Dynamics of Allergy Development in Children

Atopic and Reverse Atopic March

Early childhood represents a critical period for the development of the immune system, hence allergies may first appear early in life. Studies show that the incidence of allergies has increased in recent decades and that they affect about 30% of children in Central Europe. Spergel and Paller state that atopy, i.e., the predisposition to allergy, leads to the sequential development of various clinical forms of allergy (atopic march), starting with atopic dermatitis (AD), followed by the occurrence of rhinoconjunctivitis (RK) and asthma. Barberio et al. describe the opposite development of atopic manifestations (reverse atopic march), i.e., the emergence of atopic dermatitis in children who previously only had asthma. There are also studies attempting to classify the manifestations of atopy into different genotypes.

Study Process and Results

The study was conducted in Slovakia between 1996 and 2000. Out of 1992 registered children, 320 were included, who exhibited atopic symptoms by the age of 5. The children were examined in 3 developmental periods: infancy (< 1 year, n = 64), toddlerhood (1−2 years, n = 145) and preschool age (2−5 years, n = 195); out of these, 84 children were examined 5 times (i.e., once a year).

During the first 5 years of life, a gradual increase in the incidence of allergic diseases was observed (p < 0.001). Atopic dermatitis was usually the first to appear. Out of 64 infants with atopic symptoms, 58 had AD. Atopic dermatitis, manifested in infancy in about one-third of children, disappeared in later ages. The persistence of atopic dermatitis without remissions and exacerbations and without other atopic manifestations was rare (in 6.9% of children with AD).

In toddlerhood and preschool age, the variability of symptoms increased, and AD combined with other manifestations. The occurrence of rhinoconjunctivitis rose from 1.3% in infants to 13.4% in toddlers and 36.6% in preschool children (both p < 0.001). Similarly, the incidence of wheezing increased with age. Asthma was diagnosed in 7.9% of 4-year-old children, with 40% of them having previously experienced wheezing. Urticaria first appeared between the ages of 2 and 5, with a single exception. In 39% of cases, it was combined with another atopic manifestation, and in 78% of the cases, it developed in children who had previously shown some atopic symptom. Food allergy was present in only 3.4% of infants, but in 55.6% of toddlers and 66.7% of preschool children.

Conclusion

The study by Slovak experts shows that the frequency of allergic diseases increases during the first 5 years of life. Multi-symptomatic allergies replace mono-symptomatic forms as age progresses. The observed dynamics of allergic symptoms correspond to the hypothesis of the sequential development of various clinical forms of allergy (atopic march). 

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Sources:
1. Vrbová M., Dorociaková P., Vyškovský R. et al. Dynamics of allergy development during the first 5 years of life. Eur J Pediatr 2018; 177 (9): 1317−1325, doi: 10.1007/s00431-018-3188-9.
2. Spergel J. M., Paller A. S. Atopic dermatitis and the atopic march. J Allergy Clin Immunol 2003; 112 (6 Suppl.): S118−S127, doi: 10.1016/j.jaci.2003.09.033.
3. Barberio G., Pajno G. B., Vita D. et al. Does a 'reverse' atopic march exist? Allergy 2008; 63 (12): 1630−1632, doi: 10.1111/j.1398-9995.2008.01710.x.