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Background: Setae from Thaumetopoea pityocampa larvae (the pine processionary moth or PPM) can induce hypersensitivity reactions, but their clinical role in IgE-mediated responses is still subject to discussion. The aim of this study was to evaluate a setae extract for in vivo and in vitro diagnosis in nonhospitalized patients with reactions to PPM. Methods: Forty-eight adult patients presenting with PPM cutaneous reactions were studied by skin prick test (SPT) and specific IgE using setae and whole larval (WL) extracts. Biological standardized extracts were used for skin tests. Results: A total of 47.9% patients had a positive SPT for PPM (70% to both extracts, 17% only to the WL extract and 13% only to the setae extract). IgE immunoblotting detected several reactive bands in 91% of the SPT-positive cases. In multivariate analysis, male sex, immediate latency (<1 h) and duration of skin symptoms (<24 h) were independent predictors of a positive SPT. Conclusions: IgE sensitization to PPM was found in 48% of the study patients, which was associated with immediate reactions and evanescent cutaneous lesions. Most of these patients reacted to both WL and setae extracts, but some reacted to only one of them. According to our data, skin and in vitro tests to PPM should be performed using both extracts.

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Thaumetopoea pityocampa causes allergies and skin and ocular lesions. No commercial tools are currently available for the clinical diagnosis of this allergy. We aimed to develop an in vitro method for the diagnosis of this allergy to avoid patients undergoing in vivo tests with insect extracts. Recombinant Tha p 2 was produced and used in an ELISA validated with 15 allergic patients. Subsequently, 42 subjects recruited from a random sampling cross-sectional study were analysed. The ELISA sensitivity and specificity were 93.3% and 100%, respectively, for the allergic patients and 71.4% and 95.3%, respectively, for the epidemiological study. The positive ELISA results correlated with the skin prick test areas with the whole body and the setae extracts. Professional exposure and short latency of symptoms onset were risk factors for a positive result in the ELISA. In conclusion, our ELISA is very useful for T. pityocampa allergy diagnosis and for epidemiologic testing.