Bears, Noro, and Lyme: What to Worry About (or not) on Your Thru-Hike

So, you’re planning to head out on trail for a long walk. Maybe even a thru-hike of one of the Triple Crown trails — the Appalachian Trail, Pacific Crest Trail, and Continental Divide Trail.

You’ve probably gotten a lot of questions from people who think you are out of your mind, many of which begin with, “Aren’t you afraid of…”

Veteran thru-hikers will tell you that while there are inevitable dangers on trail, stereotypical fears are usually overblown. Here’s a hard look at three common concerns on the trail—bears, Lyme disease and norovirus—how much you should (or shouldn’t) worry about them, and how to minimize their impact on your hike.


Image via

Let’s start with the bugaboo that friends and family fret about when they imagine you—a tasty human hors d’oeuvreout in the wild for six months.

Bears are a fact of life on all three Triple Crown trails. The American black bear (Ursus americanus) is common on all three trails, while the brown bear, aka grizzly (Ursus arctos) is found only near the northern reaches of the CDT. If you see a polar bear, Ursus marinus, you’re either taking a zero in a city with a zoo or considerably off course.

Grizzlies and black bears were once hunted to near extinction. Today they are thriving, with as many as 465,000 black bears and 200,000 grizzlies (mostly in Canada and Alaska) roaming the continent.

So, how dangerous are they? Here’s a clue: Most long-distance hikers consider bear sightings a highlight, not a nightmare. Consider these stats:

  • Between 2000 and 2019, there have been just 53 documented fatal attacks on humans by bears in North America, or about 2.8 per year.
  • Of those, just ten fatal grizzly attacks and 10 fatal black-bear attacks occurred in the Lower 48, or about one per year.
  • No fatal grizzly attacks occurred in states traversed by the AT; one occurred in a PCT state (California, but with this notable asterisk: a captive bear killed its handler); nine were in CDT states.
  • Of CDT-state grizzly attacks, six occurred in Yellowstone National Park (around four million annual visitors) or Grand Teton National Park (around three million annual visitors).
  • Of fatal black-bear attacks, four occurred in AT states, two were in CDT states, and none were in PCT states.
  • No fatal black-bear attacks occurred on the AT, PCT, or CDT. The two CDT-state black-bear attacks occurred far from the trail. Of the AT-state attacks, two occurred about ten miles from the trail (one in the Smokies; the other was the first recorded bear fatality in New Jersey history); the other two were at least 50 miles from the trail.

There is no reliable data on nonfatal attacks on or near Triple Crown trails. But considering the millions of people who annually visit some part of the trails — the Appalachian Trail Conservancy estimates that more than two million people visit the trail every year, for example, and some seven million people a year visit Yellowstone and Grand Teton national parks, traversed by the CDT — your chances of a dangerous bear encounter are vanishingly small, considerably less than one in a million. Statistically speaking, you’re about 60,000 times more likely to be killed by a human than a bear.

That said, it pays to be bear-smart.

  • The ATC now recommends that hikers carry food in a bear-resistant container approved by the International Grizzly Bear Committee. Canisters are required on significant portions of the PCT and CDT.
  • Learn how to properly hang a bear-bag. (Dangling a non-bear-proof bag from a spindly limb four feet from the ground does not count.)
  • Prepare and eat food away from your sleeping quarters.
  • Keep your dog in check. One study of black-bear attacks found that more than half involved an off-leash dog.
  • Educate yourself of how to respond if a bear does attack.

Conclusion: Be bear-smart, but your chances of having a negative encounter with a bear are extremely low, bordering on non-existent.

Lyme Disease

A black-legged, or deer, tick. I hate them all with a passion. Photo: Wikimedia Commons

If you are a CDT or PCT hiker, you’re mostly off the hook for this one, as incidence of Lyme disease is negligible in the West (though it is rising faster in California than in any other state except Florida).

But if you are an AT hiker, Lyme disease should concern you much more than bears. Believe it or not, one out of every 20 AT thru-hikers will contract this tickborne disease in 2019.

In fact, the AT passes through ten of the 15 states with the highest Lyme incidence (cases per 100,000 residents), according to 2017 statistics compiled by the Centers for Disease Control. The worst state may surprise you: Maine, with 1,850 cases, or 106 per 100,000 residents. But number three Pennsylvania is tops in raw numbers, with a whopping 11,900 cases, more than twice as many as the next two contenders, number 13 New York (5,155 cases) and number seven New Jersey (5,092). These AT states also rank in the top 15 for cases per 100,000 residents: number two, Vermont (1,092 cases); number five, New Hampshire (1,381); number six, Connecticut (2,051); number 11, Maryland (1,891); number 12, Massachusetts (410); and number 14, Virginia (1,657). Lyme disease is considerably less common in southern AT states so far — in 2017, 45th-ranked Georgia reported just 0.1 cases per 100,000 residents; Tennessee (0.2) was 42nd, and North Carolina (0.7) was 26th — but bites from the lone-star tick, Amblyomma americanum, can cause STARI, or southern tick-associated rash illness, which can cause similar symptoms.

cdc lyme disease appalachian trail

Map of incidence of Lyme disease, 2017. AT hikers take note of dark blue areas from Virginia to Maine. Centers for Disease Control.

Lyme disease is a very specific disease: It is an infection caused by the bacterium Borrelia burgdorferi, which is carried by the black-legged tick, aka deer tick (Ixodes scapularis). The early signs of an infection are a lot like flu symptoms, including:

  • Fever
  • Chills
  • Headache
  • Fatigue
  • Muscle and joint aches
  • Swollen lymph glands

And in an estimated 70 to 80 percent of cases, according to the CDC, an erythra migrans rash may be present — which means that 30 percent or more people may not show the rash. The rash may appear anywhere on the body. It is not always present, may take up to 30 days to appear and frequently does not appear in the classic bulls-eye pattern.

lyme disease appalachian trail

Possible erythra migrans rash, taken in emergency room in Reading, PA. Clay Bonnyman Evans photo.

If caught early, Lyme disease is easily treated with common antibiotics such as Doxycycline and Amoxicillin. If left untreated, Lyme can cause serious, even life-threatening symptoms, including heart disease and partial paralysis. You do not want to mess around with Lyme.

But here’s the catch: the disease cannot be definitively diagnosed, even through laboratory tests, for up to six weeks.

“Antibodies against Lyme disease bacteria usually take a few weeks to develop,” according to the CDC. “During the first few weeks of infection, such as when a patient has an erythema migrans rash, the test is expected to be negative.”

Another bummer: The ticks most likely to transmit the disease are in the nymphal stage. They are teeny-tiny little pests, the size of a poppy seed or even smaller. Hard to find.

But don’t worry: Doctors in Lyme-endemic states are hip to all this. Rejected by a doc-in-a-box clinic because my fever was “too high” (104 degrees), I staggered into an emergency room in Reading, PA, during my 2016 AT thru-hike. There, the no-nonsense doc swiftly prescribed doxycycline based on a) my symptoms (including a non-bulls-eye rash) and b) circumstances, i.e., living in the woods and infrequently showering. It sucked, but after a few days of misery, I was on my way north.

You may have heard stories of a debilitating, ongoing illness called “chronic Lyme disease.” The CDC is skeptical of this alleged diagnosis, preferring the label “Post-Treatment Lyme Disease Syndrome.” The agency cautions that some treatments prescribed by doctors for the syndrome, including prolonged courses of antibiotics, are not effective and can cause long-term complications.

Your best bet, of course, is to avoid contracting Lyme (or STARI) in the first place. Here are a few good rules recommended by the ATC.

  • Wear clothes treated with permethrin. You can buy pre-treated clothes, spray them yourself or even send your gear to be treated by a company called Insect Shield.
  • Wear long pants and sleeves in tick territory. (Confession: Even after suffering the symptoms of Lyme, I couldn’t bear wearing long sleeves and pants while trudging through the mid-Atlantic inferno in high summer.)
  • Wear light-colored clothing.
  • Apply Deet-based insect repellent to exposed skin.
  • Do tick checks nightly. Recruit a pal to check, uh, the areas you can’t see yourself; make sure he or she is a really good pal, since the tiny nymphal ticks most likely to transmit Lyme are very hard to see.
  • Ask your doctor if she will prescribe a course of doxycycline or Amoxicillin prior to your hike. If you develop flu-like symptoms, take the antibiotics as prescribed, and you’ll save yourself the hassle and cost of going to a doctor who will simply prescribe the same medication.

Conclusion: Lyme-bearing ticks are be a lot smaller than a bear—800 million times smaller—but they should take up much more of your concern.


Norovirus sucks as much as black-legged ticks. Photo: Wikipedia Commons.

This nasty little bug is millions of times smaller than a tick, but it frequently causes distress and suffering among long-distance hikers.

Noro, as it is often referred to, is a tiny viral particle that causes diarrhea and vomiting. The most common cause of acute gastroenteritis in the United States, noro annually causes up to 71,000 hospitalizations and 800 deaths. It’s a tenacious little bugger that can survive on a dry surface for weeks.

There aren’t good statistics about the incidence of noro on trails — but the ATC typically puts out several noro warnings each year for AT hikers. It’s a people thing: the more crowded the trail, the more likely it is that the disease will be present. Suffice it to say that it’s common, and all-too-easy to contract by:

  • Having direct contact with an infected person.
  • Consuming contaminated food or water.
  • Touching contaminated surfaces, or consuming food that has touched contaminated surfaces.
  • “You can get norovirus,” according to the CDC, “by accidentally getting tiny particles of poop or vomit from an infected person in your mouth.” Yum.

Symptoms usually develop 12 to 48 hours after exposure and the illness usually runs its course in one to three days. Disturbingly, people may continue to “shed” the virus for up to two weeks.

Instead of a gross illustration of norovirus, here’s a shot looking up from the bottom of Mahoosuc Notch in Maine. Clay Bonnyman Evans.

It’s hard not to be filthy on trail — it’s part of the fun, right? But there are plenty of things you can do to reduce the likelihood of contracting a nasty case of noro on the trail.

  • Wash your hands, early and often. With soap and water (at least 200 feet from any water source). Antibacterial hand sanitizer isn’t as good as washing, but it’s better than nothing.
  • Don’t share food, water bottles or utensils.
  • Don’t shake hands. Fist bumps are not just an affectation!
  • Properly treat water.
  • Follow Leave No Trace guidelines for disposal of human waste.
  • Report outbreaks or incidence of norovirus. Email [email protected] to help the ATC notify hikers of outbreaks.

Conclusion: Norovirus is small—millions of times smaller than a bear or tick—but it’s brutal, and can cause miserable havoc on trail. You have a right to be worried about it, and don’t forget to wash your hands!

Featured image via 

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Comments 9

  • Marcia E Herman : Feb 27th

    Regarding Lyme in the southern part of the AT: I think calling it “exceedingly rare” is an overstatement. “Far less common” might be a better way of putting it. The incidence is growing in the SE. gets calls from people on the AT in NC who have gotten sick. Plus, as you no doubt know, it cannot be diagnosed with tests in the first couple of weeks so can’t be distinguished STARI at first. Lone star ticks are not as common in NC mountains as the black-legged tick. Both of these ticks may carry other human pathogens in addition to Lyme. And regarding that so-called target rash: some studies have shown the incidence at being lower, around 50%, and studies have found it is most commonly solid red, especially in the beginning. It is important for hikers to have sharp-pointed tweezers and know proper removal technique to lessen chance of infection.

    • Clay Bonnyman Evans : Feb 27th

      Thanks for the response, Marcia, and for being a careful reader.

      I agree that “exceedingly rare” is probably too strong, so I’ve updated the story with new language.

      I’ve also included some data points for incidence of Lyme in Georgia (0.1 cases per 100,000 residents, 45th out of 50 states), Tennessee (0.2; 42nd) and North Carolina (0.7; 26th).

      I’ve also updated the language regarding erythra migrans to indicate that the stats I cite are CDC estimates.

      Please be advised that changes must be approved by the editor before they show up online.


  • Carolyn Suddaby : Mar 7th

    While some doctors may be “hip” to Lyme disease in some areas, they are greatly lagging in others. I live in N.C. where Lyme disease is on the rise, higher than CDC models, as they cherry pick test results. My daughter got Lyme in N.C. and as we were ignored by the medical community to her symptoms, especially because she was one of the 30% not to get the bullseye rash, thus refusing to test for Lyme, they would just say it was all in her head. By the time I could get her tested, and it was positive, it was too late to treat effectively. So I take issue with your statement of belittling chronic Lyme. The Lyme bacteria is corkscrew shaped and drills easily into organs, joints, heart, brain and central nervous system, hiding in places where antibiotics can not reach. The bacteria will also make cysts and hide in them when there is a threat against them, antibiotics, only to burst open when the threat is gone, reinfecting its host.
    You are very lucky you got treated right away. Lyme has ruined my daughters life.

    • Clay Bonnyman Evans : Mar 8th

      I’m very sorry to hear about your daughter’s struggles with Lyme disease. As I’ve written, and experienced, it’s nothing to mess around with.

      I don’t think this piece belittles the danger of acquiring Lyme disease, or downplays the importance of early treatment. Regarding “chronic Lyme disease,” the CDC is skeptical of this diagnosis, for which there has been no reproducible or convincing scientific evidence, but the agency does acknowledge “Post-Treatment Lyme Disease Syndrome” ( The key issue is disagreement with certain practitioners’ diagnosis of “chronic Lyme” who prescribe long-term courses of antibiotics, which, according to the research, may even be harmful; often, this treatment is given to people based on symptoms who never test positive for Lyme.

      In your daughter’s case, I’m very sorry that doctors did not pre-emptively prescribe Doxycycline or Amoxicillan, based on her symptoms and circumstances. This is a non-controversial approach to knocking back the spirochete in its early critical, early stages, when in fact it is still not detectable via titration.

      If anyone takes anything away from the section on Lyme disease above, it should be: If you are in the woods and experience the symptoms (no rash necessary!), find a doctor immediately who will prescribe a 14- to 21-day course of the antibiotics mentioned and take the full course, even after you are feeling better. Anyone, including doctors, who belittles the reasonable possibility that the disease is present in its early, non-diagnosable stages can set up a patient for horrendous consequences down the road.

  • Sara : Mar 13th

    As a hiker and as someone whose life has been devastated by 10 different tick borne diseases I can say that there is A LOT of dangerous misinformation in this article.

    Due to the CDC/IDSA conflict of interests, their reporting is misleading and inadequate. For updated awareness, proper treatment guidelines, and overall correct information check:

    Lyme Disease exists in every part of this country. 50% of a US counties now harbor ticks that carry Lyme and many other dangerous tick borne diseases.

    Lyme Disease carrying ticks exist in the continental divide region.

    Doxycycline has recently been proven to NOT eradicate the Lyme Disease spirochete.

    • Clay Bonnyman Evans : Mar 15th


      I realize that there is some controversy over what some people call “chronic Lyme disease,” but to my knowledge, the CDC provides reliable, up-to-date, unbiased information on its web site.

      If you have specific evidence — not assertions — to demonstrate that the CDC has a “conflict of interest” that would lead its scientists to (for some reason) not provide accurate information regarding Lyme disease, I’d be interested in seeing it.

      The piece does not say, incidentally, anything about the incidence of Lyme in states that are not traversed by the AT. However, it seems to me that the map of 2017 reported incidences is sufficient to show that yes, the disease does appear in all states, only at significantly reduced rates in some than others.

      Thanks for writing.

  • Vanita Singh : Jun 8th

    Where to look for Permethrin-treated clothes?
    Search for industry-wide credentials first. This apparel domain is still developing. There are not many quality standards to compare. But you should know a few things. Firstly, commonly-available insect-repellent clothing is made to withstand just about 40 regular washings. Further, not all permethrin-treated clothes provide the protection expected – the fabric treatment is not comprehensive enough. You need a brand that allows for maximum number of washes and promises efficient performance in the worst climatic conditions. BugShield Clothing provides permethrin-treated clothing developed with Insect Shield Technology, meeting international standards. This line of apparel assures performance demanded by the armed forces and rescue groups working in the toughest outdoor conditions.

    Making Smarter Buying Decisions
    BugShield Clothing apparels can be trusted to last up to 70 washes without any reduction in the of insect-protection performance. These permethrin-infused garments can safeguard your children from dangerous insect-borne diseases such as malaria, West Nile virus, dengue fever, and chikungunya. Ready to use off-the-shelf, these garments provide everyday-wear and fashion-wear options for kids and the entire family!


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