Case Presentation: A 82-year-old woman with a history of well-controlled asthma presented with shortness of breath. She developed acute onset shortness of breath while sitting at home thirty minutes prior to presentation, which was accompanied by nausea, vomiting, diarrhea and generalized urticaria. Upon presentation, her blood pressure was 86/71 mmHg, pulse rate was 86 /min, respiratory rate was 24 /min, and oxygen saturation was 98% on 4L of oxygen via nasal cannula. She was in moderate respiratory distress. Physical examination showed generalized maculopapular rash and bilateral wheezes on chest examination. Chest X-ray revealed clear lung field. She was diagnosed with anaphylaxis and treated with volume resuscitation, albuterol inhaler, intravenous steroid and histamine blockers. Her blood pressure normalized and patient’s symptoms resolved over the next several hours. The patient had no prior anaphylaxis episode and denied any intake of unusual food or medication. The trigger of anaphylaxis was not identified at that point. On the floor, the patient noticed a tick on her abdomen. The tick was removed and later identified as Amblyomma Americanum. Upon further questioning, the patient admitted that she went golfing one day prior to presentation and that she consumed beef four hours prior to the onset of her symptoms. The anaphylaxis was thought to be a delayed allergic reaction to red meat induced by the tick bite.
Discussion: The present case illustrated a unique cause of delayed allergic reaction induced by Amblyomma Americanum. The bite of this tick can cause a person to develop an allergy to nonprimate mammalian meat. This allergic reaction is characterized by a delayed reaction of urticaria or anaphylaxis developing four to eight hours after a consumption of the allergen. The allergen has been identified as a carbohydrate called galactose-α-1,3-galactose. The first case of this unique allergic reaction induced by a tick bite was reported in 2009. Since then, the awareness of this unique allergic reaction has been increasing. Amblyomma Americanum reportedly has been expanding its distribution to north and west out of the historic range and now is widely distributed across the eastern, southeastern and midwestern United States. Establishing the etiology of anaphylaxis is pivotal to long-term risk management. In anaphylaxis cases where triggering allergen is not identified, thorough history taking should include a potential tick bite. The longer duration from allergen exposure to symptom onset is one of the key characteristics of this unique reaction.
Conclusions: The present case illustrated a unique cause of delayed allergic reaction induced by Amblyomma Americanum. Identifying tick bite as a possible cause of anaphylaxis will allow hospitalists to provide appropriate care and instructions for patients to avoid recurrent anaphylaxis.
To cite this abstract:Uemura T, Misumida N. Unusual Cause of Anaphylaxis: What Is Hiding in a Belly?. Abstract published at Hospital Medicine 2016, March 6-9, San Diego, Calif. Abstract 692. Journal of Hospital Medicine. 2016; 11 (suppl 1). https://www.shmabstracts.com/abstract/unusual-cause-of-anaphylaxis-what-is-hiding-in-a-belly/. Accessed May 22, 2019.