Ticks can’t fly. They don’t jump, or fall on you from above. They wait.
Staked out on the very tips of leaves and blades of grass, they sit, raised on their back legs, reaching out with their hooked front limbs in a pose that’s called “questing,” and they smell you coming. Not your perfume or your stinky sneakers, the scent that ticks detect is your breath—the CO2 that you exhale—and they lean in. “It just takes the slightest brush and they latch on,” said Dr. Richard Marconi, an epidemiologist at Virginia Commonwealth University, “and they don’t waste a lot of time looking for a place to feed. They start eating.”
Ticks are arachnids, tiny vampire spiders that survive by feeding on the blood of other creatures. Light-footed and noiseless, they creep over human skin, usually discovered by accident or careful search. Most people don’t even feel the bite. Ticks are ancient, dating from the Cretaceous period, but the diseases they transmit to humans have been newly accelerating in recent years as both ticks and humans expand their habitats into the same zones.
Take, for instance, Lyme disease, a bacterial infection from the bite of a deer (or “blacklegged”) tick, named for the town in Connecticut where it was first identified in 1975. “Lyme disease wasn’t in the state of Virginia at all in the 1980s,” said Dr. Mark Lepsch, a physician in U.Va.’s Northridge Internal Medicine group. “Even in the 90s, Lyme cases diagnosed here were likely spread from somewhere farther up on the eastern seaboard. Ten years later, Lyme was the leading tick-borne illness in the state.” Today, Virginia is one of 14 key states that account for more than 96% of reported Lyme cases.
Tick-borne diseases are caused by bacteria that live inside of ticks, but ticks play a role in its transmission in a circular, symbiotic way. “One important thing to know is that these diseases cannot be transmitted from one animal to another,” said Marconi. “So, you can’t get, say, Lyme from your dog or from another person. The second important thing is that when ticks hatch from eggs they are called larvae, and at that point they are not carrying the disease—there’s no transmission from the [mother] female tick to the larvae. The only way a tick becomes infected is if it feeds on an infected animal.”
The tick larva takes a bite (called a “blood meal”) from a small, already-infected creature—a mouse, chipmunk, or even some types of ground-feeding birds—and becomes infected itself. Like a foul little courier, the tick then moves through other stages of development (nymph, adult) and passes the bacteria on to animals or people during its next blood meal.
“For Lyme disease to exist in, say, Albemarle county, you have to have a sufficient population of small mammals that serve as ‘reservoirs’ for Lyme disease,” said Marconi. Mice are the most common reservoirs, but deer are also important because they provide convenient transportation. “Deer are basically a vehicle for ticks to travel, and a single deer can cover a lot of ground each day while carrying hundreds or thousands of ticks with it,” he said. “You will not find a deer, particularly here in Virginia or in the Northeast as a whole, that is not relatively loaded with ticks.”
“Changing environmental conditions and land use patterns are very, very favorable for the tick population,” said Marconi. “Warmer winters mean that a lot of the smaller mammals can survive better and serve as reservoirs for ticks, and housing development out in rural areas means that at the edge of all of those nicely cut lawns is low brush and taller grass, which ticks love.”
The most common tick-borne illnesses in Virginia are Lyme disease, Rocky Mountain Spotted Fever, and ehrlichiosis, as described in the nearby table. Symptoms can range from mild to life-threatening. “Ehrlichiosis might be a mild case where you feel tired for a month, or you can die from it,” said Lepsch. Rocky Mountain spotted fever can come on quickly and land a person in the hospital with severe flu-like symptoms. As for treatment, timing is everything.
“If you treat these diseases right up front, patients get better,” said Lepsch, “but if people come in a month after exposure, then the body has used its own antibodies to fight off the bacteria.” The antibodies that target Lyme can later become toxic to a person’s own body and, though chronic Lyme disease is not well-understood, can result in persistent pain and neurocognitive problems. “One big myth is that the disease is curable with antibiotics months or years later,” said Lepsch. “The problem with Lyme is that if you miss it up front and people develop the sequelae [antibodies], there’s not a darn thing we can do.”
An underreported threat
The Centers for Disease Control has concluded that the number of reported Lyme disease cases—about 30,000 per year—likely vastly understates the problem. Labs, not physicians, do the reporting of diagnoses to the CDC, which is triggered by the ordering of a lab test that comes up positive. The problem is, few doctors order the test.
“In 2014 the CDC studied insurance records to figure out how often Lyme was being diagnosed by doctors but not reported,” said Marconi. “They found that compliance with reporting is at best around 5%, so the actual number of cases could range from 340,000 to 600,000 per year.” These larger estimates include situations where a doctor treats a patient with antibiotics for a suspected, but not tested, Lyme disease case, but there are also an unknown number of people who have Lyme symptoms they attribute to something else, and never visit a doctor at all.
If a test for Lyme disease exists, why don’t doctors order it? The answer, says Lepsch, is expediency. “If you’re bitten by a tick and infected with its bacteria, you’re usually not going to get sick with symptoms for five to fourteen days afterward,” he said. “But everybody’s getting tick bites and they’re worried. So if a patient has a high risk story, like a tick that was attached for more than 24 hours, or a ‘bulls-eye’ rash, we go ahead and give them an antibiotic like Doxycycline to treat the infection.”
So, while Lepsch might only see a few actual cases each year where the infection has progressed to full-blown Lyme disease per season, he prescribes dozens of small antibiotic doses as preventative care, none of which go into the CDC’s numbers.
Allergic to meat
Researchers are puzzling through another tick-related illness that causes some people who are bitten by a Lone Star tick to develop an allergy to a specific carbohydrate in meat. People with this “alpha-gal” allergy can experience hives, stomach pain, and difficulty breathing three to six hours after eating any kind of mammalian meat, and the reaction can be life-threatening. Dr. Lepsch’s father was one of the first tick-related meat allergy cases to be diagnosed at U.Va. hospital in the mid-2000s.
“My dad had intermittent periods where he’d swell up like crazy but no allergists could figure it out, until finally [U.Va. researchers] Tom Platts-Mills and Scott Commins made the connection,” said Lepsch. “The allergy does seem to be malleable, in that if you get away from eating meat it can wane, and you can get better.”
Ivy resident Amy Sikes was halfway through a steak burrito bowl when her doctor called to tell her she’d tested positive for the meat allergy. “There is a range of sensitivity and I was on the low end, but a few months later I pulled two ticks off of me and my levels had gone up,” said Sikes, who now steers entirely clear of red meat. “I would love to have a bacon cheeseburger, but not enough to risk a visit to the ER.” Besides her diet, Sikes’ biggest change has been that now she and her family wear 40% DEET bug spray when outside.
Like many people who suffer from the alpha-gal allergy, Sikes must also be wary of medications that are encased in gelatin capsules, because much of that gelatin is derived from beef and pork byproducts. “During a recent surgery, the residents had to find alternative blood thinners and other medicines for me,” she said, “and my pharmacist keeps a list of what I can take, including all of the generic products.” Sikes said she’ll wait a few years and if her sensitivity levels decrease, she’ll try small amounts of meat again. “I’m incredibly looking forward to that,” she said.
A potential vaccine
The Centers for Disease Control (CDC) has recently sounded the alarm on tick-borne diseases, noting that the number of reported cases of Lyme disease in the U.S. has tripled since the late 1990s and cases of all tick-borne diseases increased by 22% from 2016 to 2017. The CDC says that both the range and variety of ticks in the U.S. is increasing due to factors such as changing land use patterns, including the reforestation of northeastern states, as well as climate change patterns that may provide more hospitable environments for ticks.
Surges in tick-borne diseases have led to increased funding for researchers like Dr. Marconi at VCU. Marconi started working on Lyme disease in the late 1980s and came to VCU in 1994, where he created a successful and widely used vaccine to treat Lyme in dogs, called Vanguard. His lab recently received a $2.5 million grant from the National Institutes of Health to develop a vaccine for humans, reflecting the increasing prioritization of research into tick-borne diseases.
“Some minor adjustments at the science level were needed to bring the vaccine up to human standards,” said Marconi, “and now we’ve reached the testing phase. The lengthy part is to advance the vaccine through clinical trials, which are very expensive and take a long time, and to deal with the regulatory issues. I’d say the best-case scenario would place availability at five years out.” Fortunately, there are other avenues for researchers to gather data on diseases like Lyme.
“People often don’t have a good feel for how prevalent tick-borne diseases are in their area because we don’t screen humans for things like Lyme disease,” said Marconi. “But we do screen our pets.” A 2018 study in Great Britain showed that 10 percent of dogs tested positive for Lyme. “When you think about any infection that affects 10 percent of the population, that’s remarkable.”
While Marconi emphasizes that if humans are treated, they will likely come through a tick infection just fine, he notes that animals who have an undetected infection may end up with a chronic case of Lyme disease, for which there is no cure. “If you think of this from the perspective of the disease itself, it has evolved so that these infections generally do not kill their hosts,” he said. “They cause damage over time, but they try not to do it too quickly. They want to live in that host mammal for as long as they possibly can.”
You know what to do
See the nearby graphic for the Virginia Department of Health’s guidance on how to protect yourself against tick bites. If you are bitten, pull the tick straight out of your skin with tweezers, clean the affected area with soap and water, and either flush the tick down the toilet or keep it in a sealed plastic bag to show your physician in the event you become sick within the next 30 days.
Common diseases caused by tick bites in Virginia if left untreated
The Virginia Department of Health says that common tickborne illnesses in Virginia include Lyme disease, Rocky Mountain spotted fever, and ehrlichiosis. Symptoms for each of these illnesses can range from mild to potentially life-threatening.
Lyme disease is caused by the bite of an infected blacklegged (deer) tick. Symptoms develop three days to a month after exposure, and include a “bull’s-eye” skin rash that spreads, fever, headache and fatigue. If untreated, it can cause arthritis, facial paralysis and memory problems.
Spotted fever rickettsia (including Rocky Mountain spotted fever) is caused by the bite of an infected American dog tick. Symptoms appear two days to two weeks after exposure, including fever, rash, headache, nausea, vomiting, abdominal and muscle pain and lack of appetite.
Ehrlichiosis is caused by the bite of an infected Lone Star tick. Symptoms develop one to two weeks after exposure, and include fever, chills, severe headache, muscle aches, nausea, vomiting, diarrhea and confusion. If untreated, it can cause nervous system damage, respiratory failure and uncontrolled bleeding.
Protect Yourself from Tick Bites
To protect against tick bites and the diseases they may cause, the Virginia Department of Health (VDH) and the Centers for Disease Control and Prevention (CDC) recommend that you:
- Avoid areas with high grass and leaf litter, and walk in the center of trails when hiking.
- Use EPA-registered insect repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone. Always follow product instructions.
- Use products thatcontain permethrin to treat clothing and gear, such as boots, pants, socks and camping tents. Do not apply permethrin directly to a person to prevent tick bites.
- Treat dogs for ticks. Dogs are very susceptible to tick bites and to some tickborne diseases.
- Conduct a full-body tick check using a hand-held or full-length mirror to view all parts of your body upon returning from tick- infested areas. Remove any ticks right away.
- Bathe or shower as soon as possible after being outdoors to wash off and more easily find crawling ticks before they bite you.
- Wash and keep clothes in a dryer on high heat for 10 minutes after fully dry to kill ticks.