Molecular allergen sensitization profile and casein threshold determination predicting the persistence of cow's milk protein allergy in Tunisia (North Africa)

Yasmina Ouerdani ^1,2 Imen Zamali ^1,3,4 Yousr Galai ^1,5 Ahlem Ben Hmid ^1,3,4 Yosra Nasri ¹ Ines Ben Sghaier ¹ Hayet Kebaier ¹ Louzir Hechmi ^1,3,4 Jihene Bouguila ^2,6 Nissaf Ben alaya Bouafif ^4,7 Melika Ben Ahmed ^1,3,4 Samar Samoud ^1,2,3*

• ¹ Department of Clinical Immunology, Pasteur Institute of Tunis, Tunisia, Tunis, Tunisia
• ² Medical faculty Ibn Jazzar, University of Sousse, Sousse, Tunisia
• ³ Laboratory of Transmission Control and Immunobiology of Infections, Pasteur Institute of Tunis, Tunis, Tunisia
• ⁴ Faculty of Medicine, Tunis El Manar University, Tunis, Tunis, Tunisia
• ⁵ Faculty of Pharmacy of Monastir, University of Monastir, Tunisia, Monastir, Tunisia
• ⁶ Department of Pediatrics, Hospital Farhat Hached, Sousse, Tunisia, Sousse, Tunisia
• ⁷ National Observatory of New and Emerging Diseases, Ministry of Health, Tunis, Tunisia

Background: Cow's milk protein allergy (CMPA) represents a major health concern in Tunisia, with diagnostic challenges influencing disease prognosis. Molecular allergen testing has emerged as a valuable tool to enhance diagnostic accuracy and predict disease persistence. Objective: This study aims to characterize the clinical and epidemiological features of CMPA in a Tunisian population, with a particular focus on the role of molecular allergens in assessing disease chronicity. Methods: A retrospective analysis was conducted on 262 cases of IgE-mediated CMPA diagnosed at the Pasteur Institute of Tunis between 2020 and 2023. Sensitization to molecular allergens was assessed using ImmunoCAP (Phadia 100). Results: CMPA symptoms predominantly manifested in infancy (94%, 246/262), with a male predominance (sex ratio: 1.6). Acute reactions were the most frequent presentation (69.9%, 79/113), and polysensitization was common (81%, 212/262), particularly to βlactoglobulin. Spontaneous resolution occurred in approximately 33% of cases (29/87), with a mean age of 3 years and 8 months. Persistent CMPA was significantly associated with elevated IgE levels to whole milk, β-lactoglobulin, and casein (p < 0.05). ROC curve analysis identified predictive thresholds for disease persistence, including 4.2 kU/L for whole milk-specific IgE and 0.37 kU/L for casein-specific IgE (p = 0.006). Conclusion: Molecular allergen testing improves CMPA diagnosis and offers critical prognostic insights. The identification of IgE thresholds may facilitate early risk stratification and guide personalized management strategies.