Pia Untalan Olafson, Research Molecular Biologist, USDA-Agricultural Research Service
In recent news, individuals in certain parts of the United States have exhibited a delayed allergic response to red meat, and the allergy is reportedly associated with being bitten by the Lone Star tick. If you are concerned, and would like to know more about the tick-meat allergy relationship, you can find the answers to commonly asked questions below.
Can you explain the mammalian meat allergy we’ve been hearing about in the news?
Patients experiencing this allergy report intense itching, swelling, and/or develop hives at 3 – 6 hours after eating red meat. It’s this delayed reaction that is an important characteristic of this allergy. Scientists have identified that a sugar modification on red meat causes a heightened immune response in these patients. The sugar modification is called alpha-gal1, and it is found on meat and meat products from beef, pork, lamb, venison and rabbit.
Can a tick bite really cause humans to develop this allergy to red meat?
It is possible. It may sound like something straight out of the Twilight Zone, but in the United States there is a strong association between having the mammalian meat allergy and experiencing a history of bites from the Lone Star tick.
How does the Lone Star tick change the way the human immune system reacts to alpha-gal1?
That’s a great question. Eating meat and meat products alone does not prime the immune system. Rather, scientists believe something is transmitted to the human host during tick feeding that stimulates the production of host antibodies that specifically recognize alpha-gal. After this event, exposure to alpha-gal by eating meat or meat products triggers the host immune system and results in the observed allergy.
Approximate distribution of the Lone Star tick. Source:CDC
When ticks attach to their host, in this case a human, they secrete saliva into the host. Tick saliva contains biomoleculesthat enable the tick to evade the host’s immune system and successfully take a bloodmeal. While we know tick attachment and feeding are important routes of introduction, it still remains unknown what exactly the tick is transmitting that would prime the human immune system to recognize the alpha-gal on meat and meat products.
How severe is the reaction?
The allergic response varies – it can be minor, but it can also be severe enough in cases to warrant emergency room visits and/or hospitalization.
Who does this food allergy affect?
This food allergy affects both children and adults; however, not everyone who is bitten by the Lone Star Tick develops the food allergy. A significant proportion of those affected report a repeated history of tick bites. The meat allergy can also occur in individuals who have previously consumed red meat without problems, also known as adult onset.
Will I ever be able to eat red meat again?
Scientists have begun to uncover that the response to alpha-gal1 can wane over time; however, additional tick bites in the interim can boost the immune response. According to Dr. Scott Commins, a renowned scientist working with mammalian meat allergy patients, “It’s certainly something that does not appear to be a forever diagnosis2.”
How do I know I if have been bitten by the Lone Star tick?
The Lone Star tick is distributed throughout the eastern and southeastern United States. Adult female Lone Star ticks are easily recognizable because of the white spot on their backs, and these females will attach and feed until they engorge, if not removed. Larval ticks are much smaller and most times aren’t noticed until itching begins and welts start to form on areas where the larvae have attached. The TickEncounter Resource Center provides a chart to assist with identification of ticksfrom various geographic regions. If you’re unable to identify an adult tick that is attached to you, images of the tick can be submitted for identification to TickSpotters, part of the TickEncounter Resource Center. Larval ticks can be collected from individuals using masking tape or a lint roller. The tape of larval ticks can then be placed in a resealable plastic bag and provided to your State Entomologist for identification.
The Lone Star tick is recognizable because of the white dot on its back. Source: CDC
Is there a way to test if I am producing antibodies to alpha-gal?
Physicians and allergists are becoming more aware of the tick-induced delayed allergy to red meat, and a laboratory diagnostic test is available to screen patients for the presence of the antibodies that react to alpha-gal1. An allergist can order the test and provide the results.
Is there a time during the year when Lone Star Ticks are more prevalent?
The different lifestages of the Lone Star tick (larval , nymphal and adult) exhibit seasonal patterns of activity that vary widely by geography and climate. In general, adults peak in spring/early summer (March-July), the nymphs in April-September, and the larvae in June until the first hard frost.
How can I reduce my probability of acquiring the tick-induced mammalian meat allergy?
Warmer temperatures and longer days signal the start to spring and summer outdoor activities like hiking, biking and gardening. While the time spent outdoors is refreshing after the winter months, it also increases the chance of exposure to disease-transmitting insects and ticks, including the Lone Star tick. Tick bite prevention is an essential component to reducing prevalence of the mammalian meat allergy. The Centers for Disease Control recommends measures such as wearing hats, long sleeves, pants and closed-toe shoes when visiting areas likely to be tick-infested, such as brush land or wooded areas. Also suggested are application of repellents containing 20 – 30 {62211894bbe3543ea27fa51e74e3ab79f2baeee0f4cbac9ff4b15b5bf1d81fd0} DEET to exposed skin and clothing, as instructed on the product label, and treatment of clothing and gear with products containing 0.5{62211894bbe3543ea27fa51e74e3ab79f2baeee0f4cbac9ff4b15b5bf1d81fd0} permethrin. Be sure to conduct a full-body tick check after working in tick-infested areas in order to locate and properly remove attached adult ticks.
[1] galactose-alpha-1-,3-galactose
2 JAllergyClinImmunol, JACI Interview with Dr. Scott Sicherer and Dr. Scott Commins. Retrieved from https://youtu.be/NIvGYJ_DidA, July 14, 2014
For more information about the Lone Star tick, visit the Centers for Disease Control website.
or visit the National Alliance of Safe Pest Control at http://www.pests.org
Source: Facts About Beef
