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Can early tree nut ingestion prevent the development of tree nut allergy in peanut allergic/tree nut sensitised infants: to screen or not to screen?

AIFA Early Career and New Researcher Grant  

Ms Kayla Parker

Murdoch Children’s Research Institute (MCRI), Melbourne

Research Team: Prof Kirsten Perrett, A/Prof Rachel Peters, Dr Vicki McWilliam, Dr Victoria Soriano, Ms Audrey Walsh (MCRI)

Ms Kayla ParkerTree nut allergies are frequently life-long and severe as the accidental ingestion of tree nuts can risk life-threatening reactions involving IgE antibodies. Tree nut allergies are also common, affecting 3% of Australian children. Infants with a peanut allergy are at a higher risk of a tree nut allergy, with 40% developing a tree nut allergy by school-age.

Tree nut allergy can be a clinical and diagnostic challenge. Due to the increased risk of developing multi-nut allergies, infants with a peanut allergy often undergo tree nut IgE screening tests before introducing tree nuts into the diet to assess their risk of tree nut allergy. Positive screening results will often guide advice for strict tree nut avoidance until a diagnostic oral food challenge test (OFC). With ever-growing OFC waiting lists in an already overwhelmed healthcare system, this makes conducting potentially multiple individual tree nut OFCs nonviable to determine an infant’s allergy profile. Additionally, there is a lack of evidence to support this approach with international guidelines recommending against pre-ingestion screening. The delayed introduction, or complete avoidance, of tree nuts whilst waiting for an OFC may further increase the risk of developing a tree nut allergy.

This project will involve infants from the TreEat study, a randomised control trial investigating the safety and efficacy of early tree nut ingestion in preventing tree nut allergy in infants with a peanut allergy. Infants with a blood sample (n=125) taken before tree nuts were ever ingested (age 4 to 11 months) and at follow-up (age 18 months) will be included. Their blood IgE levels to cashew, hazelnut, walnut and almond will be measured pre- and post-ingestion, and their tree nut ingestion history and allergy outcomes at follow-up will be determined.

This research will provide world-first evidence on whether the early introduction of tree nuts can modify the association between tree nut IgE levels and allergy development among high-risk infants with peanut allergy. This research will also help inform clinical management by understanding whether infants with peanut allergy can safely introduce tree nuts into their diet irrespective of pre-ingestion screening results.