Key points
- Alpha-gal syndrome (AGS) is diagnosed through a detailed patient history, physical examination, and a blood test.
- Allergy skin testing may also be used to diagnose AGS.
- AGS is not a nationally notifiable condition, but CDC encourages jurisdictions to report cases of AGS.
Recommended tests
The main diagnostic test for AGS is a blood test looking for immunoglobulin-E antibodies specific to alpha-gal (alpha-gal sIgE). The LOINC Code is 73837-7 Galactose-alpha-1,3-galactose (Alpha-Gal) IgE Ab [Units/volume] in Serum.
Tests for alpha-gal sIgE antibodies are available at several large commercial laboratories.
Tests also may be available at some academic institutions.
Skin tests for reactions to allergens like pork or beef may also be used to diagnose AGS.
Diagnosis
AGS is diagnosed through
- A detailed patient history
- Physical examination
- A blood test
The blood test looks for specific IgE antibodies the immune system produces in response to alpha-gal. However, a positive alpha-gal sIgE test does not mean a person has AGS.
Positive alpha-gal specific IgE tests may occur in people who do not have AGS, particularly in regions with lone star ticks.
Providers should consider the tests along with
- Symptoms
- Whether allergic reactions are delayed
- History of recent tick bites or outdoor exposure
Allergy skin testing may also be used to help diagnose AGS.
Reporting cases
AGS is not a nationally notifiable condition, however, your state may require reporting. Check with your state and local health departments about reportable diseases. All jurisdictions are encouraged to report cases of AGS with members of CDC's Rickettsial Zoonoses Branch to inform better understanding of national trends.
Case report form
Submit case report forms to rzbepidiag@cdc.gov or fax it to 1-404-471-2737.
Case definition
The Council of State and Territorial Epidemiologists (CSTE) approved a position statement standardizing a case definition for alpha-gal syndrome (AGS) in 2021. The case definition is for surveillance purposes only and does not replace a clinical diagnosis by a healthcare provider.
A standard surveillance case definition provides consistent laboratory and clinical criteria to ensure that data captured across multiple jurisdictions are comparable.