Geographic Distribution of Suspected Alpha-gal Syndrome Cases-United States, January 2017-December 2022

Alpha-gal syndrome (AGS) is an emerging, tick bite-associ-ated allergic condition characterized by a potentially life-threat-ening immunoglobulin E (IgE)-mediated hypersensitivity to galactose-alpha-1,3-galactose (alpha-gal), an oligosaccharide found in most nonprimate mammalian meat and products derived from these mammals. Specific symptoms and sever-ity of AGS vary among persons, and no treatment or cure is currently available. During 2010-2018, more than 34,000 suspected cases of AGS were identified in the United States, but current knowledge of where cases occur is limited. This study examined alpha-gal-specific IgE (sIgE) antibody testing results submitted to the commercial laboratory responsible for nearly all testing in the United States before 2022 to assess the geographic distribution and magnitude of this emerging condi-tion. During January 1, 2017-December 31, 2022, a total of 357,119 tests were submitted from residences in the United States, corresponding to 295,400 persons. Overall, 90,018 (30.5%) persons received a positive test result in the study period, and the number of persons with positive test results increased from 13,371 in 2017 to 18,885 in 2021. Among 233,521 persons for whom geographic data were available, suspected cases predominantly occurred in counties within the southern, midwestern, and mid-Atlantic U.S. Census Bureau regions. These data highlight the evolving emergence of AGS and can be used to help state and local health agencies initiate surveillance and target public health outreach and health care provider education to high-risk localities.

Automated summary

Alpha-gal syndrome is an emerging allergic condition associated with tick bites. It is characterized by a potentially life-threatening hypersensitivity to galactose-alpha-1,3-galactose (alpha-gal), which is found in nonprimate mammalian meat and products. The study found that suspected cases of AGS predominantly occurred in counties within the southern, midwestern, and mid-Atlantic regions of the United States. These findings highlight the need for surveillance and targeted public health outreach in high-risk areas.