Archive for the ‘Ticks’ Category

Seropositivity to Tick Endosymbiont As A Marker To Determine Tick Bite Exposure

Seropositivity to Midichloria mitochondrii (order Rickettsiales) as a marker to determine the exposure of humans to tick bite.


Ixodes ricinus is the most common tick species parasitizing humans in Europe, and the main vector of Borrelia burgdorferi sensu lato, the causative agent of Lyme disease in the continent. This tick species also harbors the endosymbiont Midichloria mitochondrii, and there is strong evidence that this bacterium is inoculated into the vertebrate host during the blood meal. A high proportion of tick bites remains unnoticed due to rarity of immediate symptoms, implying the risk of occult tick-borne infections in turn a potential risk factor for the onset of chronic-degenerative diseases. Since suitable tools to determine the previous exposure to I. ricinus bites are needed, this work investigated whether seropositivity toward a protein of M. mitochondrii (rFliD) could represent a marker for diagnosis of I. ricinus bite.

We screened 274 sera collected from patients from several European countries, at different risk of tick bite, using an ELISA protocol. Our results show a clear trend indicating that positivity to rFliD is higher where the tick bite can be regarded as certain/almost certain, and lower where there is an uncertainty on the bite, with the highest positivity in Lyme patients (47.30%) and the lowest (2.00%) in negative controls.

According to the obtained results, M. mitochondrii can be regarded as a useful source of antigens, with the potential to be used to assess the exposure to ticks harboring this bacterium. In prospect, additional antigens from M. mitochondrii and tick salivary glands should be investigated and incorporated in a multi-antigen test for tick bite diagnosis.



This is an interesting study with future potential. Essentially they are saying since Lyme is so hard to detect – find its friends and you may find Lyme.

I’ve written about endosymbionts before, particularly Wolbachia:

Briefly, endosymbionts are organisms living in the body or cells of another organism in a symbiotic relationshipwhich isn’t always of mutual benefit. An example of a mutualistic relationship is the protozoan endosymbionts inside a termite which help it to break down the wood it eats.
However, in the case of Wolbachia, while the benefit between itself and the worms it lives in may be mutualistic, it’s caused harm in dogs being treated for heart worm. Heart worm medication causes Wolbachia to be released into the blood and tissues causing severe Inflammation in pulmonary artery endothelium which may form thrombi and interstitial inflammation. Wolbachia also activates pro inflammatory cytokines. For human Lyme/MSIDS patients this could translate out to a similar result when they are treated for worms, which ticks also carry.
What I find interesting here is that both Midichloria and Wolbachia are in the same subclass of Rickettsidae and order Rickettsiales. Guess who else is in these groups?
  • Rickettsia
  • Ehrlichia
Both of which cause a variety of human and animal illness.

The question of course is, could these supposedly harmless endosymbionts be responsible for more than they are given credit for? Testing for them may not only reveal that Lyme is present but in fact that they are contributing to the problem. Sounds like an exciting field of discovery.

Heartland Virus Detected in Ticks From Kankakee County, Illinois

Heartland virus detected in ticks from Kankakee County, Illinois

August 17, 2019
By NewsDesk  @infectiousdiseasenews

In a follow-up on the report of a Heartland virus case reported in a Kankakee County, Illinois resident last year,  the Illinois Department of Public Health (IDPH) collaborated with the Illinois Natural History Survey Medical Entomology Laboratory (INHS MEL) and Kankakee County Health Department to conduct the first environmental health investigation to a novel tickborne disease case and found Heartland virus was detected in Lone Star ticks collected from Kankakee County.

Amblyomma americanum–The Lone Star Tick/CDC

Bites from Ticks can result in multiple types of infections, which can cause serious illness in some people,” said IDPH Director Dr. Ngozi Ezike. “It is important to take precautions and protect yourself from tick bites by using insect repellent and checking regularly for ticks when in wooded areas or high grass.”

Heartland virus was first identified in 2009 when two Missouri farmers who had been bitten by ticks were admitted to a hospital. Heartland virus is a viral disease that can be spread to people through the bite of an infected Lone Star tick. Reported cases of Heartland virus disease are relatively rare, however almost all individuals with Heartland virus have been hospitalized. Although most people infected have fully recovered, a few have died. There are no vaccines to prevent Heartland virus infections.

Signs and symptoms of infection are similar to those of other tickborne diseases and can include fever, headaches, fatigue, muscle aches, and diarrhea. Most people have reported becoming sick about two weeks after being bit by a tick. And while there is no treatment, doctors can treat some of the symptoms. If you have been bitten by a tick and think you may have Heartland virus or another tickborne illness, visit a health care provider. Other tickborne illnesses Illinois residents have been diagnosed with include Lyme disease, Rocky Mountain Spotted Fever, Ehrlichiosis, and tularemia. Health care providers should consider Heartland virus in patients who have compatible symptoms and are not responding to other treatments.

Ticks are commonly found on the tips of grasses and shrubs. Lone Star ticks are found throughout Illinois. Ticks crawl―they cannot fly or jump. The tick will wait on the grass or shrub for a person or animal to walk by and then quickly climb aboard. Some ticks will attach quickly and others will wander, looking for places like the ear, or other areas where the skin is thinner.

Simple tips to avoid tick bites include:

  • Wear light-colored, protective clothing—long-sleeved shirts, pants, boots or sturdy shoes, and a head covering. Treat clothing with products containing 0.5 percent permethrin.
  • Use Environmental Protection Agency (EPA)-registered insect repellents containing DEET, picaridin, IR3535, or Oil of Lemon Eucalyptus (OLE).
  • Walk in the center of trails so grass, shrubs, and weeds do not brush against you.
  • Check yourself, children, other family members, and pets for ticks every two to three hours.
  • Remove any tick promptly by grasping it with tweezers, as close to the skin as possible and gently, but firmly, pulling it straight out. Wash your hands and the tick bite site with soap and water.


For more:

Alpha-Gal Syndrome: How to Diagnose, Treat, and Prevent the Tick-Borne Red Meat Allergy

Alpha-Gal Syndrome: How to Diagnose, Treat, and Prevent the Tick-Borne Red Meat Allergy

Alpha-Gal Syndrome: How to Diagnose, Treat, and Prevent the Tick-Borne Red Meat Allergy

By Jenny Lelwica Buttaccio
Posted 8/6/19

Jennifer Burton lives in a subdivision in Northwest Arkansas on more than two acres of well-maintained land — all except for the one part which contains poison ivy that she can’t get rid of, she jokingly says. Burton loves to garden, and 1.5 acres of her property are fenced off for her plants and birds; she has fruit trees, berry vines, chickens, and guinea fowl.

“My husband Eric used to spray the yard with insect repellent, but once we got the chickens and guinea fowl, we stopped spraying,” says Burton. “They are great tick eaters, but they are also very noisy.”

Behind Burton’s subdivision is a heavily wooded area, so coming in contact with ticks — especially lone star ticks, which are widely distributed across the southeastern and eastern U.S. — isn’t uncommon for her. “Lone star ticks are the most aggressive ticks I’ve ever seen. They hunt in packs, crawling like a bunch of ants,” Burton describes.

lone star stick on finger, over white background

Burton is well-acquainted with the tactics lone star ticks use to seek out hosts. She’s been bitten many times over the past several years — first in 2011, then again in 2013, and most recently in 2016.

For Burton, 2016 also brought about an eight to nine-month assault of symptoms, including itchy hives, gastrointestinal issues, and vomiting. Doctors chalked up her escalating symptoms to an irritable bowel syndrome (IBS)diagnosis they found in her medical chart from years before, “possible” food allergies, or something she was eating.

By 2017, Burton had experienced four anaphylactic reactions approximately three weeks apart from one another. The last one brought her close to death. “It was almost like something was building up in my body,” she says.

Then, her husband, who’d been a consistent source of strength and support for her, got fed up with the lack of a diagnosis and effective treatment and hit a breaking point. “He insisted that our primary care doctor do something because he wasn’t going to watch me die,” Burton says. Finally, her doctor agreed to perform allergy testing; when the results came back, she learned she was highly allergic to beef and dairy, and mildly allergic to peanuts, despite having no history of such food allergies.

Her doctor was at a loss. Indeed, though news headlines about a dangerous meat allergy had begun to splash across the pages of nearly every major publication, most doctors knew little about it, its origins, or the severe, widespread symptoms it could induce.

Eventually, Burton saw allergist and immunologist, Tina Merritt, MD, an expert in alpha-gal syndrome (AGS) in Bentonville, Arkansas. Dr. Merritt was able to accurately diagnose Burton with AGS, and she traced the onset of the illness back to Burton’s history of lone star tick bites.

“Lone star ticks are the most aggressive ticks I’ve ever seen. They hunt in packs, crawling like a bunch of ants.”

Today, Burton runs the Alpha Gal Encouragers nonprofit, an advocacy, outreach, and support group for those diagnosed with AGS, and she estimates she feels about 90% most days. But her life is far from normal: On her wrist, she wears an emergency alert bracelet, which reads, “Anaphylaxis.” Everywhere she goes, she brings six EpiPens, two inhalers, and Unisom Sleep Melts because it’s a fast-acting antihistamine that doesn’t contain any mammal ingredients.

“I still have stomach issues. I’m not as active as I would like to be — my sweat makes my skin itchy. So, there are things I’m a little bit more restricted with, but I’m doing okay. Finally, I came to the realization that I have to live with this,” she says.

And with no cure in sight for AGS, Burton always has a flashlight and a tick key on hand for a swift tick removal if necessary. She knows that, for now, avoiding more tick bites is her best defense.

What is Alpha-Gal?

Alpha-gal is an abbreviated name for a sugar molecule that’s found in many mammals, with the exception of humans and primates like apes and monkeys. The sugar’s full name is galactose-α-1,3-galactose, and for most people, it doesn’t pose a health threat.

alpha gal chemical structure, scientific image

But for people like Burton, who have developed AGS, their bodies react to the molecule with an exaggerated immune response to red meat like beef, pork, venison, or lamb. (Burton suspects her mild reaction to peanuts might be linked to some manufacturers using gelatin — a mammalian ingredient — to preserve their peanuts.) Sometimes, the immune response produces mild, allergy-type symptoms. Other times, life-threatening, anaphylactic reactions can occur.

AGS is thought to be the result of a tick bite by the lone star tick, a bloodsucking arachnid that’s fairly easily recognized: Females have a single white dot in the center of a brown body, while males have white spots or streaks around the outer edge of the body.

“It was almost like something was building up in my body.”

Unlike with ticks that transmit Lyme disease and coinfections, however, a lone star tick doesn’t have to be attached to its human host for any length of time — alpha-gal is present in tick saliva, which means an immune response can be triggered right as the tick bites you. In addition to alpha-gal, lone star ticks can carry other tick-borne infections like Rocky Mountain Spotted Fever, Ehrlichiosis, Rickettsia, and more.

But as with all things tick-related, the lone star tick and alpha-gal are spreading across other parts of the country and beyond. Cases of the illness have also been reported in Australia, Asia, Central America, Europe, Japan, and South Korea, though the illness is likely to come from different tick species in other parts of the world.


skin rash across female back from food allergy

Many food allergies have a rapid onset — think shellfish or peanut allergies. But alpha-gal is different, which can complicate the process of getting a proper diagnosis. Typical reactions to the sugar were delayed by at least two hours, with the majority of people experiencing reactions three to six hours after consumption, suggests a review in the journal Current Allergy and Asthma Reports.

Allergy symptoms associated with alpha-gal include:

  • Skin rashes like hives or eczema
  • Itching
  • Facial swelling, especially the lips, eyelids, tongue, or throat
  • Swelling in other parts of the body
  • Difficulty breathing or shortness of breath
  • Wheezing or coughing
  • Digestive upset, including abdominal pain, cramping, and diarrhea
  • Nausea and vomiting
  • Nasal allergy symptoms like runny nose and sneezing
  • Feeling faint or dizzy
  • Headaches
  • Low blood pressure
  • Anaphylaxis (a severe and sudden allergic reaction that requires immediate treatment)

To further compound the problem, alpha-gal reactions may not be confined to red meat allergies alone. People can be allergic to a variety of mammalian products: dairy products, gelatin, lanolin (found in cosmetics and personal care products), magnesium stearate, and certain vaccines and medicationscan pose a serious problem to the community of people with AGS. With a delayed immune response, it can be difficult to pinpoint the culprit that’s making you sick.

Testing and Diagnosis

An allergist or other healthcare professional will gather your health history and information about your symptoms and potential exposure to ticks. They can diagnose AGS through a blood test, which looks at the IgE antibodies to alpha-gal in your blood. They can also use a skin prick test to determine if you’re allergic to specific foods like red meat found in beef, pork, or lamb.


There is no cure for AGS, but avoiding red meat and other mammalian products can help reduce the incidence of reactions. Also, keep in mind that alpha-gal can be found in a variety of other products. It’s important to read labels on all the products you consume and use for ingredients that could be derived from red meat.

You may need to carry prescription epinephrine (like EpiPens) and other antihistamines with you at all times. Though the symptoms of AGS can wax and wane, you’ll need to try your best to avoid further tick bites and reduce the chances of worsening your immune system’s response to the molecule.


man spraying natural tick repellant on his skin, outdoor background

Since there is no cure for AGS, the best way to avoid contracting it is through preventing tick bites. Ultimately, an aggressive approach to prevention is key to protecting you and your family from a multitude of tick-borne diseases. Here’s what you need to know:

  1. Familiarize yourself with your outdoor surroundings. Be on the lookout for tick-friendly habitats like tall grasses, overgrown or unkempt grass, areas covered in brush, piles of leaf litter, and your pets.
  2. Protect exposed skin with tick repellant. Repellents like DEET, picaridin, and oil of lemon eucalyptus (OLE) are safe to use on adult skin.
  3. Use permethrin on clothing and outdoor gear. Permethrin is an insecticide that kills ticks. The CDC recommends products that contain 0.5% of permethrin to help you protect yourself. Follow the instructions on the bottle, and use it on clothing, shoes, and outdoor gear.
  4. Protect your pets. To find the right products, consult with your veterinarian, and use the product according to the instructions. Regularly grooming your pet, finding the right flea and tick collar, and maintaining your lawn can help keep you and your pet safe.
  5. When you return from being outdoors, take a shower. Showering right away can wash away ticks that are crawling on you before they attach, and it can help you find and remove attached ticks, reducing your risk of contracting Lyme disease and other tick-borne infections that take longer to transmit.
  6. Look for ticks on yourself and your family. Perform tick checks on yourself, your family, and your pets when you come in from the outdoors. Remember to investigate more concealed areas of the body.
  7. Promptly remove any ticks that have latched on. Use a pair of fine-pointed tweezers to firmly pull the tick straight out of the skin, then disinfect the bite with soap and water. Watch for signs of any tick-borne infection and follow-up with your doctor.

For a more comprehensive guide, visit 7 Steps to Preventing Lyme and Other Tick-Borne Diseases.

“Ultimately, I wish people would take tick prevention seriously. Don’t get bit. Don’t get sick.”

Further Reading and Research to Help You Cope

Coping with alpha-gal is challenging, to say the least. But knowing where to look for help and advice when you’re forced to make abrupt lifestyle changes can be lifesaving. Fortunately, there are some organizations and resources available, so you don’t have to go at this alone.

  • Alpha Gal Encouragers: A faith-based 501(c)(3) founded by Jennifer Burton in Northwest Arkansas with a mission to encourage, empower, and educate others with and about alpha-gal
  • The AlphaGal Kitchen: A website dedicated to providing alpha-gal-safe recipes to the community
  • Alpha Gal Support: A Facebook group to discuss all things related to alpha-gal
  • Mosaic: Why are so many people getting a meat allergy?: An article that discusses the history behind this emerging tick-borne disease
  • Ticked Off Mast Cell: An organization devoted to compiling resources on mast cell activation syndrome (MCAS) and tick-borne diseases
  • ZeeMaps: Interested to know if alpha-gal is in your area? ZeeMaps tracks the growth of tick-borne disease around the world.

Final Thoughts

Often, articles on the subject of alpha-gal suggest that the syndrome may simply disappear in people after two to five years. However, Burton has a different take on the illness: “Some people think it just goes away on its own. But I try to refer to it as remission because it can come back, and when it does, it comes back with a fury,” she says. “Ultimately, I wish people would take tick prevention seriously. Don’t get bit. Don’t get sick.”

1. Alpha-gal syndrome. Mayo Clinic website.
2. Alpha-Gal and Red Meat Allergy. American Academy of Allergy, Asthma, & Immunology website.
3. Wilson JM, Schuyler AJ, Schroeder N, Platts-Mills TAE. Galactose-α-1,3-Galactose: Atypical Food Allergen or Model IgE Hypersensitivity? Current Allergy and Asthma Reports. 2017; 17(1): 8. doi: 10.1007/s11882-017-0672-7

Public Hearing Video on WI Lyme Bills 315 & 316

Scroll to 1:20 to hear the Representatives behind the bills, their purpose and intent

All the speakers were for the two bills presented
  • Speaker from UWM Center of Excellence of Vector Borne Diseases
  • Friends of WI State Parks
  • 2 Patients
  • I speak at 2:16:00

While the two bills presented deal specifically with education and prevention, other bills have been proposed. Those are the ones I have deep concerns about. To read about the bills go here:

Specifically –

  1. LRBs 1652 and 3362 – Establishes a sixteen-member Tick-Borne Disease Study Committee to create a report for the legislature on consensus-based recommendations for policy changes on awareness, prevention, surveillance, diagnosis, reporting, and treatment of Lyme Disease

Since everything about Lyme/MSIDS is steeped in controversy, this panel could be made up of those who do not recognize that Lyme can be persistent, and that it’s common for coinfection involvement necessitating numerous drugs for extended periods of time. A great example of this happening as we speak is in the federal Tick Borne Disease Working Group:  Excerpt:

Dr. Shapiro is much more than just a representative of the IDSA. In addition to financial conflicts of interest that should preclude him from serving on the Working Group, for years Dr. Shapiro has notoriously waged war on Lyme patients, their doctors, and advocacy groups. Putting him on the Working Group shows tremendous lack of respect for Lyme patients and their concerns. (More than 21,000 people have signed our petition to remove Shapiro from the TBDWG.

On top of this, Shapiro accuses chronically infected, suffering patients with medically unexplained symptoms (MUS) and urges the medical community to develop ways to prevent “healthcare-seeking behaviors” by parents who believed their children may have Lyme disease:  Dr. Brian Fallon, a Columbia University Irving Medical Center psychiatrist states that patients with chronic, unexplained symptoms had all been healthy—until they got Lyme disease. These patients suffered from chronic pain, fatigue and cognitive problems that had a debilitating effect on their lives. They all had been treated with antibiotics with partial response but then relapsed.





Animal Health & Nutrition Forum – “Pets & Parasites: Diseases Transmitted by Fleas and Ticks and Their Impact on Animal and Human Health”

“Pets and Parasites: Diseases transmitted by fleas and ticks and their impact on animal and human health” – An Animal Health and Nutrition Forum

Fleas and ticks are the most common ectoparasites (external parasites) of dogs and cats worldwide. In addition to just being a nuisance, fleas are responsible for flea allergy dermatitis and Bartonellosis while ticks are important vectors of diseases that affect humans and animals. The geographic distribution of ticks is changing due to climate change, de-foresting, and the changing living and migrating patterns of deer, birds, and rodents. Ticks are in virtually all parts of the United States, including some urban areas, and many parts of the world. Tick-transmitted diseases include: Lyme disease, Ehrlichiosis, Anaplasmosis, Rocky Mountain Spotted Fever, Babesiosis, and Hepatozoonosis.

Featured Speakers:

Dr. Edward B. Breitschwerdt
Edward B. Breitschwerdt,
Ph.D., NCSU College of
Veterinary Medicine
Dr. Kerrie Powell
Kerrie Powell, Ph.D.,




The AH&N EG forum will discuss Bartonellosis as well as outline the discovery and development of molecules that treat flea and tick infestations on companion animals.




4:30 p.m. – 5:00 p.m. Registration

5:00 p.m. – 6:00 p.m. Presentations

6:00 p.m. – 7:00 p.m. Networking & Refreshments


Parking is free


RSVP is required to reserve your seat.

  • NCBiotech
    15 TW Alexander Drive
    RTP, NC  27709
  • FREE

Public Hearing Tomorrow (Aug. 15, 2019) Two WI Bills on Tick Prevention

I apologize for this late notice.  I just received it myself. I was told the two Lyme bills would be presented around noon.


PUBLIC HEARING Committee on Environment

The committee will hold a public hearing on the following items at the time specified below:

Thursday, August 15, 2019 11:00 AM
412 East

Assembly Bill 190

Relating to: wetland mitigation banks, providing an exemption from emergency rule procedures, providing an exemption from rule-making procedures, and requiring the exercise of rule-making authority.

By Representatives Tusler, Ohnstad, Sinicki, Kerkman and Mursau; cosponsored by Senators Wanggaard, Cowles, Wirch and Olsen.

Assembly Bill 210

Relating to: time limits for correcting violations found by the environmental compliance audit program.

By Representatives Brooks, Brandtjen, Knodl, Kulp, Skowronski, Tusler and Wichgers; cosponsored by Senators Jacque, Cowles and Miller.

Assembly Bill 297

Relating to: changes to the electronic waste recycling program and granting rule- making authority.

By Representatives Mursau, Hebl, Anderson, Ballweg, Billings, Ohnstad, Shankland, Sinicki, Skowronski, Spreitzer, Stubbs, Tusler, Vruwink, Spiros and Subeck; cosponsored by Senators Miller, Cowles, Larson, Smith, L. Taylor, Wirch and Carpenter.

Assembly Bill 315

Relating to: signs informing about Lyme disease in state parks, state trails, state recreational areas, and state forests and making an appropriation.

By Representatives Mursau, Milroy, Anderson, Considine, Crowley, Edming, Emerson, Gruszynski, Hesselbein, Kulp, B. Meyers, Ohnstad, Ott, Pope, Ramthun, Rodriguez, Sargent, Shankland, Sinicki, Snyder, Spiros, Spreitzer, Tauchen, C. Taylor, Thiesfeldt, Tusler and Rohrkaste; cosponsored by Senators Cowles, Miller, Carpenter, Hansen, Larson, Olsen, Petrowski, Ringhand and Smith.

Assembly Bill 316

Relating to: making insect repellant available for sale in state parks and state forests.

By Representatives Mursau, Milroy, Anderson, Crowley, Edming, Emerson, Gruszynski, Hesselbein, Kulp, B. Meyers, Ohnstad, Ott, Pope, Ramthun, Shankland, Sinicki, Snyder, Spiros, Spreitzer, Tauchen, C. Taylor, Thiesfeldt, Tusler and Rohrkaste; cosponsored by Senators Cowles, Miller, Carpenter, Hansen, Larson, Olsen, Petrowski, Ringhand and Smith.

Representative Joel Kitchens Chair


For more on the bills:

News story on bills:


What Tick Saliva Does to the Human Body

A castor bean tick under a scanning electron microscope
Hard ticks inject saliva that suppresses the host immune systemJANA BULANTOVÁ / CREATIVE COMMONS

José Ribeiro was 33 when he got his first tick bite, in the 1980s, and he remembers it as a momentous occasion. He had recently started studying tick saliva, a complex molecular cocktail that ticks inject into their hosts to inhibit pain, prevent blood clotting, and suppress the immune system—all so the tick can feed undetected for days and days and days. Ribeiro had been studying this in a lab, but now he was finally witnessing it in the flesh. In his flesh.

He marveled at the bite. It did not hurt. It did not itch. “I was amazed at how they could be so stealthy,” recalls Ribeiro, who now studies disease-carrying insects and ticks at the National Institute of Allergy and Infectious Diseases. Ticks use saliva to manipulate the body of their hosts so their bites stay painless, itchless, and as unobtrusive as a bug swelling with blood can be. Scientists have since cataloged more than 3,500 proteins from the saliva of various tick species.

Ticks evolved this molecular cocktail because they, unlike virtually any other blood feeder, feed for days at a time on a single host. Most tick species feed only once during each stage of their life cycle (larva, nymph, adult), so they have to get a “voluminous blood meal” out of each host, says Sarah Bonnet, who studies ticks at the French National Institute for Agricultural Research. A tick might even wait years between feedings. In the meantime, it must subsist entirely on its previous blood meal. Each meal counts for a lot.

When a tick starts to feed, it doesn’t suck blood out of blood vessels. Instead, it secretes enzymes in its saliva that destroy a small ring of host tissue. This creates a “feeding cavity,” which Ribeiro likens to a “lake of blood.” “The tick sucks blood from that lake,” he says. For this strategy to work though, ticks also need to make proteins that prevent blood from clotting, as it normally wants to do in an injury site. Over the course of days, a host’s body will try to heal the wound by sending cells that make collagen. Normally, this would allow the wound to scar over, but tick saliva has molecules to counteract this, too.

Lastly, the tick has to evade a host’s immune system. Mammals, including humans, have complex immune systems with multiple lines of defense, and tick saliva can neutralize pretty much all of them. To start, ticks secrete molecular “mops,” which bind to and neutralize histamine. Histamine is best known for causing itching and redness, but it also plays an important role in opening up blood vessels to allow immune cells to get to a site of injury. Tick saliva prevents this, so tick bites don’t itch and immune cells can’t get to the bite. Tick saliva also degrades pain-inducing molecular signals in a host. That’s why tick bites also do not hurt. Ticks then inject molecules that neutralize or evade a suite of white blood cells that would otherwise be eating or attacking an invader.

The exact cocktail of a tick’s saliva proteins changes every few hours, Ribeiro says. The thousands of proteins in its saliva are highly redundant in function, and the tick cycles through them as a way of circumventing a host’s immune system. Immune systems take time to recognize and react to a foreign tick protein, and this strategy simply doesn’t give a host’s cells a chance to do that. Suppose, Ribeiro says, “Monday a tick starts feeding on you and injecting the saliva in you.” By Friday, when your body can mount a proper immune response against those first proteins, “the tick has already changed the repertoire.”

Ticks, of course, are noteworthy not just because they bite, but because they transmit diseases when they bite—including Lyme disease, babesiosis, Rocky Mountain spotted fever, and many, many others. And pathogens may take advantage of the fact that tick saliva suppresses a host’s immune system. Bonnet has found that ticks carrying the bacteria for cat-scratch disease (which, despite the name, is also transmitted by ticks) make more of a saliva protein called IrSPI. In a recent preprint, which has not yet been peer-reviewed, her team isolated IrSPI and found that it suppresses multiple types of white blood cells, weakening a host’s defenses at the bite. The upshot is that ticks can feed undetected, and bacteria can spread into a new host undetected. Tick saliva seems to help not just ticks, but the bacteria that live inside them.

But Bonnet thinks IrSPI could also be turned into a weakness. It could be a target for vaccines. If people are inoculated against IrSPI, their bodies might immediately recognize a tick bite and mount an immune response, preventing the tick from working its saliva tricks. (That’s why people who are bitten repeatedly will sometimes find the bites starting to itch.) Scientists are also interested in components of tick saliva that could be useful in cases where doctors want to inhibit pain or prevent blood from clotting. Ribeiro notes that this could be challenging because the proteins in tick saliva tend to be large and complicated—in other words, difficult to mass produce. But molecules from tick saliva are already being used to study certain unknown pathways in the human immune system. For example, scientists have used tick saliva to study how HIV infects cells.

Using tick saliva to study the human immune system makes a kind of sense. Over millions of years of evolution, ticks have essentially reverse engineered their hosts’ immune systems to evade them.


For more: