Alpha-Gal Syndrome: Spread & Awareness Timeline
In 2009, researchers at the University of Virginia described the first clinical cases of alpha-gal syndrome — a delayed allergic reaction to mammalian meat triggered by lone star tick bites. Sixteen years later, the CDC estimates that up to 450,000 Americans have been affected. This map traces that story year by year, showing how awareness has spread from a handful of southeastern states to a nationwide concern.
What this map shows
The state-level shading represents an alpha-gal awareness index — a composite measure derived from search interest data, published diagnosis rates, and surveillance reporting. Darker amber indicates states where alpha-gal syndrome is more widely recognized, tested for, and diagnosed. States with no shading have minimal documented AGS activity for that year.
Use the year slider or play button to animate the progression from 2010 to the present. The bar chart below the map shows the estimated number of new suspected cases per year — click any bar to jump to that year. Toggle the CDC tick surveillance overlay to see county-level lone star tick establishment data alongside the awareness layer.
The pattern of spread
Alpha-gal syndrome was first identified in Virginia, North Carolina, and Tennessee — states in the heart of lone star tick territory. As awareness grew among allergists and patients, diagnoses expanded through the mid-South and Southeast: Missouri, Arkansas, Kentucky, Georgia, and the Carolinas saw rapid increases in the early 2010s.
By 2017, when systematic lab surveillance began through Eurofins Viracor, AGS was being diagnosed in over 30 states. The pattern closely follows the expanding range of the lone star tick, which has been moving northward and westward due to warming winters and changes in deer populations. States like New York, New Jersey, Pennsylvania, and the upper Midwest began reporting cases as tick populations established in new areas.
The 2022 CDC report was a turning point for public awareness. Major media coverage brought alpha-gal syndrome to national attention, and search interest surged in states that had previously shown little awareness. By 2024, when AGS received its own ICD-10 diagnosis code, cases were being identified in nearly every state — though the Southeast remains the epicenter.
Why awareness matters as much as tick range
The map shows awareness, not just tick presence, because the two tell different stories. Many patients in low-awareness states go undiagnosed for years because local doctors have never encountered the condition. A state might have established lone star tick populations but low AGS diagnosis rates simply because clinicians are not testing for it.
This gap between where ticks are and where diagnoses happen is one of the biggest challenges in AGS. Toggle the tick surveillance layer to compare — you may notice states where tick establishment is documented but awareness remains low. Those are the areas where patients are most likely to be misdiagnosed or undiagnosed.
Data sources
- Case counts: CDC MMWR 2023 — Thompson et al., "Geographic Distribution of Suspected Alpha-Gal Syndrome Cases." Lab surveillance data from Eurofins Viracor (2017–2022) with earlier estimates from published literature.
- Awareness index: Derived from Google Trends relative search volume for alpha-gal related terms by state, cross-referenced with published state-level seroprevalence studies and media coverage timelines.
- Tick surveillance: CDC Lone Star Tick Surveillance Data — County-level Amblyomma americanum establishment status (2024).
- Growth trends: TriNetX electronic health record network analysis showing 5,520% increase in AGS diagnoses from 2015–2020 to 2021–2025 (PMC12365936). Fort Liberty seroprevalence study tracking sensitization rates from 1991–2019.