Researchers: Invasive fire ants may limit spread of meat allergy caused by tick bite
August 1, 2020
Researchers say invasive fire ants could be limiting the spread of a dangerous meat allergy, but the ants themselves can also cause severe allergic reactions.
According to a release, the researchers at the University of Virginia School of Medicine were looking into the scope of the “alpha-gal” meat allergy in the United States, which is spread by the bite of the lone star tick.
People who are bitten by this tick may develop a potentially severe allergic reaction to mammalian meat, such as beef or pork.
The release says this allergy is commonly seen throughout the Southeast, the Mid-Atlantic and the Midwest, but it is not seen very often along the Gulf Coast or in Texas.
The researchers determined that this is likely caused by the steady expansion of fire ants that were accidentally imported from South America in the 1930s.
However, in some cases, these ants can cause life-threatening anaphylaxis, a severe allergic reaction, with their bite as well as posing dangers to animals and crops.
The release says these invasive ants are marching northward.
“We did not set out to study fire ants, but when the number of alpha-gal cases in the Gulf Coast was consistently lower than we expected, the fire ant emerged as an interesting explanation,” said researcher Behnam Keshavarz, PhD.
The alpha-gal meat allergy was identified more than a decade ago by UVA’s Thomas Platts-Mills, MD, PhD.
Since then researchers have looked into how the tick bite causes the allergy to develop, causing the body to react to a sugar, called alpha-gal, that is present in meat and other mammalian products.
Symptoms of this allergy include itchy rashes, nausea, and difficulty breathing. Severe reactions can progress to anaphylaxis if it is not treated.
The researchers aimed to look into the geographic scope of the allergy by surveying allergists across the country to map out cases of the alpha-gal allergy.
They also tested blood samples from two geographic areas where the allergy is frequently seen. These tests helped show the allergy is “immunologically similar” across the United States.
It was found to be common in large parts of at least 14 states, including 11 where at least one allergist reported more than 100 cases in their practice. These states are Alabama, Arkansas, George, Kentucky, Maryland, Missouri, New York, North Carolina, Oklahoma, Tennessee, and Virginia.
Comparatively, six of ten allergy practices in eastern Texas, which is where the invasive fire ant is located, saw no cases of the meat allergy.
The researchers considered potential explanations for why these areas saw no cases of the reaction. So they then asked the same allergists about reactions caused by the fire ant.
When they overlaid their results, they found an inverse relationship showing that the areas with the most fire ant cases had the lowest presence of the meat allergy.
The release says this suggests fire ants may be preying on the ticks or competing with them, thus limiting the spread of the meat allergy.
The researchers also found an increasing number of allergy cases caused by the fire ants, which will likely continue as the fire ants spread farther north.
The spread of the ants may help control the number of meat allergy cases that occur in the Southeast and Mid-Atlantic, but it will also likely lead to an increase in allergic reactions to the fire ants.
“These are two arthropod-related allergic diseases that are connected with each other,” said Platts-Mills. “The situation is unique because we think we can predict how both will change over time.
The release also highlights an unexpectedly high number of cases in part of northern Minnesota where the lone star tick is not known to be a common pest.
In that part of the state, three separate providers reported at least five cases of the meat allergy, and one had more than 40.
Researchers suggest this may mean that another tick species or other parasite is capable of spreading the allergy. There are other tick species outside of North American that do.
“The best evidence is that lone stars are the dominant cause of the alpha-gal meat allergy in North America,” said Jeffrey Wilson, MD. PhD. “That said, we wouldn’t be surprised if other ticks, chiggers or even other kinds of parasitic organisms can occasionally contribute to allergic sensitization to alpha-gal.”
These findings have been published in the Journal of Allergy and Clinical Immunology.
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