent off to several specialists to seek help for each problem, not realizing that Lyme is the root cause. He noted that it’s difficult to test for Lyme disease because the bacteria are similar to natural bacteria found in the human body.
“It’s hard to find a clean blood test that tells you what’s normal and what’s not,” said Cameron, saying that it’s much easier to detect a virus in the blood because they aren’t natural. “The treatment is trying to treat something close to your own body.”
According to Dr. Peter Gwynne, a microbiologist studying Lyme disease, current tests for early detection are so unreliable that they’re often ineffective, making it difficult to determine who actually has the disease. Insurance companies may also rely on these imprecise tests to deny coverage.
“In the first week of infection, the existing tests detected about five to 10 percent of cases,” Gwynne said. “That’s functionally useless. The newer test detected about 30 percent.”
Dr. Foley notes that, while some patients with Lyme go undiagnosed, on the other hand, there are others convinced they have Lyme when they do not.
“There are patients who really have chronic pain and inflammatory disease and believe they have Lyme, but all the tests come back negative,” Foley said. “I genuinely try to keep an open mind, but we’ve learned so much with COVID and other diseases that disrupt our immune systems, so I imagine many of these patients are genuinely sick but not necessarily with Lyme.”
Additionally, Cameron said it’s possible to get infected with more than one type of bacteria or virus at once from a tick bite, making the root of the symptoms even harder to pinpoint.
Is Lyme curable?
“There are just so many complex factors, and still there’s a lot that we do not know,” Ellis said of treating Lyme disease.
Cameron notes that some patients respond well to antibiotic treatment, while others have recurring symptoms. This could be due to an undiagnosed secondary virus or bacteria, or the persistor theory, where a certain portion of the bacteria does not respond to treatment.
“Sometimes 10 percent or so of an infection just lingers and stays there,” Cameron said. “It’s not dividing, it’s not really doing much, but it’s still there and giving illness. That makes the most sense to me (as a theory).”
Foley adds that while Lyme isn’t generally considered fatal, there is ongoing debate in severe, chronic cases. In rare instances, it can affect the heart and brain, leading to cardiac complications that disrupt heart rhythm.
According to Cameron, other tick-borne viruses like Powassan are, in fact, responsible for a few deaths per year.
Cameron said that while some vaccines have been shown to prevent rashes, none are proven to stop chronic illness. Foley noted promising developments in tick vaccines that could kill ticks as they feed, an approach several labs are exploring.
The Bay Area Lyme Foundation notes research by Dr. Robert Lane at the University of California at Berkeley that shows the immune system of the western fence lizard destroys the Lyme bacteria. Further understanding this process could provide clues to create a vaccine for humans.
Can Lyme be transmitted between humans?
Humans probably can’t transmit the bacteria to one another, according to Cameron, but more data is necessary in this area to arrive at a definitive conclusion.
“I need more research before I think about that,” said Cameron. “I certainly have a lot of people who get sexually active (with the disease), and nothing happens. Somebody studied a dozen couples, but the research was not good enough to permeate, so I don’t consider it sexually transmissible, but you never know.”
Foley supports Cameron’s view, saying there’s no evidence that Lyme can be transmitted sexually, though rare outlier cases of human transmission can’t be entirely ruled out.
“Any cases of human-to-human are extremely rare but could be across the placenta or via corneal transplant,” Foley said.
Research is being conducted to see if or how a fetus can be affected if a pregnant woman carries the disease.
Don’t be paranoid, but be careful
Ellis and Cameron stress that you don’t need to be afraid of Lyme, but you should be aware, informed, and take preventative action when outdoors.
“We don’t want people to be paranoid because we live in such an extraordinarily beautiful place,” said Ellis. “We want people to be out there enjoying the outdoors.”
“You wouldn’t go out without a sufficient amount of water for your hike, right?” she added. “Well, we want people to be thinking about tick bite prevention, too. You stand a bigger chance of being bitten by a tick in the Santa Cruz Mountains, for example, than you do encountering a mountain lion or a rattlesnake.”
Cameron says everyone should at the very least get up to speed, because ticks can be anywhere: from a tree along a trail to your bedsheets.
“Even if you think ‘I’m never going to go out (in nature),’ you still have to be just as aware,” said Cameron. “You’re not free of having to be aware of Lyme.”
