Nature Bites Back / The “Tick” Thing – Diseases

Two articles about tick-born disease dangers: one social media; one from Washington University in St Louis.  Do “ASD” Asperger people run away from environmental threats (chemicals, noise, light, crowding, disease – “sick buildings”; pathogens, parasites, etc) due to a natural “ecological fear response”?

Oh, Lovely: The Tick That Gives People Meat Allergies Is Spreading

06/20/2017

By Megan Molteni for WIRED.

First comes the unscratchable itching, and the angry blossoming of hives. Then stomach cramping, and — for the unluckiest few — difficulty breathing, passing out, and even death. In the last decade and a half, thousands of previously protein-loving Americans have developed a dangerous allergy to meat. And they all have one thing in common: the lone star tick.

Red meat, you might be surprised to know, isn’t totally sugar-free. It contains a few protein-linked saccharides, including one called galactose-alpha-1,3-galactose, or alpha-gal, for short. More and more people are learning this the hard way, when they suddenly develop a life-threatening allergy to that pesky sugar molecule after a tick bite.

Yep, one bite from the lone star tick — which gets its name from the Texas-shaped splash of white on its back — is enough to reprogram your immune system to forever reject even the smallest nibble of perfectly crisped bacon. For years, physicians and researchers only reported the allergy in places the lone star tick calls home, namely the southeastern United States. But recently it’s started to spread.

The newest hot spots? Duluth, Minnesota, Hanover, New Hampshire, and the eastern tip of Long Island, where at least 100 cases have been reported in the last year. Scientists are racing to trace its spread, to understand if the lone star tick is expanding into new territories, or if other species of ticks are now causing the allergy.

RELATED: Lyme Isn’t the Only Disease Ticks Are Spreading This Summer

The University of Virginia is deep in the heart of lone star tick country. It’s also home to a world-class allergy research division, headed up by immunologist Thomas Platts-Mills. He’d been hearing tales of the meat allergy since the ’90s — people waking up in the middle of the night after a big meal, sweating and breaking out in hives. But he didn’t give it much thought until 2004, when he heard about another group of patients all suffering from the same symptoms.

This time, it wasn’t a plate of pork chops they shared; it was a new cancer drug called cetuximab. The drug worked, but curiously, patients that lived in the southeast were 10 times as likely to report side effects of itching, swelling, and a dangerous drop in blood pressure.

Platts-Mills teamed up with cetuximab’s distributor, Bristol-Myers Squibb, and began comparing patient blood samples. He discovered that all the patients who experienced an allergic reaction had pre-existing antibodies to alpha-gal, and cetuximab was full of the stuff, thanks to the genetically modified mice from which it was derived. With that mystery solved, Platts-Mills turned to figuring out what made patients so sensitive to alpha-gal.

The best hint he had was the geographic overlap between the cetuximab patients and previously reported meat allergies. The area perfectly matched where people came down with Rocky Mountain spotted fever — a disease carried by the lone star tick. But it wasn’t until Platts-Mills and two of his lab members came down with tick-induced meat allergies of their own that they made the connection.

READ MORE: Blood in a Mosquito’s Belly Could Reveal How Diseases Spread

Over the next few years Platts-Mills and his colleague Scott Commins screened more meat allergy patients and discovered that 80 percent reported being bitten by a tick. What’s more, they showed that tick bites led to a 20-fold increase in alpha-gal antibodies. Since ethics standards prevented them from attaching ticks to randomized groups of patients, this data was the best they could do to guess how meat allergy arises. Something in the tick’s saliva hijacks humans’ immune systems, red-flagging alpha-gal, and triggering the massive release of histamines whenever red meat is consumed.

Researchers are still trying to find what that something is. Commins has since moved to the University of North Carolina, where he’s injecting mice with lone star tick extracts to try to understand which molecules are setting off the alpha-gal bomb. It’s tricky: Tick saliva is packed with tons of bioactive compounds to help the parasite feed without detection. One of them might be an alpha-gal analogue — something similar-but-different-enough in shape that it sets off the human immune system. But it could also be a microbe — like a bacteria or virus — that triggers the response. Some have even suggested that residual proteins from the ticks’ earlier blood meals could be the culprit.

RELATED: Zika Isn’t the Mosquito-Borne Virus You Should Fear

Whatever it is, allergy researchers will be paying attention. Because, as far as anyone can tell, alpha-gal syndrome seems to be the only allergy that affects all people, regardless of genetic makeup. “There’s something really special about this tick,” says Jeff Wilson, an asthma, allergy, and immunology fellow in Platts-Mills’ group. Usually a mix of genes and environmental factors combine to create allergies. But when it comes to the lone star tick it doesn’t matter if you’re predisposed or not. “Just a few bites and you can render anyone really, really allergic,” he says.

In the meantime, Platts-Mills, Commins, and Wilson are busy communicating the scale of the public health problem. Every day they check local news headlines to log new cases of catastrophic hamburger aversion, and spend hours on the phone gathering the latest intel from allergy clinics and academic centers around the country. They’re building the first real red meat allergy incidence map of the U.S. — because state health departments aren’t required to report alpha-gal syndrome to the Centers for Disease Control and Prevention. And it’s still rare enough outside the southeastern US that many doctors don’t correctly diagnose it.

Wilson is trying to get blood samples from all the new outbreaks, to figure out if the patients’ antibodies correspond to the saliva of lone star ticks or a different tick species. That will tell him if the increases in the allergy are the result of changing range patterns, or if other ticks have developed the capacity to rewire human immune systems in the same way. That information would also provide further clues to the mechanism itself. As for a cure? There’s not much science has to offer on that front, besides Epipens and veggie burgers.

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Don’t know how accurate this list is, but it points out that ticks need moisture and woody environments to thrive. After 22 years in Wyoming, with my dogs running all over the desert shrub-land,  I’ve had to remove maybe 2-3 ticks.

Top 5 states for Dogs with Fleas: Arkansas, Florida, South Carolina, Alabama, Oregon Top 5 States for Cats with Fleas: Oregon. Washington, Florida, California, Alabama The least common? Semi-arid and Desert regions of the U.S. of the North, Midwest and Western states. Bottom 5 States for Dogs with Fleas: Utah, Montana, Nevada, Arizona, South Dakota Bottom 5 States for Cats with Fleas: Utah, Colorado, Nevada, Montana, South Dakota

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From people who study ticks:  https://source/wustl.edu/2012/02

Study extends the ‘ecology of fear’ to fear of parasites

Squirrels and raccoons will give up food to avoid ticks

By Diana Lutz February 24, 2012 January 13, 2016

Here’s a riddle: What’s the difference between a tick and a lion? The answer used to be that a tick is a parasite and the lion is a predator. But now those definitions don’t seem as secure as they once did. A tick also hunts its prey, following vapor trails of carbon dioxide, and consumes host tissues (blood is considered a tissue), so at least in terms of its interactions with other creatures, it is like a lion — a very small, eight-legged lion.

Ecologists are increasingly finding it useful to think of parasites, such as ticks, as micro-predators and have been mining predator-prey theory for insights into parasite-host ecology. One of those insights is that predators don’t just graze at will, and prey aren’t just so many steaks in a freezer. Instead, prey make predators work for dinner by moving elsewhere, being vigilant, flocking together or taking other defensive measures.

This notion that prey are not victims but players, as strongly motivated by fear as the predators are by hunger, is called the ecology of fear.

Work at Washington University in St. Louis, just published in EcoHealth, shows that the ecology of fear, like other concepts from predator-prey theory, also extends to parasites. Raccoons and squirrels would give up food, the study demonstrated, if the area was infested with larval ticks. At some level, they are weighing the value of the abandoned food against the risk of being parasitized.

This new understanding of the interaction between ticks and host animals has implications for human health because the ticks are vectors of several newly emerging diseases. The more we know about what determines the distributions of ticks in their environment, the better prepared we will be to avoid human exposure to these diseases.

Do host animals fear ticks?

The study’s first author, Alexa Fritzsche, collaborated with Brian Allan, PhD, now an assistant professor of entomology at the University of Illinois at Urbana-Champaign.

Is there an animal left in the wild that isn’t part of a science study?

Two young raccoons visiting a feeding tray for breakfast become unwitting participants in the study. (Credit: FRITzsche)

By the time Allan finished his postdoctoral fellowship at WUSTL, he had acquired a reputation as the tick man of Tyson Research Center, the university’s biological field station. So it was only natural that when Fritzsche, then Allan’s summer research technician, was given time to do research of her own, she decided to see if the ecology of fear extends to ticks.

Fritzsche now is a doctoral candidate in the Odum School of Ecology at the University of Georgia and is studying the role that animal behavior plays in determining the risk of parasitism

Near St. Louis, the most prevalent tick is Amblyomma americanum, called the lone star tick because the adult female has a white splotch on her back. Its larval stage heavily parasitizes small mammals, such as gray and fox squirrels and the common raccoon. Because the ticks can weaken an animal either by exposing it to pathogens or simply by consuming vast quantities of its blood, it made sense to ask whether the host animals were aware of the ticks and able to avoid them.

“It really comes down to natural selection,” Fritzsche says. “There is a cost to being parasitized, and if you don’t develop ways to detect the parasite and avoid it, you’re not going to do well in the long term.”

What will they give up to avoid ticks?

The study was designed to take advantage of the fact that lone star tick larvae (sometimes called “seed ticks”) emerge from eggs in the leaf litter in mid- to late-summer and tick densities increase as more and more ticks emerge. Larval tick densities were measured by dragging a cloth to which “questing” ticks became attached, and counting and identifying the ticks in the laboratory.

“The tick larvae are only about the size of a poppyseed,” Fritzsche says, “but they are present in such great numbers that you can look down and see a mass of them on the ground.

“When you dragged over one of these ‘tick bombs,’” she says, “the ticks could scatter across the cloth within seconds. I walked with a loop of duct-tape around my hand and as soon as I saw a mass, I’d hit the cloth with the duct tape and they’d be stuck on the tape.”

The animals’ response to the ticks (raccoons) was measured by how much food they abandoned, called the giving-up-density (GUD). This metric for assessing tradeoffs between foraging benefits and predation risks is well-established in predator-prey ecology but has only recently been used to assess the ecology of fear in host-parasite interactions.

Run for your lives

Contrary to Fritzsche’s expectations, the animals didn’t abandon the ground-level trays as soon as the ticks began to emerge. Over the course of the study, tick numbers increased — but in a patchy fashion. Some sites had only one tick per 60 square meters; others had 667.

Now, the animals began to abandon more seed from trays at sites with high tick densities regardless of whether they were on the ground or in a tree. The result suggests that the host animals may recognize the threat of parasitism and adjust their patterns of foraging accordingly.

The Center for Disease Control: reported cases of Ehrlichiosis chaffeensis, the most common of the emerging diseases carried by the lonestar tick (Amblyomma americanum). Oklahoma, Missouri and Arkansas account for 35 percent of all reported E. chaffeensis infections. The incidence of ehrlichiosis has gone steadily up since the disease became reportable in 2000 but thankfully the case fatality rate has declined. (Credit: CDC)

“We thought that they might abandon more seed on the ground than in the tree because ticks are confined to the ground, so we expected more of a local trade-off in foraging,” Allan says. “It turned out that the hosts were actually avoiding entire areas of high tick densities, suggesting potentially an even stronger response to the risk of parasitism than we initially hypothesized.”

Apparently people have underestimated both the ticks and their furry hosts, which far from blundering about obliviously, are wary of threats to their health the size of the period at the end of this sentence.

Fritzsche is willing to take the ecology of fear even farther — to include host responses to infections with micro-organisms as well as micro-predators.

Running a temperature helps some amphibians fight parasites such as viruses and fungi. As cold-blooded animals, they can’t raise their temperature on their own, but some amphibians will go to the highest rocks where the sun burns brightest to acquire a “behavioral fever” that helps them fight these illnesses.

“Some people are reluctant to attribute this level of ‘awareness’ to wild animals,” Allan says, “but ecologists have established quite clearly that prey will go to great lengths to avoid predation. Given the substantial cost of parasitism to wildlife, it wouldn’t be surprising if hosts actively adjust their behaviors to reduce this burden.”

After all, it isn’t that different from washing your hands.

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