More Reasons to Hate Ticks

“Ticks, the foulest and nastiest creatures that be. . .”

Pliny the Elder, Roman author and naturalist, 23-79, CE

“[Alpha-gal syndrome] is a severe tick-vectored food allergy. . . estimated to affect as many as 450,000 residents of the United States, yet it is not widely known.”

Diana Swift, medical journalist

What was it about ticks that ticked off Pliny the Elder? From his highly acclaimed encyclopedia, Naturalis Historia, it appears ticks’ bloodsucking behavior most offended him. Of course, in Pliny’s time (two millennia ago), no one knew that ticks had the ability to transmit a large variety of microbes that cause diseases. (The Germ Theory of Disease didn’t surface until the end of the 19th century.) If Pliny had known of this trait, his disdain for these arachnids may have turned into hatred, just as it has for a large number of Americans who live in areas of the country where ticks have a field day this time of the year.

In this week’s Germ Gems post, I focus mainly on new developments in the management of two of the most challenging tick-vectored diseases, alpha-gal-syndrome (AGS) and Lyme disease.

What are the tickborne diseases (recap). The tick season runs from spring to fall with the peak season being in the late spring and early summer. The Northeast, Mid-Atlantic and upper Midwest have the highest rates of tick borne-diseases in the U.S. If you live in one of these areas and don’t protect yourself, you’re at risk of acquiring any of these tick-borne diseases:

• Lyme Disease

• Anaplasmosis

• Babesiosis

• Ehrlichiosis

• Powassan Virus Disease

• Borrelia miyamotoi Disease

• Borrelia mayonii Disease

• Rocky Mountain Spotted Fever

Ixodes scapularis is the tick species responsible for transmitting most of the bacteria, or, in the case of Powassan fever, the virus that cause these diseases. For more information about the these diseases, how to recognize the different tick species that serve as vectors, as well as how to remove ticks safely, check out the University of Rhode Island’s superb on-line service "TickEncounter: Field Guide to Ticks.”

What’s new with AGS? AGS is one of the most unusual of all tick-borne diseases. But it isn’t an infection; instead, it is a food allergy to the molecule alpha-gal induced by a tick carrying the carbohydrate galactose-alpha-1,3-galactose (“alpha-gal”) that is found in red meat and other products made from mammals, for example, gelatin, cow’s milk and milk products. (See, “Alpha-Gal Syndrome: A Tickborne Allergy to Red Meat,” Germ Gems, August 30, 2023.)

Ixodes scapularis (the deer tick), the Western black legged tick and the lone-star tick all serve as vectors for AGS. The lone-star tick is, however, the principal vector.  If one of these ticks bites you, it can transfer the alpha-gal molecule to you making your immune system sensitive to the molecule (that is, it becomes an allergen) so that the next time your body encounters the molecule (most commonly by eating red meat), you can develop AGS—an immunoglobulin E-mediated reaction that’s potentially fatal.

In August 2023, the Centers for Disease Control and Prevention (CDC) estimated that as many as 450,000 Americans were living with AGS. While this figure may seem high, AGS has been underdiagnosed in the U.S.

According to a 2022 survey, “42% of healthcare practitioners had never heard of [AGS] and an additional 35% were ‘not too confident’ in their ability to diagnose and manage the condition.”  (See, Swift, D., “Novel Food Allergy to Tick-Borne Molecule Now More Likely to Be Diagnosed,” Medscape, March 11, 2025.) Thankfully, this may now be changing. The CDC and the University of North Carolina recently carried out a case-control study that demonstrated that AGS is more likely to be diagnosed than in past years, an improvement attributed to getting the word out to allergists, as well as other healthcare providers.

Most AGS patients can control their disease by eliminating mammal meat from their diet and avoiding tick exposure, i.e.wearing appropriate clothing and using DEET when in the woods. (Carrying an EpiPen to avoid going into sudden anaphylaxis would also be wise.) But, this is not possible for farmers, a group of people who spend their days outdoors and are particularly exposed to lone star ticks and repeated tick bites. AGS is taking a toll on them.

In her article “Another Reason to Hate Ticks,” in the October 7, 2024 issue of The Atlantic, Sarah Zhang states that the cattle’s saliva “is making some farmers allergic to their own cattle and sheep.” For farmers who are extremely sensitive to the alpha-gal molecule, “even fumes from manure, dander, and amniotic fluid can set off reactions.” According to Zhang, “Alpha-gal syndrome is forcing affected farmers to ask existential questions— not just about their identity as a farmer but about even the long-term viability of their industry.”

What’s new with Lyme disease? Lyme disease is by far the most common tick-borne disease in the U.S. According to the CDC, an estimated 476,000 people are diagnosed with Lyme disease and treated each year.

Early signs and symptoms of the disease include a bull’s eye rash, fever, headache, fatigue or flu-like symptoms. Antibiotic therapy, most commonly with oral doxycycline, is effective in more than 90% of patients. And, researchers recently screened nearly 500 Food and Drug Administration-approved compounds and identified one antibiotic (piperacillin) as a good candidate for clearing Borrelia burgdorferi, the bacterium that causes Lyme disease. (See, Lou, N., “Antibiotic Candidate for Lyme Disease Boosts Hope for Custom Approach,” MedPage Today, April 23, 2025.)

Even after the infection is cleared, some people have persistent symptoms, such as fatigue, sleep problems, and clouded thinking. Researchers are now honing in how such symptoms can persist in as many as 10-20% of patients. The National Academies of Engineering and Medicine recently convened a consensus study, “Charting a Path Toward New Treatments for Lyme Infection-Associated Chronic Illnesses,” to address the need for a better understanding of the mechanism underlying Lyme infection associated chronic illness and improved therapy.  (I discussed the potential involvement of “persistent antigens” from B. burgdorferi in the pathogenesis of Lyme infection-associated chronic illnesses in my May 4, 2024 Germ Gems post, “Neurological Manifestations of Lyme Disease.”)

There is no vaccine that prevents Lyme disease in humans…yet. But a pill may be on its way. If you own a dog or cat, chances are that at some point you’ve given your pet a flavored chewable tablet for tick prevention. Tarsus Pharmaceuticals is developing such a pill for humans that paralyzes and kills ticks. The results of a small human trial that looked promising. (See, “A Pill That Kills Ticks Is a Promising New Weapon Against Lyme Disease,” WIRED, March 16, 2024.)

It’s far too early to tell whether this experimental pill containing the drug, lotilaner, will be effective in humans. (The drug is already approved as a veterinary medicine under the brand name Credelio to control ticks and fleas in dogs and cats.) But if it’s proven safe and effective for humans, I can imagine Pliny the Elder congratulating Tarsus Pharmaceuticals by cheering: “Bravo!”