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Print this and take it to your appointment, or leave it at the practice. It is written for clinicians, not patients, and it is deliberately one page.
Alpha-gal syndrome
Tick-induced mammalian meat allergy. A summary for general practice.
AlphaGal Australia
TODO: URL
The diagnostic clue is the delay. Allergic symptoms beginning 2 to 10 hours after a meal containing mammalian meat, in a patient with tick exposure. The lag means neither patient nor clinician usually suspects food.
Presentation
- Urticaria, angioedema, pruritus (often palms and soles)
- Gastrointestinal symptoms: cramping pain, nausea, vomiting, diarrhoea. May be the only presentation and is frequently labelled IBS
- Anaphylaxis, including nocturnal presentations
- Severity varies between episodes. Cofactors such as alcohol, exercise, NSAIDs and intercurrent infection may lower the threshold
Consider it in
- Recurrent idiopathic anaphylaxis
- Chronic or recurrent urticaria of unclear cause
- Unexplained recurrent GI symptoms, particularly nocturnal
- Any of the above in a patient living in or visiting east coast tick habitat
Testing
- Alpha-gal specific IgE (serum) is the test. Order alongside a careful history
- Skin prick testing is unreliable for alpha-gal. A negative result does not exclude the diagnosis
- Sensitisation is not the same as clinical allergy. Asymptomatic seropositivity is common, so interpret against the history
- TODO: add MBS item number and rebate status
Management and referral
- Refer to a clinical immunologist or allergist for confirmation and risk assessment
- Provide an ASCIA Action Plan; prescribe an adrenaline autoinjector where indicated
- Advise avoidance of mammalian meat and mammal-derived products. Extent of avoidance is individual
- Counsel on tick bite prevention: further bites can increase titres and worsen reactions
- Flag the allergy in the record. Consider mammal-derived excipients, gelatine-containing products and relevant biologics
Australian context
The vector here is the Eastern paralysis tick (Ixodes holocyclus), distributed along the east coast from north Queensland through New South Wales into northern Victoria. The tick and mammalian meat allergy association was first described by van Nunen and colleagues in 2007. Case numbers have risen since 2020, with clustering on Sydney's Northern Beaches, the Sunshine Coast and Gold Coast hinterlands, the Northern Rivers and the Shoalhaven.TODO: insert verified CSIRO figures and citation
Note on tick removal: Australian guidance differs from much of the overseas material patients will encounter. Ticks should be killed in situ rather than grasped and pulled. TODO: reproduce current ASCIA wording verbatim here, with citation
Prepared by AlphaGal Australia as a patient-initiated summary. Not a clinical guideline. For authoritative guidance see ASCIA: allergy.org.au. Clinical reviewer: TODO. Last reviewed: TODO.