Lone Star Tick

Common Name: Lone Star tick, Turkey tick– The prominent single white spot that marks the center of the carapace of females gave rise to the “lone star” metaphor. Although the tick is found in Texas, there is no evidence that it got its name from the state.

Scientific Name: Amblyomma americanum – Ambly is a combining form directly from Greek that means blunt or obtuse. Omma is similarly derived meaning eye.  The genus was originally named by Carolinus Linnaeas in 1758 with the lone star tick as its type species. It is probable that “blunt eye” was due to the presence of the white dot. The species name is from its origination in the North America.

Potpourri: Up until about ten years ago, the lone star tick was dismissed as an interesting but esoteric member of Ixodidae, the tick family. It is not even included in popular field guides. [1] It was overshadowed by the black-legged tick, a cynosure due to the prevalence of Lyme Disease as a human pathogen. The wood tick, almost identical to the lone star tick lacking only the white dot, is much more common in the mid-Atlantic region. That all changed when people reported having a severe allergic reaction after eating red meat. This inexplicable and widespread medical issue that often led to hospital emergency rooms drove a quest for causation. Epidemiological research that spanned a decade eventually correlated times and locations of the severe and tellingly delayed anaphylactic shock of the red meat allergy to having been bitten by the lone star tick. Its spread eastward and northward over time has led to continued study and research as a public health issue.  

The lone star story (not the one about the Alamo) started as an attempt to find the root cause of a disturbing sequence of unusual and serious medical anomalies. This is not unlike most complex interactions between human health and nature exemplified by the English physician John Snow, who traced the cause of cholera to the contaminated Broad Street water pump in London in 1854 and true also for Lyme Disease. The first recorded correlation between lone star ticks and allergic reactions due to the consumption of mammalian meat occurred in Athens, Georgia in 1989. Dr. Antony Deutsch and Mrs. Sandra Latimer noted that there had been ten cases in which delayed anaphylaxis and/or hives occurred in patients who consumed red meat and who also been bitten by ticks some months before.  Blood tests revealed that all of those affected had elevated blood levels of Immunoglobin E (IgE), a naturally occurring antibody that is an integral part of the immune system of all mammals that had supposedly been stimulated by something contained in red meat. Although reported to the Centers for Disease Control (CDC) in 1991, there was no follow-up. [2]

Fifteen years later, a University of Virginia allergy researcher named Thomas Platts-Mills was trying to understand why some cancer patients had experienced severe allergic reactions when given the drug cetuximab. The key to the puzzle was a chemical named with the tongue twisting lexicon of organic chemistry galactose-alpha-1,3-galactose. This is a type of sugar in red meat (including pork, “the other white meat”) which was also one of the ingredients found in the cancer drug cetuximab. While the nickname alpha-gal seems to have been an innocuous shorthand version of the longer name, it does offer some speculation about its origination. The similarity to the sexist archetype alpha-male of boardroom and bedroom notoriety can hardly be ignored. That it is a component of red meat, the consummate breakfast of champions borders on sardonic, alpha-gal for alpha-male.  The final piece of the puzzle was geographic. Those cancer patients who experienced anaphylaxis when given cetuximab were from the so-called tick belt of the southeastern states, some with “massive tick bites on their ankles.” Dr. Platts-Mills confirmed his hypothesis a year later when he went on a hiking trip in the Appalachian Mountains near UVA in 2007. He returned to discover his ankles covered with lone star larva and a self-administered blood test confirmed high IgE levels. After a lamb dinner several months later, he awoke in the middle of the night covered with hives. [3]

In the succeeding fifteen years that brings us to the present, the correlation between lone star tick bites and red meat allergy has been accepted beyond correlation to causation. A report issued by the Centers for Disease Control in 2023 found that there were 110,000 confirmed cases of what has come to be known as the alpha-gal syndrome (Electra complex was ruled out) in the United States between 2010 and 2022. The number was based on data from laboratory testing incident to patients seeking medical care for life-threatening respiratory distress. The CDC concluded that underreporting of the condition was likely and that there were approximately four cases for every one reported and analyzed. With an estimated 450,000 cases during the twelve-year period of evaluation, tick-red meat allergy is in the top ten of food allergies in the United States. The reasons for the dearth of reported cases are uncertainty of symptoms and lack of awareness. The anaphylactic reaction usually occurs two to six hours after a meaty meal and months after a tick bite and can vary in severity across populations. A survey of 1500 clinicians revealed that almost half had never heard of the condition, precluding a diagnosis altogether. That lone star ticks are spreading north, and east is reflected in the data. The two states with the highest reported red meat allergy cases were Virginia and New York, where Suffolk County, the eastern two thirds of Long Island, accounted for four percent of all cases nationwide. [4]

While much has been learned about the lone star tick to date, research continues. The first order of business is to determine the ultimate source of the chemical that induces the IgE autoimmune spike. There are three hypotheses. The first is that the IgE stimulant is contained in the lone-star tick’s saliva, which, like all ticks, is a complex chemical mix that contains anticoagulants to ensure blood flow from the host, anesthetics to dull the host’s senses so as to avoid detection, and immunosuppressive agents to blunt host rejection. The second is that mammal blood from a previous meal contained the IgE antigens, a not unreasonable hypothesis given its provenance. The third is that the lone star tick is a vector to transfer the inflicting agent from one host to another, similar to the transmission of Borrelia burgdorferi that causes Lyme Disease from the white footed mouse to humans by the black-legged tick. Based on the results of the investigations, some form of antidote could presumably be devised. At present there is no cure beyond avoiding future tick bites and hoping that the autoimmune response will abate over time. [5] However, the anxiety for a potential midnight ambulance ride to the emergency room after having hamburger helper for dinner causes most victims to avoid meat altogether, which is not necessarily a bad thing when health and the environment are taken into account. But for those who cannot imagine a life without pork chops and bacon, a company in Blacksburg, Virginia has developed an FDA approved genetically engineered pig that lacks the alpha-gal gene, called (what else?) Galsafe. While ostensibly to produce organs for use in humans that might otherwise be rejected, the company offers Galsafe meat to alpha-gal patients. [6]

A second line of research seeks to understand the cause or causes of the tick diaspora over the last several decades The spread of the lone-star tick outside its historical range is not unique, but a pattern now typical for most if not all ticks. One possibility would be the movement of the winter freeze line northward due to the now perceptible higher temperatures which opens new habitats for invertebrates like insects and ticks, the bark beetle’s devastation of western pine forests a case in point. However, ticks don’t fly, have miniscule legs, and can only crawl a short distance during their brief lives. The commonly accepted reason for the spread of ticks is the burgeoning numbers of white-tailed deer across the eastern half of North America, long a matter of public concern due to environmental damage and deadly vehicular collisions―and now lone star tick vectors to boot. Deer feeding habits take them through ideal tick habitats where they stand and graze placidly while the ticks gleefully jump on board for a meal. Deer provide ticks geographic mobility.  The lone star tick is also commonly found on wild turkeys. So much so that in the Midwestern states, they are called turkey ticks (just as the black-legged tick is called bear tick in northern states). [7] The upshot of more ticks is more tick-borne diseases, now more common and with more variety. Two additional diseases associated with the lone-star tick have become a matter of public health concern (over and above red meat allergy) over the last ten years.

Southern tick-associated rash illness (STARI) emerged from the fog of tick-borne disease data only gradually. Metabolic measurements of the blood from individuals with both Lyme Disease and with STARI revealed different biosignatures, confirming an alternative etiology. [8] The CDC recognizes STARI as a new disease but considers it to be of unknown origin, noting only that it is correlated with individuals bitten by lone-star ticks. The symptoms are the red circular rash, generally described as “bull’s eye” identical in appearance to that of the black-legged tick when Lyme Disease is contracted. [9] To complicate matters, a spirochete similar to that causing Lyme Disease, tentatively named Borrelia lonestari, has been found in at least one patient but does not seem to be routinely present in other victims; the search continues.

A second emerging disease attributed to lone star tick bites is Heartland virus, named for the Heartland Regional Medical Center in St. Joseph, Missouri, where the first two patients were treated in 2009. When seven additional cases including two fatalities occurred several years later, the quest for the source of the virus began in earnest. In 2013, 50,000 ticks were collected in Missouri and surrounding states and tested for Heartland virus. Only the lone-star ticks were found to have the virus. In parallel, between 2009 and 2014, blood samples from 1428 animals including white-tailed deer, raccoons, moose, and coyotes were analyzed to reveal that 103 tested positive. The tentative theory is that the lone star tick nymph has a blood meal on an infected animal, most likely deer, and then transmits it to a human as an adult. [10] And that is not all, the lone star tick has also been identified in the transmission of many of the known tick-borne diseases including ehrlichiosis, rickettsiosis, tularemia and protozoan infections. The spread of tick-borne diseases is a concern for anyone who spends time outdoors in grassy areas―like hikers.

A working knowledge of cradle to grave tick behavior helps establish actions needed to minimize the chances of getting bitten and contracting a tick-borne disease. Each lone-star tick hatches as a six-legged larva, one of about 5.000 eggs laid by a gravid female in a location chosen for likely success (females have been tracked moving over half a meter to find a suitable, moist location). The first of three blood meals is necessary to proceed to the eight-legged nymph stage (ticks are arachnids akin to spiders). The second blood meal provides the energy and nutrients to molt to an adult. Both larval and nymph stage ticks can survive up to six months without eating.  A last supper for both males to produce spermatophores and for females to produce eggs and pheromones to attract a mate completes the life cycle with oviposition. While larvae and nymphs parasitize birds and small mammals, adults literally quest for larger prey like deer and humans. [11] The evolution of ticks to survive on three mammal blood meals for the entirety of their short lives is one of the wonders of the natural world. Only three sensory capabilities exist to achieve this end. Photosensitivity draws the tick upward on a blade of grass until it is at or near the apex. Once in position, the tick extends its front legs to attach to a passing animal in a stance appropriately called questing. Ticks, the epitome of persistence, can remain ready at the quest for up to three years. A second sensitivity is butyric acid, an exudation of all mammals, necessary to consummate the quest on a suitable host. A third sensitivity is surface warmth, triggering proboscis insertion to initiate feeding. It doesn’t matter what is on the other side of the warm surface. A tick will suck from a balloon filled with warm water. [12]

So how can you protect yourself from tickborne disease? Three methods have been prescribed. The first line of defense is to use tick repellent like DEET. An acaracide (Acarina is the order for ticks and mites in the Class Arachnida) like permethrin that kills them is preferable. However, nothing is absolute, and ticks are insidious, penetrating the shield at an untreated spot inevitably missed during application.  The second line of defense is habitat removal, getting rid of the grasses that promote knee high access for successful attachment. Mowing may work around a farm, but it cannot be practical in open woods with passing trails. While it is good practice to hike in the middle of a trail where grass is beaten flat, a trip to the bushes will at some point be required. The third method is host removal. There have been studies that focus on the number of deer necessary to reduce tick populations which conclude that it would only work with near annihilation, neither feasible nor desirable. The one guaranteed method of preventing tick borne diseases is vigilance. A complete whole-body inspection down to bare flesh must be conducted after every hike in potential tick habitats between March and November, active tick season, If a tick is found and removed within 24 hours, the chances of protracting a disease are negligible. This is because it takes that long for the tick to drill the hole to reach blood and then to inject the chemical saliva that keeps the well open and flowing. The injected saliva carries disease pathogens. There will still likely be a maddingly itchy red spot to deal with, but topical creams and patience will suffice in remediation. However, an ambulance ride after a steak dinner can be averted.

References:

1. Milne, L. and Milne, M. National Audubon Society Field Guide to North American Insects and Spiders, Alfred A. Knopf, New York, 1980, pp. 423-430

2. Steinke, J. et al. “The alpha gal story: Lessons learned from connecting the dots”. The Journal of Allergy and Clinical Immunology. March 2015. Volume 135 Number 3, pp 589–597.

3. Beck, M. “Ticks that spread Red-Meat Allergy” The Wall Street Journal, 11 June 2013

4. Sun, L. “Tick-linked meat allergy may not be so rare, researchers say,” Washington Post, 28 July 2023. (The meat need not be rare either)

5. Steinke, op .cit.

6. Lewis, T. “Red Meat Allergy Caused by Tick Bite Is Spreading—And Nearly Half of Doctors Don’t Know about It” Scientific American, 7 August 2023.

7. University of Florida Entomology and Nematology Department https://entnemdept.ufl.edu/creatures/urban/medical/lone_star_tick.htm    

8. Molins, C. et al “Metabolic differentiation of early Lyme disease from southern tick–associated rash illness (STARI)” Science. 16 August 2017, Volume 9 Issue 403

9. https://www.cdc.gov/lyme/about/about-southern-tick-associated-rash-illness.html       

10. Enserink, M.” The Heartland virus may occur across eastern U. S.” Science 18 September 2015

11. University of Florida, op cit.

12. Wilson, N. “Acarina” Encyclopedia Brittanica, Macropedia Volume 1 pp 19-23 and Volume 2 p 805, William and Helen Benton Publishers, University of Chicago, Chicago Illinois, 1972.