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Dispatches : Science

Deciphering Lyme Disease

Though antibiotics can often clear up symptoms of Lyme disease within a few weeks, some patients experience severe symptoms like nervous system abnormalities, heart rhythm irregularities, and arthritis weeks or even months after infection. At this point, scientists don’t yet completely understand the exact cause of the longer-term symptoms, and they aren’t easy to treat.

But new research out of Johns Hopkins and Stanford University could lay the groundwork to help determine which Lyme disease patients develop post-treatment Lyme disease syndrome (PTLDS), a little-understood and controversial disease.

To investigate, researchers at Hopkins set out to identify the biological “signatures” of particular immune system molecules called mediators; the idea was to determine which parts of the immune response are mobilized in reaction to the disease, particularly in the beginning, when patient symptoms are most acute.

After studying the levels of 65 different molecules, the team’s analysis found two different groups of Lyme disease patients in the early stages of infection: “mediator-high” and “mediator low.” Those in the high-mediator group exhibited more severe symptoms, higher rates of antibody production, and higher liver enzymes before treatment.

They also showed higher levels of three particular mediators, which returned to normal after treatment. Researchers found that patients in the mediator-low group seemed to have been unable to mount a strong immune response to the disease.

The levels of particular mediators and their receptors may be important biomarkers for Lyme disease that could be linked to individual symptoms.

“With this signature in hand we can begin to ask in larger numbers of patients if all or part of this signature stays elevated in some and if these can be related to PTLDS,” says Mark Soloski, senior author of the report and a professor of medicine at Hopkins.

“These biomarkers have the potential to provide insight into disease process but also may be of value in predicting who may develop PTLDS as well as suggest pathways that can be targeted for therapy.”

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Why a Downhill Runner Will Always Win Boston

As accomplished and legendary a U.S. marathoner as has ever competed, Frank Shorter (Olympic marathon gold medalist in 1972) never won Boston. In fact, he never even cracked the top three. On the other hand, the equally legendary Bill Rodgers won the Boston and New York City marathons four times but finished a disappointing 40th in the 1976 Montreal Olympic marathon. And since 2002, either a Kenyan or Ethiopian has won Boston—with Kenyan Geoffrey Mutai setting the course record of 2:03:02 in 2011. 

Some people make the grade in Boston—literally; others don’t.

“Bill Rodgers was made to run Boston because he’s a downhill runner,” says Shorter, 66. “And what Mutai has shown is that he, biomechanically, moves in a way that allows him to run downhill really well.”

Biomechanically, downhilling involves greater ground reaction forces and therefore induces more stress on the tissues of the leg; it also requires less metabolic energy. Meaning, “the energy required to support any speed is substantially reduced when running downhill,” says Peter Weyand, associate professor at Southern Methodist University’s Department of Applied Physiology and Wellness. Basically, figuring out a downhill pace that feels best for you is the best way to avoid wear and tear, and hence, fatigue.

Physiologically, the bigger you are, the harder you hit the ground. “Since the force at any running speed and incline is set by the body’s weight, gaining or losing weight will increase or decrease the forces on the ground and therefore also experienced by the tissues of the feet, joints and legs,” explains Weyand. “So, if all other factors are equal, being lighter would tend to lessen the pounding a runner sustains at any downhill running speed.”

One of the Boston’s biggest challenges is that its downhill sections come late in the race (the net drop from its start in Hopkinton to the finish is 400 feet), when the legs are more susceptible to stress-induced damage from all the prior miles. Weyand therefore hypothesizes that “the better downhill runners are more willing or able to absorb the pounding—or both.”

More willing and able because they train that way. “My training is very up and down all the time,” says Mutai, who feels it helps to have strong upper legs but whose training probably isn’t all that different from his Kenyan and Ethiopian peers. “So running on hills is normal for me.”

As it was for Rodgers, whose high school coach told him to lean forward and use his momentum when going downhill. “It’s also a time many runners assume is a recovery period—after an uphill—so strategically it can be a decisive move many runners do not want to follow,” says Rodgers, 66, who has always viewed racing as psychological as much as physical. “Breaking way is the name of the game if you’re competing, and in road racing, hills play a crucial role.”

Still, it’s not all psychological. As Weyand says, “The physics cannot be fooled—the ground forces involved are set by a runner’s body weight and speed. The faster one runs, the great the ground forces. The steeper the downhill, the greater the forces are at any speed.” 

Which is why Boston is so physically taxing. “Boston left my legs more sore than any other marathon course,” says Rodgers, who doesn’t see any particular body type as being better suited to hills than any other.

“There are so many grades and hills, but I saw them as key opportunities,” says Mutai, who won’t be running Boston this year. “Think of them in a positive light. As a chance to shift gears, and a time to run away from your competition.” 

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The Scariest Tick Disease You Haven't Heard Of

There are plenty of reasons to fear ticks—Lyme disease, Rocky Mountain Spotted Fever, general aversion to blood suckers. Here's another one to add to the list: severe and sudden allergies to red meat.

In September, Norman was camping with her husband in Falls Creek Falls Tennessee. At 3 a.m., she woke up with hives. She and her husband drove five miles to get cell service, and the 911 operator they called told them to stay put. "By the time the ambulance got there my throat was pretty closed up, and I had hives completely," Norman says. "They told me I would not have made it if we had driven."

The cause of the reaction? A tick that had bitten her six weeks earlier and a steak she'd eaten for dinner that night.

Across the American Southeast, and in parts of Europe and Australia, doctors are treating patients with sudden, potentially fatal allergies to red meat that researchers believe are caused by bites from specific types of ticks. In the U.S., it's the Lone Star Tick.

"These bites are really common, especially in places where there are tons of these ticks, in the Southeast particularly," says Dr. Robert Valet, an assistant professor of medicine at Vanderbilt University. "The vast majority of people don't get this. But it is on the list of things that can come from tick bites."

Here's how researchers believe it works: When a Lone Star tick bites a person, it introduces something called alpha-gal sugar into the bite. Some bitten patients become allergic to the sugar, which is also found in red meat. For those patients, eating alpha-gal can cause hives, lip or tongue swelling, or anaphylaxis, a potentially deadly allergic reaction that can cause the throat to close or blood pressure to drop.

Symptoms tend to appear four to six hours after eating red meat, and sometimes even dairy, and reactions tend to occur weeks or even months after a patient was bitten.

"Within the Southeast…it's up there with peanut allergies and shellfish allergies," Valet says. About one percent of the patients who visit the Vanderbilt Asthma, Sinus and Allergy Clinic are coming in with the allergy. Dr. Platts-Mills, who lead the UVA study and has the allergy himself, told NPR that this particular tick is "very aggressive. Its larval forms will bite humans, whereas none of the other American tick larvae will do that."

If you're wondering why you've never heard of it, researchers at the University of Virginia published the first study linking ticks to the allergy in 2009. "We've really only been testing for it in the last couple of years," Valet says.

It's also fairly rare in comparison to other tick-borne disease like Lyme disease, which reports about 25,000 new cases a year; so far, UVA has recorded only about 1000 cases of the tick-related allergy.

But that doesn't mean there's no reason to be careful, particularly if you live or hike in areas of Tennessee, Virginia, or North Carolina, though Lone Star Ticks can be found as far north as Maine and as far West as Nebraska—and bit-related allergies have been reported in states like New York and .

There's also no cure. Beyond carrying an Epipen and trying to avoid ticks to begin with, there's not a lot you can do. Though some allergies do go away on their own, it's a safe bet that most people who get it won't be eating red meat again, and some like Norman—about 30 percent of those with the allergy—are also allergic to dairy. In severe cases, it can also cause an allergy to gelatin.

But this isn't the kind of disease you need to get tested for. "It's kind of one of those things that will happen and it will be obvious," Valet says.

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