Global Warming, Ticks, and Lyme Disease

Global Warming, Ticks, and Lyme Disease. Is climate change causing an infestation of ticks? Yes, scientists say. So if you’re thinking of hunting, trekking, hiking, camping or going on some other outdoor activity this summer, take extra precautions. The United States Centers for Disease Control warns that the tick population is expected to pose a far greater threat of Lyme disease transmission this spring.

Researchers at the Cary Institute of Ecosystem Studies in Millbrook, New York also warn that people heading into the woods this spring in the Northeastern states will be at higher risk than usual of coming down with Lyme disease as insect populations are expected to swell after the warm, mild winter.

Over the past 30 years, cases of Lyme disease have spiraled from a few hundred to 30,000 reported each year — with 90 percent of them occurring in the Northeast — Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont, New Jersey, New York and Pennsylvania.

A bacterial infection from a bite of an infected tick, Lyme disease symptoms typically show up within three to 30 days of the bite. The first sign is usually a circular rash that looks like a bull’s eye.

As the infection spreads, you may have fever and flu-like symptoms. And while treatments are generally effective, if the disease isn’t treated early with antibiotics, it can lead to long-term, recurrent arthritis, cause chronic fatigue and term neurological problems.

After days of unusually high temperatures in March, U.S. health officials are warning residents of Maryland and Virginia — further south from the Northeastern states — to also be vigilant for ticks and to protect themselves from the threat of Lyme disease, the Associated Press reports.

People who are venturing into areas with thick undergrowth should wear light-colored clothing to make the bugs easier to spot, advises public health entomologist Eric Dotseth. He also suggests that people examine themselves and their pets thoroughly because the black-legged tick that carries Lyme disease –previously known as the deer tick — is tiny and hard to find.

Ticks can attach to any part of the human body — including hard-to-see areas such as the groin, armpits and scalp. “They are cueing in on things like heat, carbon dioxide, motion, sweat — all of these things that suggest a living, breathing, vertebrate host,” he tells AP.

“You’ll even see them sometimes on the vegetation. They’ll be wiggling their legs around like little antennae searching. Then what they do when they find that vertebrate host, they will latch on.” Typically, ticks must be attached for 36-48 hours or more before the disease can be transmitted.

Doctors say they should be removed carefully, with tweezers and by the head. “Do not, under any circumstances, burn the tick while it’s touching you, or put Vaseline or another chemical on the tick to get it to drop off,” says Dr. Erika Pallie of Morgantown. The infection can only be spread by ticks, and a person with Lyme disease is not contagious.

Lyme disease ticks spreading south and into Canada
And it isn’t only the intensity of tick transmission that’s being influenced by warming temperatures from climate change — but also where ticks choose to live, claims Nick Ogden, a zoonoses expert with the Public Health Agency of Canada. As regions of the southern U.S. experience overly hot temperatures and become inhospitable to ticks, other parts of North America — including Canada — may become newly suitable.

Dr. Richard S. Ostfeld, a disease ecologist who has studied the ticks and their habitats for 20 years, also cautions that warming from climate change is helping expand the ticks’ habitat.

“Climate warming is probably allowing ticks to spread northward into northern New England and Canada but (it) can’t explain their expansion southward into Maryland and Virginia,” he says. “And little evidence links recent warming trends in the Northeast to the proliferation of ticks there, although warming could play a role.”

Over the past 60 years, average annual temperatures in Canada have increased by 1.4 degrees Celsius (2.5 degrees Fahrenheit), and a study published in March by Canadaian zoonoses expert Ogden and his colleagues suggests that the area of eastern Canada habitable by ticks is expanding. From about 18 percent of the population affected in 2010, more than 80 percent are expected to be affected by 2020.

“We’ve had a prediction of increasing risk, but now we’re seeing it,” says Ogden.

Another factor is the fluctuating numbers of acorns and mice, explains Dr. Richard S. Ostfeld, who has studied the acorn-mice-tick connection for years and whose work is funded by the National Science Foundation.

White-footed mice — the preferred host of black-legged ticks — experienced peak populations in 2011, resulting from a bountiful acorn crop in 2010, Dr. Ostfeld explains to the New York Times.

Because there were so many mice to feed on when the ticks were larvae last year, the percentage of Lyme-infected nymphs will be especially high this spring, he predicts. “About 90 percent of larvae that feed on mice get infected. That’s twice as much as with any other host.”

Ticks prefer mice because they are poor groomers, but the ticks also latch on to various mammals. Whitetail deer have been traditionally regarded as the main vector, but Dr. Ostfeld argues that the deer-Lyme connection has been “way overemphasized.” Ticks feed as larvae, nymphs and adults — and infected nymphs are responsible for the vast majority of Lyme cases.

Dr. Ostfield believes this year, the population of ticks will be the highest so far, breaking the record set five years ago after a similar boom-bust cycle of acorns and mice. He’s convinced of this, after seeing this year’s abundance at the research sites he monitors and knowing that a single tick can deposit 3,000 eggs.

For people, the May-to-July nymph season will be especially dangerous where Lyme disease is concerned, because it’s a time of year when many people head to the woods and ticks often go unnoticed.

Following the boom cycle, last year’s acorn crops were the smallest ever seen — causing mouse populations to dive. “That means plenty of Lyme-infected ticks will be looking for a blood meal,” he says. “Instead of finding mice in the woods, they’re going to find mammals like us.”

“They’re really tiny — about as big as poppy seeds—so they’re hard to detect,” he says. “You might not even know they’re crawling on you or embedding in your skin.

Indeed, David Figura of The Post-Standard recounts how Peter Palumb, U.S. Army recruiting battalion officer in Syracuse, recently walked on land adjacent to Green Lakes State Park in Syracuse, Central New York and afterward, picked a whopping 17 ticks off himself.

Green Lakes State Park counts among the hot spots for ticks this spring — and many areas of Central New York are becoming “local Ground Zeros” for Lyme disease, Figura writes.

How do you know you have Lyme disease?
If you missed the tick bite — and you can because the tick is tiny and its bite is usually painless — you will know you may have Lyme disease if there’s a circular rash that look like a bull’s eye surrounding the tick bite. As the infection spreads, you may have:

Flu-like symptoms. Fever, chills, fatigue, body aches and a headache may accompany the rash.

Migratory joint pain. When the infection is left treated, you will develop bouts of severe joint pain and swelling several weeks to months after infection. The pain can shift from one joint to another, but your knees are most likely to be affected.

Neurological problems. These include numbness or weakness in your limbs, inflammation of the membranes surrounding your brain — meningitis, impaired muscle movement and temporary paralysis of one side of your face –Bell’s palsy. These may occur weeks, months or even years after an untreated infection.

Less common signs and symptoms. Some people even experience an irregular heartbeat or heart problems several weeks after infection, but this rarely lasts more than a few days or weeks. Hepatitis, severe fatigue and eye inflammation are possible as well.

In its late stages, Lyme disease triggers symptoms similar to those of fibromyalgia or chronic fatigue syndrome. This is known as chronic Lyme disease — and more research into this form of Lyme disease is needed.

Contact your doctor immediately
If you know you’ve been bitten and experience signs and symptoms of Lyme disease and if you live in an area where Lyme disease is prevalent, contact your doctor immediately.

The longer the tick remains attached to your skin, the greater your risk of getting the disease. Lyme disease can be treated effectively with antibiotics — but the sooner treatment begins, the quicker and more complete the recovery.

After treatment, some people still suffer from muscle or joint aches and nervous system symptoms. This is called post-Lyme disease syndrome (PLDS) and long-term antibiotics haven’t been shown to help with PLDS. But there are ways to help with the symptoms of PLDS, and most patients do get better with time.

How to prevent ticks
Prevention, however is best. The CDC suggests:
• Wear light-colored clothing with a tight weave to spot ticks easily.
• Wear enclosed shoes, long pants, a long-sleeved shirt and a hat.
• Tuck pant legs into socks or boots and shirt into pants.
• Place tape where pants and socks meet.
• Check clothes and any exposed skin frequently for ticks while outdoors.
• Walk in the center of trails and avoid overhanging brush.
• Consider using insect repellent. Use insect repellent containing 10 percent to 30 percent diethylmetatoluamide (deet) on your clothing and exposed skin — but not your face.
• Bath or shower as soon as possible after going indoors (preferably within two hours) to wash off and more easily find ticks that may be on you.

To remove a tick from skin, use tweezers to grab it close to the mouth, as close to the skin as possible, and gently and steadily pull it straight off without twisting. If you think it might be a deer tick, it’s a good idea to save it in some kind of container and show your doctor.

Rising risks also mean that “parents and pediatricians need to be vigilant,” says climate change expert with the CDC, Ben Beard.

The CDC’s website shares more suggestions, including how to create tick-free zones. One of these suggestions includes putting playground equipment in the middle of the yard — rather than on a forest fringe where ticks thrive, Lynne Peeples writes in a blog on Huffington Post.

Other diseases as well
Lyme is just one of a lengthening list of emerging infectious diseases that experts claim are being spread and made more intense by increasing temperatures and altered precipitation patterns that accompany climate change. Other diseases being spread are West Nile virus and Chagas disease, as well as Dengue fever.

Cases of West Nile virus reported to the CDC rose from 21 in 2000 to more than 1,000 in 2010, for example.

“There are lots of factors that contribute to emerging infectious diseases,” says CDC’s Beard tells the Post writer. He ticks of the following factors: the influence of international travel, wildlife management, the suburban lifestyle. “But climate disruption and change clearly have an impact,” he says.

Way back in 2005, John Brownstein, a pediatrician and researcher at Children’s Hospital Boston predicted the tick-borne diseases infiltration and spread in Canada that we are seeing today.
He and his team use climate change forecasts to project where a range of infectious diseases, including dengue and Lyme disease might appear next. They’re using what he calls “digital disease detection” — and the public can help by self-reporting diseases online or via a mobile application, Peeples reports.

In 2011, WireService.ca reported that starting from September to December 2011 ticks are being seen in numbers never seen before in Canada, in one specific area of Mississauga, south of the QEW — the 400-Series highway in the Canadian province of Ontario linking Buffalo, New York and the Niagara Peninsula with Toronto.

This week, the BBC also reports a rise in ticks in recent years, and a webpage on the National Health Service is devoted to tips on how to prevent and treat Lyme disease.

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