The aim of the study is to assess the prevalence of peanut, tree nuts, and sesame allergy in Polish children at high risk of food allergy. Additionally, the timing of the development of peanut, tree nuts and sesame allergy in the first three years of life in a high-risk population will be assessed.

Introduction: Peanut allergy (PA) has become a health concern world-wide for several decades. Sesame allergy, although less prevalent, is also causing growing concern. Peanut, tree nuts, and sesame allergy co-exist in 60% of children. Although the majority of PA cases come from the general population, there are well-established risk factors for this allergy, such as eczema and egg allergy. In the Learning Early About Peanut (LEAP) Study, early introduction of peanut into the diet of children with moderate-to-severe eczema or egg allergy was proven to be effective in PA prevention. This strategy has now been adopted by national allergy societies in the USA and Australia as part of the weaning guidance for the high-risk populations.However, it is not known whether early introduction of peanut is also justified in other populations where peanut consumption has traditionally been lower. Getting insight into the prevalence of nut and sesame allergy in the cohort of infants and toddlers in Central Europe is needed to guide early dietary intervention strategies.

Methods: 240 children with eczema or egg allergy will undertake extensive assessment of peanut, tree nuts (hazelnut, almond, cashew, pistachio, walnut, macadamia) and sesame allergy status through consumption history, skin testing, specific immunoglobulin E measurement (sIgE) and oral food challenges (OFCs).

Inclusion Criteria:

• moderate or severe eczema and/or egg allergy,
• at least one complementary food already introduced,
• signed informed consent.

Assessment of eczema severity: Eczema severity will be assessed based on the objective SCORing Atopic Dermatitis (SCORAD), use of topical steroids, calcineurin inhibitors or systemic treatment as well as history of hospital admission.

Definition of egg allergy: Participants with a documented IgE-mediated egg allergy will be identified by a convincing history of a reaction in the presence of a positive skin prick test (SPT) (wheal diameter of 3 mm or greater with egg white extract) or an SPT ≥ 5mm with no history of a reaction.

Exclusion Criteria:

• inability to withdraw antihistamines for at least 5 days prior to testing,
• use of prohibited medication such as beta-blockers, angiotensin-converting-enzyme inhibitors (ACE-I) and biological treatments affecting the immunological response,
• uncontrolled asthma or eczema which does not warrant readiness for a food challenge within the study time frame,
• chronic urticaria,
• chronic systemic diseases.

The children will be recruited using mailing to general paediatric, allergy, and dermatology practices and directly to two allergy centers (Warsaw and Bydgoszcz).

The datasets used and/or generated during this study will be made available after the publication of results, no later than 3 years from the completion of data analysis.

Up to 3 years after completion of data analysis.

The datasets will be made available from the contact author upon reasonable request.