How a Tick Bite Can Give You a Red Meat Allergy — Consumer Reports
How a Tick Bite Can Give You a Red Meat Allergy
- 1 How a Tick Bite Can Give You a Red Meat Allergy
- 2 Scientists think that lone star ticks can induce an allergy to red meat. Here’s how to protect yourself.
- 3 What Recent Research Reveals
- 4 Understanding Meat Allergies
- 5 What to Watch For
- 6 About the Lone Star Tick
- 7 Protect Yourself From Ticks
- 8 Trendline
- 9 What Is a Trendline?
- 10 What Do Trendlines Tell You?
- 11 Example of How to Use a Trendline
- 12 The Difference Between Trendlines and Channels
- 13 Limitations of a Trendline
- 14 The Meat-Allergy Tick Also Carries a Mystery Killer Virus
Scientists think that lone star ticks can induce an allergy to red meat. Here’s how to protect yourself.
Most of us worry about Lyme disease or Rocky Mountain spotted fever when getting a tick bite. But different species of ticks can transmit a variety of diseases—and at least one very unusual ailment, scientists have learned: an allergy to red meat.
A growing body of evidence shows that the lone star tick—most prevalent in the southeastern U.S.—could be the cause of an allergy to a carbohydrate known as alpha-gal, which is found in red meat.
Scientists aren’t sure just how common this allergy is. But lone star ticks are spreading—their habitat now extends from the Southeast almost all the way to the Canadian border—which means more people may encounter them. Scientists who study the alpha-gal allergy estimated back in 2013 that more than 5,000 people in the Southeast U.S. alone could have the allergy.
A 2018 study in the Annals of Allergy, Asthma & Immunology suggests that a meat allergy caused by ticks may be more common than previously known, and could explain some previously unexplained cases of severe allergic reactions.
Here’s what you need to know about this allergy.
What Recent Research Reveals
Initially, scientists connected the dots between lone star ticks and meat allergies because of overlap between the geographic areas where the tick and the allergy were most common, according to an analysis published earlier this year in Annals of Allergy, Asthma & Immunology. Other studies showed that people who had the allergy tended to have a history of being bitten by ticks, or worked in jobs where they were likely to be exposed to ticks.
And in two recent cases reported in The Journal of Allergy and Clinical Immunology: In Practice, people who had an allergic reaction to red meat developed hives around the area where they had been previously bitten by a tick.
The 2018 study looked at just one allergy clinic in Tennessee, and found that in cases where they were able to pinpoint the cause, the alpha-gal allergy was behind about a third of anaphylaxis (severe allergic reaction) cases seen there between 2006 and 2016. That’s more than were caused by food allergies to peanuts, shellfish, or others, the researchers found.
Study author Jay Lieberman, M.D., associate professor at the University of Tennessee Health Science Center and vice chair of the American College of Allergy, Asthma and Immunology Food Allergy Committee, is quick to point out that these results do not mean that a third of severe allergic reactions nationwide are due to the effects of lone star tick bites, or that alpha gal is the number one cause of anaphylaxis in the country.
But Lieberman says the clinic has performed similar analyses in previous years, before the alpha-gal red meat allergy was discovered. In those earlier studies, doctors weren’t able to determine a cause for a greater percentage of anaphylaxis cases.
The newer study suggests that a significant number of those earlier cases with an unknown cause may actually have been due to this recently discovered allergy.
Understanding Meat Allergies
It’s not entirely clear to scientists why a bite from a tick could cause a person to develop an allergy to red meat, Lieberman says, or how common such an allergy is. And it doesn’t happen to everybody who’s bitten.
Only some people who’ve been bitten by lone star ticks will develop the antibodies that indicate a possible allergy to alpha-gal, a substance in red meat. Of the people who do develop those antibodies, Lieberman says, some won’t ever show symptoms of an allergic reaction to red meat.
There’s also an intriguing difference between the alpha-gal red meat allergy and every other type of food allergy. Typically, allergic reactions to food occur immediately after exposure, within a few minutes. With an alpha-gal allergy, however, a reaction typically doesn’t start until several hours after eating red meat—which can make it challenging to pinpoint the culprit.
Researchers first linked tick bites to red meat allergies almost a decade ago. But there are still a lot of questions left to answer about why some people develop the allergy and some don’t, how many people have been affected, and why the reaction to red meat is delayed, rather than immediate.
What to Watch For
Early signs of anaphylaxis may include a metallic taste, burning, tingling, or itching of the tongue or mouth, headache, and feelings of fear or confusion. A reaction can progress quickly, and severe symptoms include throat swelling, difficulty breathing, vomiting, diarrhea, and more.
If you think you may be experiencing anaphylaxis, even if you’ve never had an allergic reaction before, you should call 911. (If you know you have an allergy to food, and you experience symptoms of anaphylaxis, especially trouble breathing, wheezing, or throat swelling, you should use an epinephrine auto-injector if you have one.)
When the reaction is under control, talk to your doctor about whether red meat could have been the cause of your symptoms, since some doctors may not be aware of the alpha-gal allergy, suggests Princess Ogbogu, M.D., division director of allergy and immunology at The Ohio State University Wexner Medical Center.
There’s no cure for red meat allergy, so if you’re diagnosed, you’ll need to avoid the foods that trigger a reaction. Commonly, that includes various kinds of red meats. But some people can also become sensitive to other items that contain alpha-gal, including dairy, and even, rarely, sweets that contain gelatin or medications derived from animal byproducts.
In some cases, Lieberman says, if people who’ve developed alpha- gal allergies avoid all future tick bites from lone star ticks (or the varieties that cause the allergy in other countries), their levels of the antibodies to alpha-gal may diminish, and the allergy could subside. It’s unknown how common this is, however.
About the Lone Star Tick
Lone star ticks, so named for the white splotch on the backs of adult females, are most common in southern and eastern states. Like other ticks, however, their geographic distribution is expanding, according to Ellen Stromdahl, a retired entomologist from the tickborne disease laboratory of the U.S. Army Public Health Center in Aberdeen Proving Ground, Md.
Lone star ticks don’t cause Lyme disease, as a recent analysis that Stromdahl conducted shows. But along with spreading the alpha-gal allergy, they can also transmit the bacteria that cause another disease called ehrlichiosis. Ehrlichiosis can cause fever, muscle pain, nausea, vomiting, and, rarely, rash. It’s fatal in about 1.8 percent of cases, according to the Centers for Disease Control and Prevention, although it can be treated with antibiotics.
A lone star tick is much less likely to carry ehrlichiosis than a blacklegged tick is likely to carry Lyme disease, notes Stromdahl. But lone star ticks are much more aggressive than other common types of ticks in the U.S. “You’re more likely to be mobbed by lone star ticks,” she says, and finding multiple bites is common if you’ve been in their habitat.
Protect Yourself From Ticks
As with any tick bite, it’s important not to panic if you discover one, Lieberman says. “The vast majority in this country and elsewhere who get bitten by ticks don’t develop alpha-gal allergy,” he says.
Still, you can take reasonable precautions to protect yourself from ticks and the diseases—or allergies—they can cause. Here’s what to do:
Wear an effective bug spray if you’re going to be in an area where ticks are common. Lone star and other types of ticks prefer wooded areas, brush, and long grass. Consumer Reports’ insect repellent testing has found that products containing 25 to 30 percent deet provide the most reliable protection. (Check out our top-rated repellents.)
Dress carefully. Wear long pants and long sleeves, and tuck your pants into your socks. Wearing clothing commercially treated with the pesticide permethrin, or treating your clothes and gear with permethrin yourself, is also a good option for additional protection.
Check yourself for ticks at the end of every day you’ve been out in their territory. Taking a shower soon after you come in is a good opportunity to wash away any ticks that may be crawling on your skin without having yet bitten you, and to carefully look for any that have attached. If you find them on you, remove them properly.
Be careful with the clothes you were wearing in tick habitats, Stromdahl recommends. Run them through a cycle in a hot dryer to kill any ticks that may be clinging on, and leave your shoes outside in the sun.
What Is a Trendline?
A trendline is a line drawn over pivot highs or under pivot lows to show the prevailing direction of price. Trendlines are a visual representation of support and resistance in any time frame. They show direction and speed of price, and also describe patterns during periods of price contraction.
- A single trendline can be applied to a chart to give a clearer picture of the trend.
- Trendlines can be applied to the highs and the lows to create a channel.
- The time period being analyzed and the exact points used to create a trendline vary from trader to trader.
What Do Trendlines Tell You?
The trendline is among the most important tools used by technical analysts. Instead of looking at past business performance or other fundamentals, technical analysts look for trends in price action. A trendline helps technical analysts determine the current direction in market prices. Technical analysts believe the trend is your friend, and identifying this trend is the first step in the process of making a good trade.
To create a trendline, an analyst must have at least two points on a price chart. Some analysts like to use different time frames such as one minute or five minutes. Others look at daily charts or weekly charts. Some analysts put aside time altogether, choosing to view trends based on tick intervals rather than intervals of time. What makes trendlines so universal in usage and appeal is they can be used to help identify trends regardless of the time period, time frame or interval used.
If company A is trading at $35 and moves to $40 in two days and $45 in three days, the analyst has three points to plot on a chart, starting at $35, then moving to $40, and then moving to $45. If the analyst draws a line between all three price points, they have an upward trend. The trendline drawn has a positive slope and is therefore telling the analyst to buy in the direction of the trend. If company A’s price goes from $35 to $25, however, the trendline has a negative slope and the analyst should sell in the direction of the trend.
Example of How to Use a Trendline
Trendlines are relatively easy to use. A trader simply has to chart the price data normally, using open, close, high and low. Below is data for the Russell 2000 in a candlestick chart with the trendline applied to three session lows over a two month period.
The trendline shows the uptrend in the Russell 2000 and can be thought of as support when entering a position. In this case, trader may choose enter a long position near the trendline and then extend it into the future. If the price action breaches the trendline on the downside, the trader can use that as a signal to close the position. This allows the trader to exit when the trend he or she is following starts to weaken.
Trendlines are, of course, a product of the time period. In the example above, a trader doesn’t need to redraw the trendline very often. On a time scale of minutes, however, trendlines and trades may need to be readjusted frequently.
The Difference Between Trendlines and Channels
More than one trendline can be applied to a chart. Traders often use a trendline connecting highs for a period as well as another to connect lows in order to create channels. A channel adds a visual representation of both support and resistance for the time period being analyzed. Similar to a single trendline, traders are looking for a spike or a breakout to take the price action out of the channel. They may use that breach as an exit point or an entry point depending on how they are setting up their trade.
Limitations of a Trendline
Trendlines have limitations shared by all charting tools in that they have to be readjusted as more price data comes in. A trendline will sometimes last for a long time, but eventually the price action will deviate enough that it needs to be updated. Moreover, traders often choose different data points to connect. For example, some traders will use the lowest lows, while others may only use the lowest closing prices for a period. Last, trendlines applied on smaller timeframes can be volume sensitive. A trendline formed on low volume may easily be broken as volume picks up throughout a session.
The Meat-Allergy Tick Also Carries a Mystery Killer Virus
On May 31, 2017, 58-year-old Tamela Wilson checked into Barnes-Jewish Hospital, in St. Louis, with a fever, fatigue, and a strange red rash. She’d been undergoing chemotherapy to treat a relapsing lymphoma, but this exhaustion wasn’t just the cancer or the drugs. She told the doctors she worked at nearby Meramec State Park, tending to its miles of trails through forested river bluffs. And that while there, a week before her symptoms started, she found two ticks burrowed into her body.
Wilson’s doctors tested her blood for Missouri’s common tick diseases. On day three, when the results came back negative, they sent a vial to Fort Collins, Colorado, to the Centers for Disease Control and Prevention’s Division of Vector-Borne Diseases, for a more extensive analysis. On day 10, they got their answer: Bourbon virus. Thirteen days later she was dead.
At the time, Wilson was one of only a handful of people in the world to ever be diagnosed with a Bourbon virus infection, and the second to succumb to the mysterious microbe since it was discovered in 2014. Two years later, the strain of virus that once coursed through Wilson’s veins lives on in freezers and petri dishes a few buildings over from where she died, as researchers race to find possible treatments for the next time.
Scientists know almost nothing about how Bourbon virus behaves or how it got here or where it will show up next. But they have learned enough to know they haven’t seen the last of it.
What they fear most is that the virus could be silently spreading through human populations, getting noticed only when it causes severe symptoms in an unlucky few. That’s what’s started to happen with another new tick-borne virus in Missouri. If Bourbon virus were to establish itself there in humans too, the chances go up that more cases, like Wilson’s, will turn deadly. And until someone conducts the necessary studies, there’s no telling how far the virus has spread or how many people might potentially be in danger.
Under a microscope, Bourbon virus is a shape-shifter, sometimes long and filamentous, sometimes a sphere studded with spiky proteins, encapsulating a string of segmented genetic code. It’s the only human pathogen of the genus Thogotovirus to make it to the New World. Its nearest evolutionary relatives are viruses found in the bodies of sheep-sucking ticks in Kyrgyzstan and camel-chewing ticks in India, both of which attack neurons and cause brain inflammation when transmitted to humans. Bourbon virus appears to have developed a taste for other types of human cells during its travels; in the few documented cases that have appeared in the US, patients have experienced massive declines in their white blood cell populations.
Like its closest cousins, Bourbon virus seems to spend at least some of its time in ticks. The patient the virus was first isolated from—a 68-year-old man named John Seested in Bourbon County, Kansas—had a history of tick bites. The summer after its discovery there, CDC researchers found the virus in the bodies of several ticks collected elsewhere in Bourbon County. The species they found carrying the virus was the Lone Star tick, whose bite is more notorious for making people allergic to red meat. It’s also been shown to replicate inside tick cell lines in the lab.
But the CDC has yet to formally declare Bourbon virus a tick-borne disease. To definitively link Bourbon virus with its suspected vector, the agency needs more data—specifically on how well Lone Star ticks acquire, maintain, and transmit the pathogen in a lab. Aaron Brault, a microbiologist with CDC’s Division of Vector-Borne Diseases, says those studies are currently in progress. He says it’s now a “strong probability rather than simply a possibility” that the virus is transmitted to humans through ticks.
Jacco Boon, a virologist at Washington University whose lab is located on the same block as Barnes-Jewish, the university teaching hospital, had lots of other questions. “But the first thing I wanted to know was ‘could this virus be treated?’” he says. Wilson’s infectious disease doctors reached out to their colleague because Boon studies a distantly related cousin to Bourbon virus—influenza. And he had a hunch that an experimental drug that curbs influenza’s ability to replicate might work on this enigmatic emerging virus too.
Within a month of Wilson’s death, Boon’s team had cultured her strain and used it to infect human cells in petri dishes. They watched as the virus torpedoed through the stained cells, hollowing out clear craters on the plate’s purple surface. But when they added a drug called favipiravir to infected cells, they survived. And the amount of Bourbon virus circulating in the culture plummeted nearly a million-fold.
Favipiravir is shaped like a nucleotide, the backbone building block of DNA and RNA. Viruses steal a cell’s nucleotides to make more copies of itself, using a special enzyme as their engine of self-replication. When that enzyme grabs favipiravir instead of a nucleotide, the virus’s multiplication machinery gets gummed up and grinds to a halt. The drug is available as a flu treatment in Japan, where it was developed, but has not yet been approved in the US. Boon’s team found that the drug also had a protective effect in mice with compromised immune systems, leading to a 100 percent survival rate. Compromised mice that didn’t get the drug all died within a week of infection (normal mice are not susceptible to Bourbon virus). It’s not proof that the drug works in humans, but the data, published last month, is the first to suggest Bourbon virus has a chemical vulnerability that doctors could try to exploit in the future.
Boon had planned to devote his life’s work to influenza. But since Bourbon virus struck in his backyard, his lab is now central to unraveling the pathogen’s many riddles. In addition to Wilson’s strain he’s since acquired other clinical samples, including from patient zero. Seested and Wilson are the only known fatalities to date, and though they came in with similar symptoms, they deteriorated in strikingly distinct ways at the end. Understanding how the virus varies genetically may help explain who it infects, and even track its origins beyond its abrupt arrival in Seested’s body in 2014.
To get at his biggest questions, Boon is now trying to set up studies to test the blood of lots of people in Missouri and Kansas for antibodies to Bourbon virus and assess how many of them have ever been exposed to it. That will reveal whether the disease is rare and typically deadly, or if it’s actually more common and mostly innocuous with lethal outcomes being the outliers. According to the CDC, there have been no reports of the virus anywhere outside the US. “You don’t have to go to the Congo to find emerging viruses,” says Boon.
Since 2004, seven diseases believed to pass from ticks to humans surfaced for the first time on US soil, including Bourbon virus. According to a 2018 CDC report, the pace of emergence of new, obscure, and dangerous vector-borne pathogens appears to be increasing. Some scientists counter that this alarming trend may just reflect advances in DNA-based diagnostics that can pick out previously unknown viruses and bacteria that have actually been sickening people (and confounding doctors) for a while. But as climate change, suburban sprawl, and increased international travel are putting more ticks and the pathogens they carry in the paths of humans, what’s becoming more urgently apparent is how the US’s tick monitoring systems are not keeping pace.
“It’s really a patchwork in terms of the effort that different areas are putting into surveillance,” says Becky Eisen, a tick biologist with CDC’s Division of Vector-Borne diseases. The federal public health agency maintains national maps of the ranges of different tick species, but they’re extrapolated from scattered data collected in large part by academic researchers. Only a few states, mostly in the Northeast, have dedicated tick surveillance and control programs. That leaves large parts of the country in a data blackout.
To help address that problem the CDC is funding an effort to identify the most urgent gaps in surveillance. It has also begun publishing guidance documents for public health departments on how to collect ticks and test them for diseases, to encourage more consistent data collection across different states and counties.
In an ideal world, says Eisen, every county in the US would send a few well-protected people out into fields and forests every spring and summer, setting traps or dragging a white flannel sheet between them to collect all the ticks making their homes in the grasses and underbrush. Their precise numbers, locations, and species would be recorded so that later on when they get ground up and tested, that DNA would paint a national picture of risk for exposure to every tick-borne pathogen in America. But she recognizes that would be incredibly labor-intensive, and with only so many public funding dollars to go around each year, there are always competing priorities.“But from a research perspective, that’s the kind of repeatable, consistent data we’d really want,” says Eisen. “That would be the dream.”
For now though, she’ll take what she can get. The CDC recently changed the way it funds state health departments, allowing local agencies more flexibility to put the money toward tick-tracking projects if they so choose. It still might not be enough. In Missouri, for example, the state has started to spend more of its allotted CDC funds on combating tick-borne disease—$76,471 in 2018 compared to $22,624 in 2017. But according to a Missouri health department spokesperson, the state focuses its efforts not on surveillance but on education and awareness campaigns. Sending people out into fields is expensive, and not always satisfying. In the months after Wilson’s death, as Boon’s lab was working to grow more copies of the virus, Missouri’s department of health sent teams of researchers into Meramec State Park to look for copies in the wild. After collecting and testing more than 7,000 ticks, no trace of Bourbon virus was found.
07/09/19 8:40pm EST An earlier version of this story misstated the requirements for mandatory release of infectious disease data to the CDC.