Roger Twiselton

Cohort study of peanut and tree nut sensitisation by age of 4 years.

Abstract Objective: To determine the prevalence of sensitisation to peanuts and tree nuts in all children born during one year in one geographical area. Design: Birth cohort study with structured review at ages 1, 2, and 4 years. Setting: All children born on the Isle of Wight between January 1989 and February 1990. Subjects: Of 1456 children originally included, 1218 were reviewed at age 4 years. Of these, 981 had skin prick tests. Main outcome measures: Positive skin test results, clinical atopic disease, and risk factors for the development of atopy. Results: 15 of 1218 (1.2%) children were sensitised to peanuts or tree nuts (13 to peanuts). Six had had allergic reactions to peanuts (0.5% of the population), one to hazelnuts, and one to cashew nuts; three had had anaphylactic reactions. Seven children had positive skin test results or detectable IgE to peanuts without clinical symptoms. Two children who reacted to peanut in infancy had lost their sensitivity by 4 years. Family history of atopy, allergy to egg (odds ratio 9.9, 95% confidence interval 2.1 to 47.9, and eczema (7.3, 2.1 to 26.1) were important predictors for peanut allergy. Conclusions: IgE mediated allergy to peanuts is common in early childhood. In many the allergy persists but a minority may develop tolerance. Key messages Key messages This study suggests that 1 in 200 children could have reactions to peanuts and tree nuts by the age of 4 years and a similar number could have asymp- tomatic sensitisation Children with allergy to peanuts invariably have another atopic disorder such as asthma, eczema, or rhinitis Sensitisation to peanuts and tree nuts may coexist

Effect of allergen avoidance in infancy on allergic manifestations at age two years

BACKGROUND One hundred twenty children, identified before birth as being at high risk for atopy, were prenatally assigned to prophylactic or control groups. METHODS The infants in the prophylactic group either received breast milk from mothers on an exclusion diet or an extensively hydrolyzed formula. Their bedrooms and living rooms were treated repeatedly with an acaricide, and they used polyvinyl-covered mattresses with vented head areas. The infants in the control group were fed conventionally, and no environmental control was recommended. RESULTS A significant advantage, first demonstrated at 1 year of age, persists for children in the prophylactic group. They have less of any allergy or eczema, but the reduced prevalence of asthma is no longer significant. Only three children in the prophylactic group had positive skin prick test results compared with 16 in the control group, suggesting a significant reduction in sensitization. CONCLUSION A dual approach to allergen avoidance, focusing on foods and aeroallergens, appears to be beneficial in selected high-risk infants. Avoidance of potent allergens in early life increases the threshold for sensitization in these high-risk infants. Whether sensitization has been avoided or merely deferred has yet to be proved.

Cord serum IgE: an insensitive method for prediction of atopy

Cord total serum IgE has been advocated as a screening test to detect infants at high risk of allergy who would be suitable for preventive measures. In a population based prospective study to look at the predictive capacity of cord IgF and family history of atopy 1111 one‐year‐old infants were followed‐up. Cord IgE was measured using the EIA ultra technique (Pharmacia, Uppsala, Sweden). Atopic symptoms developed in 255 (23%) at one year, 183 (16·5%) had probable atopy (clinical disorder but negative skin prick test (SPT)) and 72 (6·5%) had definite atopy (clinical disorder with positive SPT), There was no difference in the mean cord IgE levels in infants with or without atopic manifestations. The cut‐off for IgF was taken at 0·6 ku/1. The specificity of the test was 92% but the sensitivity was only 8·5%. The positive and negative predictive values were 24% and 78% respectively. Family history of atopy is far more sensitive in detecting infants at risk of atopy and little is added by knowledge of cord IgE.

Passage of cows' milk protein in breast milk

An enzyme‐linked immunosorbent assay has been used to search for lactoglobulin and bovine casein in breast milk. Initial results suggest this may be a simple and useful method for such studies. Detection and prevention of antigen passage could influence the prevalence of atopic disease.

Does maternal immunoglobulin E decrease with increasing order of live offspring? Investigation into maternal immune tolerance.

Background Identifying the protective effect of a higher number of siblings is a significant finding in understanding the aetiology of allergic sensitization, asthma, eczema, and hayfever. Knowledge about causes behind the sibling effect may allow us to prevent atopic manifestations.

The prevalence, natural history and time trends of peanut allergy over the first 10 years of life in two cohorts born in the same geographical location 12 years apart

The aim of this study was to explore the natural history of peanut allergy in childhood in two birth cohorts from the same geographical region in the South of England.

The diagnosis of Brazil nut allergy using history, skin prick tests, serum-specific immunoglobulin E and food challenges

Background Allergy to Brazil nut is a relatively common nut allergy and can be fatal. However, the evidence is lacking regarding the best approach to its diagnosis.

Influence of genetic and environmental factors on the level of IgE at birth

The effect of hereditary and environmental factors on the level of IgE at birlh was assessed in 1319 unselected infants. Cord igE was measured using a new enzyme‐linked immunoassay. EIA Ultra® test. Information on family history of atopy and maternal smoking was obtained using a standard questionnaire. Data on length of gestation and birth weight were obtained from hospital records. Blood for maternal IgE was obtained from 1056 mothers within a week of delivery. Cord IgE levels were higher in infants with a history of atopy in the immediate family (p < 0.01). Male infants had a higher IgE than female (p < 0.01). Maternal IgE correlated positively with cord IgE (r = 0. 3, p < 0.001). There was no effect of length of gestation, birth weight, maternal smoking or month of birth on cord IgE values. It is concluded that the IgE level at birth is determined primarily by genetic factors. No significant effect of environmental factors was demonstrated in this study.

Prevalence and cumulative incidence of food hyper‐sensitivity in the first 10 years of life

Prevalence, incidence and natural history of food hypersensitivity (FHS) and its trends in an unselected cohort of older children are unclear.