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Peanut allergy in relation to heredity, maternal diet, and other atopic diseases: results of a questionnaire survey, skin prick testing, and food challenges

BMJ 1996; 313 doi: https://doi.org/10.1136/bmj.313.7056.518 (Published 31 August 1996) Cite this as: BMJ 1996;313:518
  1. J O'B Hourihane (jobh{at}soton.ac.uk), clinical research fellowa,
  2. T P Dean, senior research fellowa,
  3. J O Warner, professor of child healtha
  1. a Child Health, University of Southampton, Southampton General Hospital, Southampton SO16 6YD
  1. Correspondence and reprints to: Professor Warner.
  • Accepted 30 July 1996

Abstract

Objectives: To determine rates of other atopic manifestations in people with peanut allergy and the prevalence of such allergy in their families.

Design: A survey of people with self reported peanut allergy and people referred by their general practitioner for suspected peanut allergy; survey and skin testing of 50 children with reported peanut allergy and their available first degree relatives.

Subjects: 622 adults and children with reported, suspected, or known peanut allergy.

Main outcome measures: Prevalence of peanut allergy and other allergies in the families of people with peanut allergy.

Results: 622 valid completed questionnaires were returned out of the 833 questionnaires dispatched (74.7%). All forms of atopy were both more common in successive generations (P<0.0001) and more common in maternal than paternal relatives (P<0.0001). Peanut allergy was reported by 0.1% (3/2409) of grandparents, 0.6% (7/1213) of aunts and uncles, 1.6% (19/1218) of parents, and 6.9% (42/610) of siblings. Consumption of peanuts while pregnant or breast feeding was more common among mothers of probands aged </=5 years than mothers of probands aged >5 years (P<0.001). Age of onset correlated inversely with year of birth (r = -0.6, P<0.001). Skin prick testing of 50 children with reported peanut allergy and their families: 7 probands (14%) had a negative result for peanut. Peanut allergy was refuted by food challenge in all those tested (5/7). No parent and 13% (5/39) of siblings had a positive result on skin prick testing for peanut. Two of these siblings had negative challenge with peanuts. The prevalence of peanut allergy in siblings is therefore 3/39 (7%).

Conclusions: Peanut allergy is more common in siblings of people with peanut allergy than in the parents or the general population. Its apparently increasing prevalence may reflect a general increase of atopy, which is inherited more commonly from the mother. Peanut allergy is presenting earlier in life, possibly reflecting increased consumption of peanut by pregnant and nursing mothers.

Key messages

  • The apparent epidemic of peanut allergy is a reflection of the general increase in atopic diseases and increased case identification

  • The age of onset of peanut allergy is decreasing, possibly secondary to increased consumption by mothers and by infants early in life

  • Peanut allergy affects 7% of siblings of people with peanut allergy but only 1.3% of the general population

Footnotes

  • Funding This work was supported by a grant (to TPD) from the Ministry of Agriculture, Fisheries and Food.

  • Conflict of interest JO'BH is funded by the Seed Crushers and Oil Processors Association.

  • Accepted 30 July 1996
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