SOUTH CAROLINA — A study published in Morbidity and Mortality Weekly Report found that up to 30 percent of people in some parts of the U.S. carry the antibody associated with alpha-gal syndrome. Researchers led by infectious disease experts at the University of North Carolina at Chapel Hill collected samples from 3,000 blood donations across 10 states.

The study included 300 samples per state from Arkansas, Kentucky, Missouri, South Carolina, Tennessee, Virginia, New Mexico, Washington, Minnesota, and Maine. Arkansas had the highest estimated alpha-gal antibody prevalence among the studied states, at 31.2 percent. Tennessee had an estimated alpha-gal antibody prevalence of 21.5 percent. South Carolina had the lowest estimated prevalence of alpha-gal antibodies among the six states in lone star tick territory, at 5.5 percent.

Maine had an estimated alpha-gal antibody prevalence of 10.6 percent. Minnesota had an estimated alpha-gal antibody prevalence of 5.4 percent. New Mexico had an estimated alpha-gal antibody prevalence of 1.9 percent. Washington had an estimated alpha-gal antibody prevalence of 1.1 percent. The five states with the highest prevalence had a collective estimated prevalence of 24 percent.

Alpha-gal syndrome is an allergic response triggered by IgE antibodies that attack a double-sugar molecule called galactose-α-1,3-galactose, also known as alpha-gal. The alpha-gal molecule is found in the cells of nonprimate mammals, including cows and pigs, and is released in the saliva of ticks, particularly the lone star tick. Symptoms of alpha-gal syndrome can include hives, nausea, vomiting, abdominal cramps, diarrhea, and anaphylaxis.

The Centers for Disease Control and Prevention previously estimated that 0.14 percent of the U.S. population, or up to 450,000 people, has alpha-gal syndrome. Alpha-gal syndrome was first described in the early 2000s. In 2007, researchers reported that many cancer patients in Tennessee and North Carolina had severe allergic reactions to the drug cetuximab, which contains alpha-gal. The study researchers did not have data on whether the blood donors had been diagnosed with alpha-gal syndrome. Clinical guidelines recommend that people suspected of alpha-gal syndrome avoid meat for a trial period to see if symptoms improve before receiving a diagnosis. Some small studies have linked alpha-gal IgE antibodies to higher risks of coronary artery disease.