Connect
MJA
MJA

The Australasian Society of Clinical Immunology and Allergy position statement: summary of allergy prevention in children

Susan L Prescott and Mimi LK Tang
Med J Aust 2005; 182 (9): 464-467. || doi: 10.5694/j.1326-5377.2005.tb06787.x
Published online: 2 May 2005

Abstract

  • A family history of allergy and asthma identifies children at high risk of allergic disease.

  • Dietary restrictions in pregnancy are not recommended.

  • Avoiding inhalant allergens during pregnancy has not been shown to reduce allergic disease, and is not recommended.

  • Breastfeeding should be recommended because of other beneficial effects, but if breast feeding is not possible, a hydrolysed formula is recommended (rather than conventional cow’s milk formulas) in high-risk infants only.

  • Maternal dietary restrictions during breastfeeding are not recommended.

  • Soy formulas and other formulas (eg, goat’s milk) are not recommended for reducing food allergy risk.

  • Complementary foods (including normal cow’s milk formulas) should be delayed until a child is aged at least 4–6 months, but a preventive effect from this measure has only been demonstrated in high-risk infants.

  • There is no evidence that an elimination diet after age 4–6 months has a protective effect, although this needs additional investigation.

  • Further research is needed to determine the relationship between house dust mite exposure at an early age and the development of sensitisation and disease; no recommendation can yet be made about avoidance measures for preventing allergic disease.

  • No recommendations can be made about exposure to pets in early life and the development of allergic disease. If a family already has pets it is not necessary to remove them, unless the child develops evidence of pet allergy (as assessed by an allergy specialist).

  • Women should be advised not to smoke while pregnant, and parents should be advised not to smoke.

  • No recommendations can be made on the use of probiotic supplements (or other microbial agents) for preventing allergic disease at this time.

  • Immunotherapy may be considered as a treatment option for children with allergic rhinitis, and may prevent the subsequent development of asthma.

In the second half of the 20th century, asthma and other allergic diseases became dramatically more common in Western countries, and Australia has one of the highest allergy prevalence rates in the world. Up to 40% of Australian children have evidence of allergic sensitisation, and many will go on to develop allergic diseases such as food allergies, eczema, asthma and allergic rhinitis. These conditions frequently persist into adulthood, placing a significant burden on individuals and the health care system. It is self-evident that environmental changes must be responsible for the increasing propensity for allergic disease. There is an ongoing search for causal associations that will help to identify strategies to reverse this trend. Strategies that reduce the risk or the severity of disease expression could have enormous impact. At this stage, most allergy prevention strategies are relatively crude, with small or unconfirmed effects, and newer strategies are still in experimental stages.

The complete Australasian Society of Clinical Immunology and Allergy (ASCIA) position paper on allergy prevention in children summarises the existing evidence with the aim of informing and refining current guidelines for allergy prevention. It is available at <http://www.allergy.org.au/pospapers/Allergy_prevention.htm>. Here, we present a concise summary of that position statement, outlining details most relevant for clinicians and areas that require further research. The “strength of recommendations” are based on the World Health Organization (WHO) “Categories of Evidence” wherever possible (see Box). In many areas the evidence is non-existent or is not particularly robust.

The role of allergens

The guiding principle behind allergen avoidance strategies is the hypothesis that reducing allergen levels may reduce the risk of allergen sensitisation, and hence the risk of allergic disease. However, despite a clear association between sensitisation and the development of allergic disease, the processes leading to sensitisation appear to be independent to those leading to disease. Moreover, in many cases, allergen avoidance strategies have been ineffective in reducing allergic sensitisation or associated with unexpected paradoxical effects. For example, although successful house dust mite (HDM) reduction in pregnancy has been associated with better lung function in preschool children, the same study showed an increased risk of sensitisation to HDM.2

Maternal allergen avoidance during lactation

There is no convincing evidence that allergen avoidance during lactation has a protective effect. Although several studies indicate that maternal avoidance of potential food allergens (milk, egg, and fish) while breastfeeding may reduce the risk of atopic eczema in the first years of life, other studies do not confirm this (details of these studies are available at <http://www.allergy.org.au/pospapers/Allergy_prevention.htm>). While a systematic Cochrane review suggested some benefits on early atopic eczema, methodological limitations make the findings difficult to interpret.8

Infant formulas

The most recent Cochrane reviews of allergy and infant feeding concluded that hydrolysed formulas reduce the risk of infant allergy (compared with cow’s milk formulas),9 but that these hydrolysed formulas should not be offered in favour of breast milk for allergy prevention.9,10 Significant effects have been observed with both partially and extensively hydrolysed formulas,11 but because of great variations in study design and diagnostic criteria, the relative efficacy of the different formulas tested in different studies cannot be compared directly.

Prospective studies have shown that soy formulas are as allergenic as normal cow’s milk formulas,11 but some controversy remains. Soy formulas and other milks (such as goat’s milk formula) are not recommended for the prevention of allergic disease.

Infant diet

Studies suggest that delaying the introduction of solid foods may reduce the incidence, or delay the onset, of infantile allergic diseases in the first year of life, including atopic dermatitis, food12,13 and other allergies, and wheezing.10 However, these effects are modest, and long-term benefits are not certain. In children with existing sensitisations or overt allergic disease (or those deemed to be at high risk for other reasons), it has been common clinical practice to recommend avoidance of potentially allergenic foods such as egg and milk until 12 months of age, and peanuts, nuts and shellfish until after 2–4 years of age. This practice is based on a theoretical benefit to protect an “immature immune system”. Nevertheless, although the “benefit” is not known, the “costs” of doing nothing are perceived as high, and the “cost” of this intervention is relatively low. There is no evidence that avoiding peanuts, nuts and shellfish during early life is harmful for high-risk children.

Recommendations
Exposure to house dust mite

There is a dose relationship between house dust mite (HDM) population levels in the home and sensitisation to HDM.14 Stringent environmental control measures can dramatically reduce HDM numbers,15 and even less stringent measures (mite covers for bedding and washing instructions) significantly reduce HDM numbers.16

Although some studies have suggested benefits of reducing early HDM exposure, long-term data are still not available. Conflicting evidence15 and recent reports of increased sensitisation risk have raised concern.2 Further follow-up of ongoing cohorts is required before any recommendations can be made within the public health context.15

The role of pollutants and irritants

Maternal smoking in pregnancy has adverse effects on infant lung development.18 Parental smoking has also been associated with wheezing illness in early childhood.19 The relationship between cigarette smoke exposure and atopy is less clear.

The role of other indoor pollutants is poorly understood. In some populations, the use of home gas appliances has been associated with an increased risk of HDM sensitisation and subsequent respiratory symptoms,20 but this needs to be confirmed.

The future: primary allergy vaccination?

The use of allergen vaccines or preventive immunotherapy has long been proposed as one method of primary prevention.26 The enteric mucosal immune system plays an extremely efficient and pivotal role in the development of tolerance. Studies using “high dose” mucosal delivery of aeroallergen combinations in infants at high risk of allergic disease (or those with early evidence of sensitisation such as food allergy) are about to commence. Future methods of safely promoting tolerance in humans may include novel “allergen vaccine” strategies.

Concluding comments

There is a growing need to reduce the mounting personal, social and economic costs of allergic disease. While there has been some success in managing established disease, strategies to prevent the development of these processes will be of greater value in the long term.

Currently, our capacity to prevent allergic disease is constrained by limited understanding of disease pathogenesis and aetiological factors, particularly of the early exposures responsible for the recent increase in allergic disease. There is also an inability to accurately identify atopic individuals before sensitisation occurs. All of these areas need to be investigated more fully to determine how tolerance mechanisms can be promoted without adverse effects.

Further information

For the full ASCIA position paper on allergy prevention in children, including references and further information on allergy, asthma or immune diseases, visit http://www.allergy.org.au, the website of the Australasian Society of Clinical Immunology and Allergy (ASCIA). ASCIA is the peak professional body of Clinical Allergists and Immunologists in Australia and New Zealand.

  • Susan L Prescott1
  • Mimi LK Tang2

  • 1 School of Paediatrics and Child Health Research, University of Western Australia, Perth, WA.
  • 2 Department of Immunology, Royal Children's Hospital, Melbourne, VIC.


Correspondence: 

Acknowledgements: 

We thank ASCIA members, particularly those involved in the Paediatric Interest Group, for their comments on this position statement when it was circulated for review.

Competing interests:

None identified.

  • 1. Kjellman NI. Prediction and prevention of atopic allergy. Allergy 1998; 53: 67-71.
  • 2. Woodcock A, Lowe LA, Murray CS, et al. Early life environmental control: effect on symptoms, sensitization, and lung function at age 3 years. NAC Manchester Asthma and Allergy Study Group. Am J Respir Crit Care Med 2004; 170: 433-439.
  • 3. Kramer MS, Kakuma R. Maternal dietary antigen avoidance during pregnancy and/or lactation for preventing or treating atopic disease in the child. Cochrane Database Syst Rev 2003; (4): CD000133.
  • 4. Foucard T. Is prevention of allergy and asthma possible? Acta Paediatr Suppl 2000; 89: 71-75.
  • 5. Schoetzau A, Filipiak-Pittroff B, Franke K, et al. Effect of exclusive breast-feeding and early solid food avoidance on the incidence of atopic dermatitis in high-risk infants at 1 year of age. Pediatr Allergy Immunol 2002; 13: 234-242.
  • 6. Oddy WH, Holt PG, Sly PD, et al. Association between breast feeding and asthma in 6 year old children: findings of a prospective birth cohort study. BMJ 1999; 319: 815-819.
  • 7. Gdalevich M, Mimouni D, Mimouni M. Breast-feeding and the risk of bronchial asthma in childhood: a systematic review with meta-analysis of prospective studies. J Pediatr 2001; 139: 261-266.
  • 8. Kramer MS. Maternal antigen avoidance during lactation for preventing atopic disease in infants of women at high risk. Cochrane Database Syst Rev 2000; (2): CD000132.
  • 9. Osborn DA, Sinn J. Formulas containing hydrolysed protein for prevention of allergy and food intolerance in infants. Cochrane Database Syst Rev 2003; (3). Art. No.: CD003664. DOI: 10.1002/14651858.CD003664.
  • 10. Ram FS, Ducharme FM, Scarlett J. Cow’s milk protein avoidance and development of childhood wheeze in children with a family history of atopy. Cochrane Database Syst Rev 2002; (1). Art. No.: CD003795. DOI: 10.1002/14651858.CD003795.
  • 11. Burr ML, Limb ES, Maguire MJ, et al. Infant feeding, wheezing, and allergy: a prospective study. Arch Dis Child 1993; 68: 724-728.
  • 12. Falth-Magnusson K, Kjellman NI. Allergy prevention by maternal elimination diet during late pregnancy — a five year follow-up of a randomised trial. J Allergy Clin Immunol 1992; 89: 709-713.
  • 13. Zeiger R, Heller S. The development and prediction of atopy in high-risk children: follow-up at age seven years in a prospective randomized study of combined maternal and infant food allergen avoidance. J Allergy Clin Immunol 1995; 96: 1179-1190.
  • 14. Platts-Mills TA, Rakes G, Heymann PW. The relevance of allergen exposure to the development of asthma in childhood. J Allergy Clin Immunol 2000; 105: S503-S508.
  • 15. Gore C, Custovic A. Can we prevent allergy? Allergy 2004; 59: 151-161.
  • 16. Koopman LP, van Strien RT, Kerkhof M, et al. Placebo-controlled trial of house dust mite-impermeable mattress covers: effect on symptoms in early childhood. Am J Respir Crit Care Med 2002; 166: 307-313.
  • 17. Apelberg BJ, Aoki Y, Jaakkola JJ. Systematic review: exposure to pets and risk of asthma and asthma-like symptoms. J Allergy Clin Immunol 2001; 107: 455-460.
  • 18. Stick SM, Burton PR, Gurrin L, et al. Effects of maternal smoking during pregnancy and a family history of asthma on respiratory function in newborn infants. Lancet 1996; 348: 1060-1064.
  • 19. Martinez FD, Cline M, Burrows B. Increased incidence of asthma in children of smoking mothers. Pediatrics 1992; 89: 21-26.
  • 20. Ponsonby AL, Dwyer T, Kemp A, et al. A prospective study of the association between home gas appliance use during infancy and subsequent dust mite sensitization and lung function in childhood. Clin Exp Allergy 2001; 31: 1544-1552.
  • 21. Kalliomaki M, Salminen S, Poussa T, et al. Probiotics and prevention of atopic disease: 4-year follow-up of a randomised placebo-controlled trial. Lancet 2003; 361: 1869-1871.
  • 22. Mihrshahi S, Peat JK, Marks GB, et al. Eighteen-month outcomes of house dust mite avoidance and dietary fatty acid modification in the Childhood Asthma Prevention Study (CAPS). J Allergy Clin Immunol 2003; 111: 162-168.
  • 23. Peat JK, Mihrshahi S, Kemp AS, et al. Three-year outcomes of dietary fatty acid modification and house dust mite reduction in the Childhood Asthma Prevention Study. J Allergy Clin Immunol 2004; 114: 807-813.
  • 24. Moller C, Dreborg S, Ferdousi HA, et al. Pollen immunotherapy reduces the development of asthma in children with seasonal rhinoconjunctivitis (the PAT-study). J Allergy Clin Immunol 2002; 109: 251-256.
  • 25. Pajno GB, Bearberio G, De Luca F, et al. Prevention of new sensitisations in asthmatic children monosensitised to house dust mite by specific immunotherapy. A six year follow-up study. Clin Exp Allergy 2001; 31: 1392-1397.
  • 26. Holt PG. A potential vaccine strategy for asthma and allied atopic diseases during early childhood. Lancet 1994; 344: 456-458.

Author

remove_circle_outline Delete Author
add_circle_outline Add Author

Comment
Do you have any competing interests to declare? *

I/we agree to assign copyright to the Medical Journal of Australia and agree to the Conditions of publication *
I/we agree to the Terms of use of the Medical Journal of Australia *
Email me when people comment on this article

Online responses are no longer available. Please refer to our instructions for authors page for more information.