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ticks

It’s tick season. Here’s everything you need to know about Lyme disease.

Photo by Ben Garver/The Berkshire Eagle via AP

It’s officially summer. The sun is out, and so are the ticks.

University Distinguished Professor Kim Lewis. Photo by Adam Glanzman/Northeastern University

Tick season is underway in the U.S., a reality that can make even the most avid outdoor adventurers’ skin crawl. For people who spend any time outdoors during the warmer months, the blood-sucking arachnids’ emergence means a risk of more than just itchy bug bites. The creepy-crawlies can carry diseases, like Lyme disease.

Lyme disease isn’t a straightforward ailment, says Kim Lewis, university distinguished professor of biology and director of the Antimicrobial Discovery Center at Northeastern. It can be an acute infection, but can also develop into a longer term condition. Lewis is studying the remaining mysteries of the disease and developing treatments.

If you never go into the wilderness, can you still encounter ticks that carry Lyme disease? 

Yes. Suburbia creates an ideal environment to foster these ticks.

It’s actually about a growing population of mice, Lewis says. In the suburbs, mice don’t have a lot of predators and so their population has ballooned. And, he says, the white-footed mouse is the main carrier of ticks.

Going out into the wilderness is “absolutely a risk factor,” Lewis says. Ticks live in grassy, brushy, or wooded areas. “It’s whatever environment where mice live. Just keep in mind that Lyme comes from a little town in Connecticut, the town of Lyme. The regular people living in the town of Lyme were exposed to their backyards and parks. That’s where they picked it up.”

Do all ticks carry Lyme disease?

No. Commonly known as deer ticks, the tiny blacklegged ticks are the ones that carry Lyme disease. Immature ticks, called nymphs, are about the size of a poppyseed and adults are about the size of a sesame seed. Ticks at both of those life stages can transmit the bacteria that causes the disease.

But not all blacklegged ticks will give you Lyme disease. “It depends on the area,” Lewis says, “but you can have up to half of the ticks carrying bacteria.”

Wait a second. There’s bacteria involved? 

Yes. Lyme disease is caused by the bacterium called Borrelia burgdorferi. When an infected tick bites you, it transmits that bacteria in its saliva.

So if you’re bitten by an infected tick, are you infected immediately?

Probably not. “What happens is that the tick bites you and then it takes some time for the tick to get engorged with blood,” Lewis says. “At some point after that, the Borrelia Burgdorferi is released with tick saliva. It takes hours. It doesn’t happen immediately.”

So you don’t have to check yourself constantly for ticks.

What symptoms should you be watching for?

The classic indication of a Lyme disease infection is a rash that looks like a bull’s eye. Centered around a red spot where an infected tick has bit someone, the circular rash expands as the bacteria disseminates throughout the body, Lewis says. But not everyone infected with Lyme disease gets a bull’s eye rash, or you might not see it.

Other symptoms are a lot like those of the flu: muscle aches, fever or chills, fatigue, headache, and sometimes joint pain. If you think you might have Lyme disease, talk to your doctor. They will likely administer a blood test.

If you are infected, can you be treated?

There is a treatment that is effective in most cases, if you identify an infection early enough. If your doctor thinks you have an active, acute Lyme disease infection, or if a blood test reveals antibodies for the disease, they will likely prescribe an antibiotic.

Most people will get better from that treatment. However, “in those where it’s not diagnosed in time, then it can turn into more unpleasant conditions,” Lewis says. It can get into the nervous system and cause neurological symptoms, or get into the joints and cause arthritic symptoms, for example. Antibiotics can also help treat those more severe cases, too.

But, when left unresolved for six months to a year, Lyme disease symptoms can become “highly problematic,” Lewis says. This can happen when someone has mild symptoms and doesn’t realize they have Lyme disease or in about a tenth of cases even after treatment, he says. This is often called chronic Lyme disease, but the medical community usually calls it post-treatment Lyme disease syndrome (PTLDS).

What are the symptoms of post-treatment Lyme disease syndrome?

Some of the symptoms are more severe versions of the symptoms of acute Lyme disease: headaches, joint pain, muscle aches, and stiffness. But there can also be facial palsy (when one or both sides of the face droops), arthritis and swelling, heart palpitations, dizziness, shooting pain or numbness, and difficulty thinking from brain and spinal cord swelling.

Can you treat PTLDS?

“That’s a conundrum,” Lewis says. “It is frustrating for everybody, including for the doctors, to conclude that they don’t have a treatment.”

In his lab, Lewis is working on two approaches to treating PTLDS. At the root of both is his discovery that the microbiome of patients with PTLDS has changed.

“If that is causal to the disease, or at least an important component of the disease, then there’s a possibility to interfere by restoring a proper microbiome in those people,” he says. So his team is working to develop a treatment to restore the microbiome balance in patients suffering from PTLDS.

But that’s not all. Lewis is also developing a way to treat acute Lyme disease to prevent it from progressing into a long-term condition. The broad-spectrum antibiotics that are used to treat the disease harm the human microbiome, so “if a healthy microbiome is part of our resistance mechanisms, then I think that may very well increase the probability of getting chronic Lyme,” he says. So Lewis’s team has created an experimental compound that can specifically target Lyme disease without killing off the beneficial microbes.

“We have high hopes that this is going to be perhaps the first specific or dedicated treatment for Lyme disease,” he says.

How do you prevent a tick bite in the first place?

Ticks can get onto humans when they brush up against tall grasses, bushes, trees, or leaves. One way to avoid them is to walk in the center of trails when outside.

You can also treat your clothing with a tick-repelling chemical called permethrin. There are several products on the market, and the U.S. Centers for Disease Control and Prevention suggest using something with a 0.5% concentration of permethrin or building pre-treated clothing and gear.

There are also insect repellents that protect against ticks, such as those containing DEET, picaridin, and other compounds. The Environmental Protection Agency has a search tool that helps users identify what product is best for their needs.

Once you go back indoors, a thorough check of your body, clothing, gear, and pets is a key part of catching ticks before they have a chance to latch on and pass on any bacteria. The CDC recommends taking a shower within two hours of going indoors and checking your entire body for the creepy crawlies, particularly in the crevices, folds, and where hair grows on your body.

If you find a tick attached to yourself, carefully remove it with fine-tipped tweezers. You want to grasp the tick as close to your skin as possible, gently pulling with steady, even pressure so that you take the entire tick—including its mouthparts—off your body. You can dispose of the tick by putting it in alcohol, wrapping it in tape, or putting it in some otherwise completely sealed bag or container.

 

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