Anisakis, anisakiasis and IgE-mediated immunity to Anisakis simplex

Area of Science:

• Parasitology
• Clinical Medicine
• Allergy and Immunology

Background:

• Anisakis simplex is a parasite found in fish and cephalopods.
• It can cause anisakiasis in humans and has been linked to anaphylactic reactions.
• Diagnosis can be challenging, especially when larvae are not visualized.

Purpose of the Study:

• To present a clinical case of a patient with suspected anisakiasis and confirmed IgE-mediated allergy to Anisakis simplex.
• To discuss the diagnostic challenges and clinical presentation of this dual condition.

Main Methods:

• Clinical case presentation of a 56-year-old male with recurrent gastrointestinal distress and anaphylaxis after fish consumption.
• Diagnostic procedures included skin prick tests, specific IgE determination, hemogram, copro-cultures, gastroscopy, intestinal imaging, and duodenal biopsies.
• Treatment involved a fish-free diet and thiabendazole.

Main Results:

• The patient exhibited anaphylactic reactions and severe epigastric pain, nausea, and vomiting.
• Specific IgE and skin tests for A. simplex were positive.
• Biopsies revealed chronic inflammation with eosinophilic infiltrate; intestinal imaging showed duodenal and jejunal dilation.
• The patient improved significantly after dietary changes and thiabendazole treatment.

Conclusions:

• The case strongly suggests coexisting IgE-mediated allergy to A. simplex and suspected anisakiasis, despite the absence of visualized larvae.
• The clinical presentation, diagnostic findings, and treatment response support the diagnosis.
• This case underscores the importance of considering anisakiasis in patients with relevant exposure and symptoms, even with negative larval detection.