Acute management involves administration of intramuscular epinephrine and circulatory support with intravenous (IV) crystalloids.
- Immediately assess the patient's airway, breathing, circulation, and mental status.
- Administer epinephrine 0.2-0.5 mg (in adults) or 0.01-0.3 mg/kg (in children) intramuscularly in a large muscle belly (eg, anterolateral thigh) every 5-10 minutes to manage symptoms.
- Support circulatory collapse with IV fluid resuscitation concurrent with epinephrine as above.
Tick bites from some Amblyomma (lone star tick) and Ixodes (and possibly Haemaphysalis) species have been associated with the subsequent development of immunoglobulin E (IgE) antibodies to alpha-gal (galactose-alpha-1,3-galactose), a mammalian oligosaccharide. Presence of IgE antibodies to alpha-gal is associated with 2 distinct forms of anaphylaxis in the United States, Europe, Asia, and Australia.
Individuals with elevated IgE titers to alpha-gal have experienced symptoms of urticaria, gastrointestinal distress, angioedema, and/or anaphylaxis immediately or 3-6 hours (delayed onset) after ingesting mammalian meat (eg, beef, pork) or being exposed to alpha-gal in products made from mammals (eg, medications, cosmetics, vaccines, gelatin, milk products). Implicated tick bites have been noted to be associated with pruritus for 2 or more weeks.
The other reaction seen in patients with IgE to alpha-gal is an immediate onset of anaphylaxis during first exposure to IV cetuximab, an epidermal growth factor receptor (EGFR) inhibitor used for the treatment of colorectal cancer, metastatic non-small cell lung cancer, and head and neck cancer.
A blood test for these IgE antibodies exists.
Delayed diagnosis and treatment of anaphylaxis of any cause predicts poor prognosis. Immediate management involves removal of the triggering allergen if possible, epinephrine by intramuscular injection, and further evaluation and management.
IgE to alpha-gal has been identified in some Sub-Saharan African populations where it is thought to be due to exposure to cestodes, nematodes, scabies, ticks, and a variety of other ectoparasites. Interestingly, however, there have been no reports of delayed anaphylaxis upon exposure to red meat in this population.
Per the US Centers for Disease Control and Prevention, the number of suspected alpha-gal syndrome cases in the United States has increased substantially since 2010, and states with established populations of lone star ticks are most affected (South, East, and Central United States), although suspected alpha-gal syndrome cases were also identified in areas outside of this tick's range.
