Summer is here and many of us are spending more time in the great outdoors. We know the importance of wearing insect repellant not only to protect us from annoying bug bites but more importantly, from contracting diseases that are carried by mosquitoes, lice, fleas, and ticks. We worry about viruses (i.e. yellow fever), bacteria (i.e. Lyme disease), and parasites (i.e. malaria), but do you know that a tick bite can also cause an allergy to meat?
Alpha-gal syndrome is a type of food allergy to red meat. In the U.S., this immunoglobulin E (IgE)-mediated allergic reaction is triggered from the bite of a Lone Star tick (Amblyomma americanum)
that transmits a carbohydrate molecule called galactose-alpha-1,2-galactose (alpha-gal) into the body. Alpha-gal is found on cells and tissues of all mammals except primate mammals (i.e. humans, chimpanzees, and monkeys) (Commins, 2019). Ticks that cause alpha-gal syndrome pick up the molecule from the blood of animals that they bite. When the tick bites a human, alpha-gal is transferred into the person’s body. Several tick bites may result in an immune system sensitivity to red meat that could progress from a mild reaction to severe and/or life-threatening anaphylaxis.
The Lone Star tick is found mainly in the southeastern U.S. however it has spread to northern and western parts of the country. Alpha-gal syndrome has also been reported in Australia, Spain, Germany, Japan, and Sweden and may be caused by other types of ticks such as Ixodes ricinus, Ixodes holocyclus, Amblyomma cajennense, Amblyomma sculptum, and Haemaphysalis longicornis
Symptoms (Mayo Clinic, 2019; Strickler, 2017)
Signs of an allergic reaction may appear two to ten hours after eating red meat, unlike other food allergy reactions which often occur within minutes of ingestion. Symptoms include:
- Hives, pruritus, scaly skin
- Swelling of lips, face, tongue, throat
- Lightheadedness, hypotension, syncope
- Shortness of breath
- Runny nose, sneezing
- Abdominal pain, diarrhea, nausea, vomiting
Prevention [Centers for Disease Control and Prevention (CDC), 2018]
The best way to prevent alpha-gal syndrome is to protect yourself from tick bites.
- Cover exposed skin: wear shoes, long pants, long-sleeved shirts, hat and gloves.
- Stay on trails and avoid walking through bushes and long grass.
- Use insect repellent when in grassy and forested areas.
- Use repellant containing DEET, picaridin, IR3535, Oil of Lemon Eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone.
- Apply repellent to children, avoiding hands, eyes and mouth.
- Do not use repellant on babies younger than 2 months old.
- Do not use products containing OLE or PMD on children under 3 years old.
- Apply 0.5% permethrin to boots, clothing, camping gear or wear pre-treated clothing.
- Perform a tick check after spending time outside.
- Carefully check pets, coats and backpacks
- Perform a full body check: under arms, in/around ears, behind knees, hair/scalp/neck, between the legs and around the waist.
- Shower to remove ticks that have not attached to the skin.
- Wash clothes in hot water and dry clothing in dryer on high heat for 10 minutes to kill ticks.
- For ticks that have attached to the skin (CDC, 2019):
- Using tweezers, grab the tick as close to the skin as possible.
- Pull up gently with steady pressure, careful not to squeeze or crush the tick.
- After removal clean the skin and hands with rubbing alcohol or soap and water.
- Discard the tick by either placing it in alcohol, a sealed container, or flushing it down the toilet.
Nursing Considerations (Strickler, 2017)
- Alpha-gal syndrome is typically diagnosed through personal history in addition to a blood test to assess for alpha-gal antibodies in the blood.
- Beef is the most common red meat to cause this allergic reaction, however alpha-gal may be caused by gelatin, milk and some cheeses.
- Red meat should be avoided in all forms including soup stocks, gravy packages, meat extracts and flavoring.
- Patients should carry an epinephrine autoinjector (i.e. EpiPen, Auvi-Q) for severe allergic reactions.
- Typical emergency treatment for anaphylaxis includes epinephrine, histamine blocker, and corticosteroids.
- Inform your patients that they may have an allergic reaction to products that contain gelatin such as those found in I.V. colloid solutions, vaccines, capsules, and suppositories (Stewart et al., 2015).
- Porcine heart valve replacement may cause a life-threatening allergic reaction (van Nunen, 2015)
Center for Disease Control and Prevention (2019). Tick removal and testing. Retrieved from https://www.cdc.gov/lyme/removal/index.html
Center for Disease Control and Prevention (2018). Preventing tick bites on people. Retrieved from https://www.cdc.gov/lyme/prev/on_people.html
Commins, S.P. (2019). Allergy to meats. Retrieved from https://www.uptodate.com/contents/allergy-to-meats?search=lone%20star%20tick
Mayo Clinic (2019). Alpha-gal syndrome. Retrieved from https://www.mayoclinic.org/diseases-conditions/alpha-gal-syndrome/symptoms-causes/syc-20428608.
Stewart, P.H., McMullan, K.L. & LeBlanc, S.B. (2015). Delayed red meat allergy: clinical ramifications of glactose- α-1,3-galactose sensitization. Annals of Allergy, Allergy & Immunology, 115(4), 260-264. DOI:10.1016/j.anai.2015.08.003
Strickler, J. (2017). Mammalian meat allergy: Unexpected danger. Nursing2017, 47(8), 47-51. DOI:10.1097/01.NURSE.0000521027.38133.7d
Van Nunen. (2015). Tick-induced allergies: mammalian meat allergy, tick anaphylaxis and their significance. Asian Pacific Journal of Allergy and Immunology, 5(1), 3-16. DOI:10.5415/apallergy.2015.5.1.3