Study Finds Nearly 1 in 4 Adults Test Positive for Alpha-Gal Antibodies in Five High-Risk States

A CDC-led study of 3,000 blood samples reveals that nearly 24% of adults in Arkansas, Missouri, Virginia, Kentucky, and Tennessee test positive for alpha-gal antibodies, which are linked to red meat allergies triggered by lone star tick bites. Arkansas has the highest rate at 31.2%. Because positive tests far exceed actual allergy cases, officials warn against testing asymptomatic patients to avoid overdiagnosis.

Alpha-gal antibody seroprevalence study

• ▪A study conducted from November 2024 to April 2025 tested 3,000 blood donor samples across 10 states to evaluate alpha-gal antibody prevalence
• ▪The Centers for Disease Control and Prevention led a study showing that nearly one in four adults in five high-risk states test positive for alpha-gal antibodies

Lone star tick transmission mechanism

• ▪Alpha-gal is a sugar molecule found in most mammals but not in humans, and it is transferred to humans through lone star tick bites
• ▪When a lone star tick transfers alpha-gal to a human, the body produces alpha-gal-specific immunoglobulin E antibodies, which can trigger severe allergic reactions to red meat

State-level geographic prevalence patterns

• ▪Arkansas had the highest estimated alpha-gal antibody seroprevalence at 31.2%, followed by Missouri at 26.0%, with Virginia, Kentucky, and Tennessee all above 21%
• ▪Alpha-gal antibody prevalence was much lower in New Mexico at 1.9% and Washington state at 1.1%, both of which have no known lone star tick populations

Age, sex, demographic variations

• ▪Alpha-gal antibody seroprevalence was 60% lower among people aged 16 to 34 years old than among adults aged 55 to 64
• ▪Alpha-gal antibody seroprevalence was higher among men than women, and lower among Hispanic people than non-Hispanic people

Testing guidance for clinical diagnosis

• ▪Relying solely on positive alpha-gal IgE test results without clinical symptoms of alpha-gal syndrome can lead to overdiagnosis and unnecessary dietary restrictions
• ▪The Centers for Disease Control and Prevention recommends that healthcare providers only test patients for alpha-gal antibodies if they exhibit clinically compatible symptoms

Population density inverse correlation

• ▪For every tenfold increase in county population density, the probability of a resident testing positive for alpha-gal IgE antibodies decreased by 29.5%
• ▪County population density was inversely associated with alpha-gal antibody seropositivity, indicating higher prevalence in less densely populated rural areas