Why tick-borne diseases have reached ‘epidemic proportions’
Infections have more than doubled in the U.S. since 2004, afflicting many patients with long-term memory problems, overwhelming fatigue, and even red-meat allergies.
Nicole Malachowski is a powerful woman. After graduating from the U.S Air Force Academy, she became an F-15E fighter pilot who flew missions in Iraq, commander of the 333rd Fighter Squadron, and the first female pilot in the elite Thunderbirds demonstration squadron. She is married and the mother of twins. In 2019 she was inducted into the National Women’s Hall of Fame.
Malachowski was a highly decorated “full bird” colonel when she was forced to leave military service due to health issues. But it wasn’t a combat injury that cut short her career: It was a tick.
At 43 years old “I was declared ‘100 percent unfit for duty’ and was medically retired,” she says. She was utterly debilitated: bedridden, housebound, barely able to stand, walk, or speak. “I thought I was tough, but I was completely broken.”
It took four years and 24 doctors to finally diagnose what proved to be a trio of tick-borne bacterial diseases—Lyme,anaplasmosis, and tick-borne relapsing fever—as well as a tickborne parasite, babesia. Malachowski partially recovered after doctors pumped her with antibiotics and anti-parasitic drugs, some delivered directly into her heart, and she had a year’s physical therapy.
While her case is extreme, it illustrates a growing public health concern: “Every year we've seen more tick-borne diseases in the United States ... and more people exposed to ticks,” says Charles “Ben” Beard, deputy director of the Division of Vector-Borne Diseases at the Centers for Disease Control and Prevention.
Best known for spreading Lyme disease—the most pervasive vector-borne disease in the Northern Hemisphere––ticks efficiently harbor many harmful bacteria, parasites, and viruses that can infect people when they latch on for a blood meal. These tiny, spider-like arthropods transmit agents causing at least 16 diseases in the U.S., and many more worldwide.
And while the Northeast and upper Midwest are hotspots, ticks are on the move. Changing climate facilitates their spread, while expanding suburbs provide ideal habitat for white-footed mice—their main disease reservoir—and deer, a key host. That means ticks are infesting new areas where they can encounter more people, sometimes in “crisis proportions,” says Thomas Mather, who directs the University of Rhode Island’s TickEncounter and Center for Vector-Borne Disease.
Reported cases of Lyme disease show a steady rise during the last 15 years. But a recent study based on commercial insurance claim data suggests actual cases are most likely underreported, with Lyme infecting around 476,000 people a year and medical costs up to $1 billion.
Most tickborne infections are curable if detected early, though not all respond to available treatments. Some diseases, including post-treatment Lyme syndrome, can disable or kill. Complicating matters, some can elude diagnosis. For weeks post-infection, Lyme antibody tests are only about 50-percent effective, making false negatives common. There is no standard panel of tests, and “comprehensive tickborne disease detection is perhaps five years away,” says Laura Goodman, an emerging infectious disease researcher at Cornell University.
Researchers are now scrambling to better understand, test for, treat, and cure tick-borne diseases, as well as find ways to prevent them.
“The general public needs to understand that tickborne diseases in the United States have reached epidemic proportions and are a significant threat to public health,” says Daniel Sonenshine, a tick expert and guest researcher at the National Institute of Allergy and Infectious Diseases.
Ticks’ expanding range
Maria Diuk-Wasser is an epidemiologist and ecology professor at Columbia University who is working on the front lines of tick research. For the past few years, she’s tracked them encroaching into the urban landscapes of New York City, initially on Staten Island, which is now a hotspot for tickborne diseases.
Her current project studies the arthropods’ march westward from Long Island into Queens and Brooklyn. Diuk-Wasserand her team are collecting ticks along a 31-mile transect, mapping their prevalence within parks, cemeteries, and other green spaces and testing them for disease. They’ve also installed 40 camera traps to photograph and count animals that sustain ticks, from deer and white-footed mice to possums, shrews, squirrels, raccoons, and more.
At one sampling site in Christopher Morley Park in Roslyn, Diuk-Wasser unpacks a surprisingly low-tech tool: a three-by-three-foot piece of tan corduroy fabric tethered to a rope. She drags it along the grassy edge of a trail for perhaps 10 yards, then flips it over and kneels to examine it. “Here’s one,” she says, picking up a tick nymph with tweezers and dropping it into a tiny tube of ethanol. She logs the time and GPS location on her phone.
Peering at her quarry, I can see why nymphs are likened to poppy seeds. This young tick is a miniscule black dot, and it terrified me. It’s so tiny I can’t imagine ever finding it if it latched on to feed.
That’s exactly why spring and early summer are the most dangerous times of year, Diuk-Wasser says: When last years’ larvae emerge as nymphs, they start searching for hosts, and they can transmit pathogens to humans. Adults, which are somewhat easier to spot, are most active in fall and early spring, though they are also out and biting in winter on days when temperatures rise above freezing.
Sweeping for ticks in busy Forest Park, Queens, Diuk-Wasser also found adults, some the size of sesame seeds.
Diuk-Wasser’s findings provide an example of how ticks are vastly expanding their range, often into more urbanized areas where people are less on their guard. Ticks are spreading in tandem with their most important hosts, deer, as well as the rodents that serve as disease reservoirs, explains Rick Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies in Millbrook, New York.
Deer were common in New England when European settlers arrived, but as they were hunted and forest habitat was cleared for farmland, populations declined. “There were basically no deer in Connecticut by 1900,” says the CDC’s Beard. However, regional populations had rebounded to perhaps 80,000 by the turn of the 21st century as the landscape reverted to a suburban blend of housing and patchy woods, he says. Human hunters are now their only remaining predators.
Ticks are also expanding their turf due to climate change. With milder winters, ticks are moving north, emerging earlier, and staying out longer, Beard says.
With more people encountering more ticks, infections are rising. In the Northeast, more bites now happen in backyards, working in the garden, or walking the dog in the neighborhood than out hiking. Back in the 1980s, there were only a few Lyme disease cases in Maine, says Robert Smith, a doctor who also studies vector borne diseases at the Maine Health Research Institute. “Now we average 2,000 reported cases a year,” he says.
There’s also been an increase in the known diseases ticks carry. In the 1960s, when Sonenshine first started studying tickborne illnesses in the U.S., only a few infected humans. Now there are at least 16, including a second bacterium that causes Lyme disease; alpha-gal syndrome, a tick bite-triggered red meat allergy that can cause anaphylactic shock; and the rare, potentially deadly flu-like diseases caused by the Heartland and Bourbon viruses.
Experts debate whether these diseases are new or just newly recognized. Goodman thinks some may be novel viruses. Others, including Sam Telford, a tick expert and professor of infectious disease and global health at Tufts University, think these diseases have likely existed for thousands of years, but with new molecular tools, we’re now better at detecting them. Some pathogens have adopted new vectors, such as a strain of Powassan virus that is now carried by deer ticks, which regularly bite humans. It can prove deadly, triggering brain inflammation.
The bottom line is that the risks from tick-borne ailments have increased. “If you're in an area where these diseases are endemic, every year is a bad year for ticks,” says Beard. The challenge now is increasing awareness among people who are not used to worrying about ticks—and getting more medical experts to recognize the symptoms early.
Diagnosing a tick bite
Malachowski’s illness began when she came down with a “summer flu” in 2012 and developed a rash— symptoms that mimic many other ailments. A military doctor diagnosed it as a spider bite, slathered the site in topical cream, and prescribed antibiotics.
The rash spread across her hip, and over the next few months, she hit a frightening mental and physical downward slide. She was exhausted, uncoordinated, confused, and struggling to read and write. But doctors insisted there was nothing wrong: She’d had the treatment, so she needed to move on. “That was a fateful day, because it’s the day I became disabled for the rest of my life,” she says.
Eight months after she first got sick, she piloted her last flight. “I had to ground myself,” she says, “because I started having problems answering radio calls with air traffic control.” Doctors thought she had multiple sclerosis; another told her to see a psychotherapist. But the one that most rankles her is a rheumatologist who said, “You've been a high-performing woman in a male dominated field for a long time. Maybe this is your body's way of telling you it's time to retire.”
Some of the 16 recognized tick-borne diseases are rare, newly discovered, or difficult to diagnose. Like Malachowski, many people present with flu-like symptoms and rashes that are easy to mistake for other illnesses.
Diagnosis gets even trickier in cases like hers, where people are co-infected with multiple pathogens. In rare instances, this creates an emergency.
Harvey Perry, a then 63-year-old banker and conservationist from Rhode Island, contracted three diseases from the same tick bite. His doctor treated him with doxycycline after a classic Lyme bull’s eye rash blossomed on his arm. Then he collapsed: He also had babesiosis, a rare infection of the red blood cells.
Within days he was rushed to the hospital, where his fever spiked to 104°F, his blood pressure plummeted, and his liver and other organs started shutting down as he lay in bed, curled in a fetal position, hallucinating, for days. “They finally figured out I had anaplasmosis, too, which was killing my white blood cells,” Perry says.
Like Malachowski, he partially recovered after getting a cocktail of antibiotics and antiparasitics, but his life was altered forever. After being discharged, Perry was frail, fatigued, unsteady, and “feeling like I was 90 years old.” He also had some brain damage: He’d lost his mental maps and couldn’t remember how to get from one place to another.
The good news, Smith says, “is that except for Powassan virus, we have treatments for these infections, and fortunately, you can use the same antibiotic, doxycycline, for a number of them.”
However, there are caveats. Older people and those with less robust immune systems are at greater risk of serious problems. Some cases mysteriously worsen despite care, and Sonenshine notes that “treatment is significant, but not sufficient. Some cases progress to serious and even fatal outcomes.”
Post-treatment Lyme disease syndrome can include chronic joint pain, heart problems, neuropathy, memory loss, and debilitating fatigue, all of which can last indefinitely. It affects 10 to 20 percent of those who were properly treated, says Smith, as well as the untreated. Meanwhile, the condition remains mired in controversy, largely because researchers haven’t identified consistent biomarkers to confirm it.
There may be some parallels between this syndrome and long COVID, says Beard, particularly regarding inflammation and possible autoimmune issues. The hope is that intensive long COVID research will provide insight into chronicsymptoms attributed to Lyme. It’s become a focus of the Tick-borne Disease Working Group, established by Congress in 2016, which will present a new report at the end of the year.
Preventing tick-borne disease
Though ticks transmit three-quarters of all vector-borne infections, there is far less funding and research focused on ticks than mosquitoes, and efforts to develop vaccines against tick-borne illnesses were abandoned after poor sales of an older, discontinued Lyme vaccine. Pfizer/Valneva announced completed phase-two clinical trials for a candidate vaccine for Lyme disease in April 2022, and Yale researchers are working on another based on mRNA technology. But for now, it’s best to avoid getting bitten in the first place.
Part of the problem is that ticks are especially stealthy parasites. The unusual anatomy of a tick’s mouth parts, along with an amazing array of chemicals in its saliva, can allow it to feed unnoticed for days at a time. Molecules in tick saliva mute pain and itch, while enzymes destroy tissue, etching out a feeding cavity. A gluey cement anchors the tick in the skin, and anticoagulants prevent clotting. Other chemicals silence the host’s immune system.
If you’re bitten, Mather says, your chance of getting sick depends on three factors: the species, the geographic location, and how long the tick was embedded. In the Northeast and Upper Midwest, half of all deer ticks may carry Lyme disease; in the South and West, less than 10 percent have it. A feeding tick typically takes 36 to 48 hours to transmit an infectious dose of Borrelia burgdorferi, the corkscrew-shaped Lyme bacterium. However, with ticks carrying numerous pathogens, there is no safe attachment time. It can take just 15 minutes to get Powassan virus.
To protect children, Cornell University experts are helping schools in New York State control ticks near buildings and on sports fields and playgrounds.
Especially during peak tick months, the CDC recommends using an insect repellent registered by the EPA; wearing closed-toes shoes and long pants treated with the insecticide permethrin; and tucking pants into treated socks. If you’re hiking, stay in the middle of trails, as edges may be infested, and don’t forget protocols during everyday activities. Once back inside, throw clothes in a hot dryer, do a tick check, and take a shower.
“It’s often the tick you don’t see that will make you sick,” says Beard.
If you discover a burrowed tick, grab it close to the skin with tweezers and pull it straight out—don’t twist—and then clean the bite with alcohol or soap and water. You can confirm the species and possible risk for free by uploading a photo of the tick to TickSpotters; experts usually respond within 24 hours. Save the tick in a plastic bag in the freezer: Should symptoms develop, send it for testing. If you have a fever or a rash, call your doctor, says Smith.
“The world is a different place than the one that I grew up in,” say former patient Perry. “We have to live differently.”