Ticks on the move: Why are these tiny pests and their illnesses spreading?
June 5, 2019
Ticks are among some of the tiniest warm weather pests; most that bite humans are about the size of a poppyseed. But they’ve been growing in numbers in recent years and expanding their territory across the United States.
In 2017, a record number of cases of tickborne diseases were reported to the Centers for Disease Control and Prevention (CDC) - everything from Lyme disease and Rocky Mountain spotted fever to babesiosis, ehrlichiosis, anaplasmosis, and Southern Tick-Associated Rash Illness.
The effects of climate change and increased globalization have created a perfect storm for the rise of vector-borne illnesses, or infections transmitted to humans by a living animal. A rain-soaked spring, followed by a longer summer, extends the feeding season for mosquitoes, fleas and especially immature ticks, who then transmit a growing list of pathogens.
May through September is prime time for ticks. So as you prepare for summer travel and more time spent outdoors, it’s worth exploring why the tick population is booming and what you can do to protect yourself against these tiny but potentially harmful pests.
3 reasons ticks are migrating to more places
A lot of infectious diseases are transmitted through animals or insects — West Nile and Zika are examples of mosquito-borne viruses that have made headlines in Texas and beyond the last few years.
Ticks can’t fly or jump, but they tend to live in heavily wooded areas, on leaves or grass. When a host animal (usually a mouse, squirrel, or deer) brushes up against that area, the tick climbs aboard, burrows into its fur and has a meal, which in this case is blood.
If that host animal is carrying bacteria, the tick takes on that pathogen.
The risk of getting a tick-borne illness is related to how long the tick is able to feed on you. They usually need 36 to 48 hours to deliver the bacterium into your system, according to the CDC.
So that’s the good news: Find the tick and remove it within 24 hours and you shouldn’t get infected. The bad news: It’s not always easy to find the tick. Immature ticks called “nymphs” typically transmit bacteria to humans, and they can be difficult to detect.
The risk of getting a tick-borne illness is related to how long the tick is able to feed on you. They usually need 36 to 48 hours to deliver the bacterium into your system.
For decades, ticks and their diseases had been mostly confined to specific geographic regions.
For example, the black-legged ticks responsible for spreading bacteria such as Borrelia burgdorferi or Anaplasma phagocytophilum have largely been found in Northeast and Midwest states. (The disease was first identified in Old Lyme, Connecticut, in 1975.)
But in recent years, ticks have been expanding to new geographies for several reasons:
- Climate change creates new, favorable environments for ticks: There’s no doubt ticks are migrating because, thanks to global warming, they can now survive in places that years ago they couldn’t because it was too cold. And if a tick can carry a pathogen, that sets up the human population to be exposed. Slightly longer summers also play a role in this growth, creating a prolonged feeding season for ticks.
- Humans and animals travel more now: We can get just about anywhere in the world in less than a day - and that globalization plays a role in spreading infectious diseases. It’s not just humans traveling, either. If a tick were to board a plane in the Northeast and go somewhere new, the bacteria and any associated illness can travel with it.
- We’re living closer to ticks and the animals that carry them: As development has encroached on wooded areas, people are living in closer proximity to much of the wildlife that ticks like to feast on. The black-legged tick is often referred to as a “deer tick,” but Bambi is not necessarily to blame for most of the spread of Lyme. The white-footed mouse is a primary culprit, with the majority of ticks getting their first blood meal on the backs of these unkempt rodents.
A trio of pervasive ticks and their illnesses
Only a fraction of the tick species in the United States bite and transmit diseases to people. But the number has grown recently, and some ticks can be very aggressive. Here are a few of the most common ticks and their associated illnesses:
The lone star tick gets its name from the Texas-shaped white spot on the adult female’s back, but it is found primarily in southeastern states. Eager to feed on humans, it can spread Southern Tick-Associated Rash Illness (STARI), Heartland Virus, ehrlichiosis, and tularemia.
The American dog tick, also known as the wood tick, is most closely associated with Rocky Mountain spotted fever (RMSF), but it can also transmit tularemia. The adult female likes to feed on dogs, but it is typically the nymphs that transmit RMSF to humans. Originally identified in the Rocky Mountain region, most reported cases have come from five states: North Carolina, Tennessee, Missouri, Arkansas, and Oklahoma, according to the CDC.
The black-legged tick, aka the deer tick, is linked primarily to Lyme disease, the most commonly reported tick-borne illness with about 30,000 cases per year, according to the CDC. The agency estimates that the number of unreported cases of Lyme would bring that total closer to 300,000. The majority of Lyme disease cases are concentrated in the Northeast and Midwest, with some growth on the West Coast. The black-legged tick is also to blame for anaplasmosis, babesiosis, and Powassan disease.
How to protect yourself from ticks
Ticks are more ubiquitous than ever, but the strategy of how to deal with them remains the same:
- Check your body for ticks. Your risk increases the longer the tick is on you. If you’re in an environment where there’s potential for a tick-born disease - high grass, heavy woods - it doesn’t matter whether you’re in Texas or Connecticut, check your body for ticks and have somebody help you. Or use a hand-held mirror to check the places you can’t see. Unfortunately, ticks can be found almost anywhere on the body, including places that you might not normally look, such as the back of your knees, under your arms, between your legs, and yes, even your belly button! No body site is off limits for these critters. Parents should conduct thorough tick checks on children. If a tick is removed within 24 hours, it’s unlikely to infect you with its pathogen.
- Wear clothing that covers areas of your skin most likely to brush against a tick. The CDC also recommends using clothing and products pretreated with the insecticide permethrin, such as boots, pants, socks, long-sleeved shirts, and tents.
- Use EPA-registered insect repellants: Many of those contain DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone.
- Bathe or shower right after coming indoors: It will make it easier to find and remove ticks.
- Put clothes in the dryer on high heat: Tumble dry for 10 minutes to kill any ticks clinging to your clothes.
- If you do find a tick, remove it carefully: Use tweezers to grab the tick as close to the skin as possible, and pull upward steadily and slowly. Try not to break off any of its mouth-parts in the skin. If you do, pull those out with tweezers. Then clean the bite area and wash your hands. Do not crush the tick. Flush it down the toilet.
A tick tale from my life
Unfortunately, no one is spared from ticks. Last summer, my son went to boy scout camp in Arkansas, and after a long hike (he insisted on being in the front for this particular hike) came back with 20 ticks all over his body. He went to the counselor and said, “I think they could be ticks,” (he has been well trained, after all) and, lo and behold, they were.
we knew the ticks weren’t there before the hike, and he found them right after
the hike. So we removed them in proper fashion, watched him closely, and he was
fine. No antibiotics necessary.
Which points out another important point: Rule No. 1 in preventing tick-related infections is don’t panic. Ticks need time to pass the bacterium to humans. Remove them quickly and properly, and you should be fine.
If you or a loved one experience symptoms of a tick-borne illness -- usually acute onset of fatigue, fever, nausea and frequently associated with various rashes - antibiotics can be an effective treatment. In severe cases and depending on the pathogen, involvement of the joints, heart, brain and blood cells can occur.