Global Courant
Eczema in young babies can be a sign that a child will develop more allergies.
New research, published Tuesday in the journal Pediatrics, confirms a phenomenon known as the “allergic march” — a pattern that describes the way allergies develop and progress in children, starting in infancy through age 3.
The study, which analyzed data from medical records collected from more than 200,000 children between 1999 and 2020, found that children were first diagnosed with eczema, also known as atopic dermatitis, after an average of 4 months. Next came diagnoses of food allergies that cause symptoms ranging from hives to anaphylaxis — a life-threatening allergic reaction that affects the entire body and can cause the airways to swell and close — and asthma, both at about 13 months old. After 26 months, the study found, children developed allergic rhinitis, or hay fever. In rare cases, after 35 months, children can develop a fifth allergy called eosinophilic esophagitis.
Dr. Stanislaw Gabryszewski, a fellow in the Department of Allergy and Immunology at Children’s Hospital of Philadelphia who led the study, said the “allergic march” doesn’t mean every child with eczema will develop every allergy described.
“Every child is different. Some may have one, others may have some, others may have all of them,” he said.
About 1 in 5 children have one of these types of allergies, making them one of the most common chronic illnesses in children. Just over 13% of children have at least two types of allergic disease, the researchers said.
The findings are helpful to both parents and doctors, who can better monitor children who develop eczema early in life for other allergies later on.
“Eczema in infancy is the No. 1 risk factor for developing allergies later in life, far more so than family history,” said Dr. Ruchi Gupta, founder and director of the Center for Food Allergy and Asthma Research at Northwestern University and Lurie Children’s Hospital in Chicago, who was not involved in the study.
The medical community has long recognized the allergy march, but the new research is the largest study to confirm the pattern. And while previous research focused primarily on white children, about a third of the children in this study were black. About 10% were Hispanic and a smaller proportion – less than 3% – were Asian or Pacific Islander.
“This study adds another layer of evidence that allergic diseases start early in life, and there is a progression of allergic diseases that can co-occur so that one child can have multiple allergic diseases,” said Dr. Sharon Chinthrajah, an immunologist at Stanford University School of Medicine who was not involved in the study.
She added that sometimes the previous allergic conditions go away and the child only develops a food allergy, for example, but sometimes the allergies are cumulative, leaving children with multiple types of allergies. For some, certain allergies will come and go, Chinthrajah said.
Food allergies were less common than previous research has found, affecting about 4% of the children in the study, about half the number seen in studies where people self-reported their allergies. The most common food allergies were peanuts, eggs and shellfish. Patients with respiratory allergies such as asthma and allergic rhinitis usually had both conditions in addition to other allergic conditions.
The study also found that eosinophilic esophagitis — a rare form of food allergy that causes inflammation in the esophagus — affects a higher proportion of non-Caucasian children than previously thought. About 40% of the children with the condition were not white. Overall, this allergy was very rare, seen in only 0.1% of children.
A better understanding of how allergies usually develop could lead to treatments that can stop the progression — or prevent allergies from developing at all.
If eczema could be prevented, “can we prevent food allergies, environmental allergies and asthma?” Gupta asked. “We don’t know yet, but research is being done.”
Chithrajah agreed.
“Whereas our job as researchers is to identify how we intervene early and with those interventions, how do we affect not one of five allergic diseases, but many,” she said.
That research will need to untangle the link between environmental factors — including climate change, which exacerbates seasonal allergies — and genetics.
“Ultimately, it’s the interplay of the two that will determine which children develop allergies and, if they do, how severe they will be,” Gabryszewski said.
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