Prevalence and Manifestations of Cow Milk Protein Allergy
The prevalence of food allergies is on the rise, along with the severity and variety of their manifestations. The most common food allergy in infants and toddlers is cow milk protein allergy (CMPA).
Current Statistics
The prevalence of cow milk protein allergy in food allergies reaches 2-5% in infants and toddlers according to data from the DAFALL (Database of Food Allergies) on a European scale. More patients are male (59.3%) than female (40.7%). In the Czech Republic, according to DAFALL data from 2014 to 2017, this allergy is diagnosed in 84% of infants suffering from some kind of food allergy.
First manifestations of cow milk protein allergy are usually observed during breastfeeding, as infants react to these proteins present in breast milk. According to the DAFALL registry, 5% of patients show the first signs of allergy by 1 month of age, 59% by 3 months of age, and a minority (14%) start to develop problems at 7 months or later. In 65.6% of infants with CMPA, the first signs appeared during full breastfeeding. Some children react when switching from breastfeeding to formula or upon the introduction of the first dairy solid. In most cases (90%), the onset of cow milk protein allergy occurs within the first year of life.
Allergens in Cow Milk
An allergic reaction may be triggered by any of the 40 proteins present in cow milk.
The main allergens are caseins (curd proteins) and alpha-lactalbumin and beta-lactoglobulin (whey proteins). Casein is a thermostable allergen, and allergic reactions in the case of casein are usually more severe than with thermolabile whey proteins. In exclusively breastfed infants, however, the main allergen is beta-lactoglobulin.
Some patients also react to secondary allergens: serum albumin, lactoferrin, and immunoglobulins (proteins derived from cow blood serum).
Patients with a cow milk protein allergy often experience allergic reactions to other types of animal milk, such as goat's milk (which is up to 95% homologous with cow milk), sheep milk, and buffalo milk.
Manifestations of Allergy: Early and Late
Manifestations of cow milk protein allergy are divided into early and late.
Early manifestations are usually mediated by IgE antibodies, appearing approximately within 2 hours of protein ingestion and including symptoms such as rhinitis, cough, dyspnea, urticaria, or itching. Other symptoms can include swelling, abdominal pain, or vomiting. According to the DAFALL database, early manifestations are recorded in 48% of patients with cow milk protein allergy.
Late manifestations of allergy arise between 2 hours and 3 days after the consumption of cow milk protein and typically involve a different type of immunopathological reaction without evidence of IgE antibodies (so-called non-IgE mechanism). Late manifestations include eczema, digestive issues (diarrhea, blood and mucus in the stool), food refusal, sleep disturbances, and behavioral changes.
The most severe reaction to cow milk proteins is anaphylactic shock. According to available data from the DAFALL database, anaphylaxis affects approximately 2% of patients.
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Sources:
1. Bělohlávková S. et al. Register of Food Allergies in the Czech Republic DAFALL – 3 years of monitoring. XXXIV. Congress SSAKI and ČSAKI, Tatry, October 2017.
2. Bělohlávková S. Cow Milk Protein Allergy – Occurrence and Manifestations. Ewopharma, 2018.
3. Fuchs M. et al. Food Allergy and Intolerance. Mladá fronta, Prague, 2016.
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