Author: V. Dimov, M.D., Allergist/Immunologist and Assistant Professor at University of Chicago
Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at NSU
A 35-year-old female is seen in the allergy clinic for evaluation of of suspected food allergy. Three months ago, she had abdominal discomfort and shortness of breath within minutes of eating chocolate-covered almonds. She had a methacholine challenge test which was negative. She is here to determine if food or environmental allergies played a role in her symptoms.
Past Medical History: negative.
Medications: none. NKDA.
Physical Examination: HEENT: "allergic shiners". Otherwise unremrkable.
What is the most likely diagnosis?
Food allergy is on the list of differential diagnoses.
What type of diagnostic tests would you suggest?
She had percutaneous skin testing with indoor, outdoor, and food allergens.
Airborne allergens: Positive for Cockroach. Negative for Dust mite, Cat, Dog, Mold, Trees, Grass, Weeds, Ragweed.
Food allergens: negative for Tree nuts (almond, walnut, sesame, hazelnut, pistachio, Brazil nut). Egg, Milk, Peanut, Soy, Wheat, Fish, Shellfish.
Female Blatella germanica cockroach with ootheca (eggs). Image source: Wikipedia, public domain.
What is the cause of this patient’s symptoms?
Allergic rhinitis with sensitization to cockroach. Suspected food allergy with symptoms related to cross-contamination with cockroach.
Patients who consume food products contaminated with cockroach parts such as chocolate or nuts may have an allergic reaction. Her reaction to chocolate-covered almonds could be related to cross-contamination with cockroach. On average, 8 insect parts are found per chocolate bar and deemed safe for most people, according to the FDA’s guidelines.
Skin testing has a 30% greater sensitivity than serum IgE (Cleveland Clinic J of Med, 2011, 78-9, 585-592), and a negative skin test typically rules out clinical environmental or food allergy in approximately 90% of patients.
What would you suggest to prevent future reactions?
Regarding her allergic rhinitis, we recommended avoidance of relevant allergens cetirizine 10 mg po qpm to be used as needed.
Regarding the suspected food allergy, we recommended complete avoidance of tree nuts and peanut due to cross-contamination risk and pending workup for food allergy. EpiPen was prescribed, and she was educated on its use. In case of anaphylaxis, she should call 911. We also provided a food allergy action plan and links to the educational videos on our teaching web site, AllergyCases.org.
An oral food challenge with almond was suggested to rule out food allergy to almond conclusively.
Chocolate Allergy? It's Vanishingly Rare
"Chocolate Allergy" is actually due to cockroach in chocolate - up to 60 insect parts per 100 gm bar "acceptable". ABC News, 2012.
FDA Info sheet