Réactions allergiques et dermatites à Thaumetopoea pityocampa. Revue critique à propos d’un cas

Abstract

A case of acute pruritic dermatitis occurring in an adult provided us with an opportunity to review the symptoms associated with pine processionary caterpillars. While out picking mushrooms in a pine forest, the patient developed pruritus (some 30minutes after entering the pine forest in which certain trees were infested with processionary caterpillars) and a papular rash occurred several hours later. The diagnosis was based on patient history, which included previous episodes, the appearance of the lesions, and negative allergy tests for allergens likely to occur in this biotope. Our case report is accompanied by a critical literature review. Allergy to pine processionary caterpillars is not associated with allergy to adult butterflies (imago) of the species. The allergenic protein (thaumetopoein) causes local and regional allergic reactions on exposed areas of skin and in conjunctival and respiratory mucosa (nasal, tracheal, bronchial). The major allergen is Tha p 2; a recombinant allergen, r Tha p 2, exists. Individuals allergic to pine processionary caterpillars may include professionals (forest workers) and non-professionals (walkers, holidaymakers, mushroom gatherers, etc.). Symptoms involve irritation (strophulus-like rash associated with urticating caterpillar hairs) or they may be IgE-dependent (conjunctivitis, rhinitis, asthma, and even anaphylaxis). Diagnosis is made primarily on clinical grounds. Prevention requires both individual and collective measures (nationally coordinated combat against the propagation of processionary caterpillars). It should also be noted that animals (particularly dogs) may also be affected, with potentially extremely serious symptoms in the event of ingestion.