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Entomological Society of America
Entomological Society of America

Lyme Disease-Spreading Ticks Now in Almost Half of U.S. Counties

Entomological Society of America
Entomological Society of America

Doctors depend on scientific research to inform the diagnoses they make and the treatments they recommend. When that information is out of date, the doctors and their patients are at a real disadvantage. That’s certainly the case with Lyme disease research. A new report released this morning shows that Lyme disease-spreading ticks can now be found in nearly half of all U.S. counties—a 50 percent increase since the last prevalence study in 1998.

Rebecca Eisen is a biologist at the U.S. Centers for Disease Control and Prevention (CDC). When she realized that the last national survey of tick distribution had been completed nearly 20 years ago, she decided it was time for an update. To ensure that they could compare their results to those from 1998, Eisen and her colleagues used the same techniques employed in the earlier study. They tabulated reported sightings of the blacklegged tick (Ixodes scapularis) and the less-common western blacklegged tick (Ixodes pacificus), both commonly known as deer ticks.

Blacklegged tick. Image credit: Gary Alpert, Harvard University, Bugwood.org.

The results were alarming. The range of I. scapularis has expanded into 45 percent of U.S. counties. That’s a 50 percent increase from 1998, when the tick could only be found in 30 percent of counties. The tick’s territory increased most dramatically in northern states and remained fairly stable in the South. Eisen and her colleagues also tracked the range of the less-common I. pacificus, which seems to have remained relatively steady. In 1998, western blacklegged ticks were reported in 3.4 percent of counties; by 2015, that number had only risen to 3.6 percent.

The map on top is from 1998, and the one below it is from 2015. Red indicates a county where I. scapular is is established, and blue indicates that it has been reported. Green indicates a county where I. pacificus is established, and yellow indicates that is has been reported. Image credit: Entomological Society of America.

While the majority of patients with Lyme disease can make a complete recovery if they’re treated soon after infection, the research is still vital. As it is now, diagnosing the disease can be lengthy and complicated. A bullseye rash is a pretty good sign that a person has been infected, but many people never develop a rash. The most common symptoms of Lyme—fever, headache, and fatigue—are easily mistaken for symptoms of the flu or a viral infection, and blood tests for Lyme disease are notoriously imprecise.

This research could help doctors spot the disease faster, by knowing if their patients have been exposed to Lyme disease-spreading ticks.

“This study shows that the distribution of Lyme disease vectors has changed substantially over the last nearly two decades and highlights areas where risk for human exposure to ticks has changed during that time,” Eisen said in a press release.

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8 Ways Spiders Are Creepily Clever
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You may already know that spiders can spin intricate webs and poison their prey. But that doesn't even begin to cover the all the sneaky abilities spiders have adapted to become the most fearsome organisms on eight legs. Here are some of the tricks spiders use to catch their meals while avoiding becoming dinner themselves.

1. THEY HAVE SUPER-POWERED SENSES.

Spidey-senses weren't just invented for comic books. Jumping spiders in real life have sharp eyesight and excellent hearing to make up for their inability to spin webs. Scientists long assumed that spiders couldn't hear because they don't have ears. But as researchers reported in a 2016 study, jumping spiders can "hear" perfectly fine—they just use the super sensitive hairs on their legs to do so. These same spiders can also see surprisingly well, as astronomer Jamie Lomax demonstrated when she used laser pointers to lure them away from her desk like they were tiny cats.

2. THEY MIMIC ANTS.

The fact that the jumping spider species Myrmarachne formicaria tricks predators into thinking it's an ant by mimicking its appearance isn't a new discovery. But exactly how it achieves this was unclear until recently. According to a Harvard study published in the Proceedings of the Royal Society B, the spider pulls off this deceptive stunt while using all eight legs to walk. During its performance, it takes 100-millisecond pauses to lift its front two limbs to its head so they resemble antennae. The switch is so fast that to a human looking from above, the spider appears to simply be walking with its back six legs while lifting its front legs off the ground. Scientists had to use high-speed cameras to prove this wasn't the case. 

3. THEY TUNE THEIR WEBS.

Despite lacking ears, spiders have some impressive musical talents. They treat the strands of their webs like the strings of a guitar, tuning them just right so they can detect certain vibrations. For their study published in the Journal of the Royal Society Interface, researchers from the University of Oxford and Charles III University of Madrid observed garden cross spiders maintaining their webs. They learned that adjusting the tension and stiffness of the silk allows the spiders to sense frequencies they can recognize. One signal might mean that prey is near, while another could be connected to structural issues with the web.

4. THEY PRETEND TO BE BIRD POOP.

Spider disguised as bird poop.

Min-Hui Liu et. al, Scientific Reports // CC BY-NC-ND 3.0

Camouflage is not unique among arachnids, but orb weaver spiders may win the prize for the most memorable disguise. In its juvenile stage of life, the spider will surround itself with a thick, white material in the center of its web. Its whitish abdomen blends into the "decoration," making the spider appear as if it's buried in a splatter of bird droppings. The unappetizing look is usually enough to convince predators to look elsewhere for a meal that's easier to stomach.

5. THEY CAST NETS.

Spider with web between it's legs.

Chen-Pan Liao, Wikimedia Commons // CC BY-SA 3.0

Bigger isn't always better when it comes to webs. Take the net-casting spider: The silken trap it uses to snare food is small enough to fit between its limbs. The spider poops out a pale "target" onto the forest floor and then hangs above it waiting, sometimes for hours, for an insect to come along and trigger a "trip wire" connected to the ground. Once that moment comes, it wastes no time lunging at its prey and enveloping it in its web. It then bites and paralyzes its prey before commencing the feast.

6. THEY CAN FIRE THEIR HAIRS LIKE TINY BARBED SPEARS.

If all else fails, at least tarantulas have their spear-like hairs to fall back on. A tarantula deploys its "urticating hairs" when it feels threatened. By grinding its back legs against its abdomen, it's able to shoot the barbed hairs at its target like a shower of tiny throwing stars. You don't have to be a predator to trigger this defense mechanism, as many tarantula pet owners have found out the hard way.

7. THEY SOMERSAULT.

When most spiders need to escape a dangerous situation, they rely on their eight limbs to scurry them to safety. The golden wheel spider curls up its body and rolls down hills to make an even speedier getaway. This type of spider is native to the Namib Desert in southern Africa, where steep, sandy dunes are abundant. When it's tucked into a ball, the spider can reach tumbling speeds of 3.2 feet per second.

8. THEY CREATE BUBBLE SUBMARINES AND SCUBA SUITS.

Even without gills, spiders have adapted some pretty clever ways of surviving underwater for long amounts of time. The diving bell spider weaves web balloons that extract dissolved oxygen from the water around it while filtering out carbon dioxide. Using this improvised scuba suit, the spider can last a whole day before it needs to come up for air. Then there are wolf spiders, which use a much more dramatic survival tactic. A 2009 study found that marsh-dwelling varieties of wolf spiders appear to drown after being submerged for extended periods. But once they're placed on dry land, they twitch back to life. Slipping into a coma underwater is how they're able to evade death.

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We May Be Hardwired to Fear Snakes and Spiders
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Just the mere sight of a daddy longlegs or garter snake can prompt shrieking and shoe-throwing, even though not everyone has had bad experiences with creepy-crawlers. Are we naturally predisposed to hate tiny critters that scurry and slither? A new study suggests so, according to a video from National Geographic (below).

The video highlights a new study by a team of researchers from the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany, and Uppsala University in Sweden, who measured the pupils of 6-month-old babies as they stared at pictures of flowers and fish, or snakes and spiders. Human pupils naturally enlarge as a response to danger—and sure enough, the babies' eyes dilated more frequently when they were exposed to the garden pests. This suggests that our widespread dislike of spiders and snakes might be ingrained in us (although the time your bunkmate hid a spider in your sleeping bag at camp probably didn't help, either).

You can check out the full study online in the open-access journal Frontiers in Psychology. And to help squelch your fears, here are some common (yet wildly inaccurate) myths about spiders, and some dispelled misconceptions about snakes.

[h/t National Geographic]

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