Delayed Anaphylaxis, Hypotension Following Tick Bite
The allergy can be attributed to a bite from Amblyomma americanum, or the Lone Star tick.
A case report presented at the American Thoracic Society 2017 International Conference in Washington, DC, describes a patient who developed a serious, delayed allergic reaction to red meat that was triggered by tick bites.
The patient, a 65-year-old male from rural central Florida, presented to the clinic complaining of episodes of "spontaneous" anaphylaxis which had been occurring over the past 10 years. The episodes ranged in severity, sometimes requiring emergency department visits due to severe hypotension. The patient noted that over the years he had sustained multiple tick and mosquito bites as well as bee stings, but had no subsequent reactions from these bites. Lab results confirmed he had elevated serum immunoglobulin E (IgE) levels. Considering his history of tick bites, he was tested for alpha-gal allergy, which turned out to be positive. To prevent future episodes, the patient was advised to avoid mammalian meat products (ie, beef, pork, lamb, and milk).
An allergy to galactose alpha-1,3-galactose can cause a severe reaction in patients who ingest mammalian meat and milk products; these reactions are typically delayed, occurring 3-6 hours after consumption. States in the Midwest and South appear to have the highest prevalence of both alpha-gal allergy and rickettsial diseases transmitted by the Lone Star tick or Amblyomma americanum; individuals appear to be sensitized via tick saliva. Though Lone Star tick-associated disease is not currently prevalent in Florida, "the geographic distribution of this tick is expanding."
Not many things trigger delayed allergic reaction, so while initially the episodes seemed "spontaneous," an accurate diagnosis led the authors to identify the dietary trigger for this patient's allergy. "An accurate diagnosis led to significant diet modifications for this patient which may be life-saving," concluded the authors.
Robinson SW. Tick bites and delayed anaphylaxis to red meat: rare alpha-gal allergy in Florida. Presented at: American Thoracic Society 2017 International Conference; May 19-24, 2017; Washington, DC. Poster C36.