Peanut Allergy and Peanut-specific IgG4 characteristics among Xhosa Children in Cape Town

Challenges of managing food allergy in the developing world

Food allergy (FA) is currently a significant health care problem in the developing world. Widely varying study populations and methodologies, the use of surrogate markers such as self report or hospitalization rates due to anaphylaxis rather than objective methods, limits robust estimation of FA prevalence in low income settings. Also, allergy is under-recognized as a clinical specialty in the developing world which compromises the chance for accurate diagnosis. In this review, most published data on food allergens from developing or low income countries are displayed. The diagnostic challenges and limitations of treatment options are discussed. It seems that FA is an under-appreciated health care issue in the developing world, and accurate determination of its burden in low-income settings represents an important unmet need. Multicenter surveillance studies, using standardized methodologies, are, therefore, needed to reveal the true extent of the problem and provide epidemiological clues for prevention. Preventive strategies should be tailored to fit local circumstances in different geographic regions. In addition, studying the gene environment interactions and impact of early life microbiota on the expression of FA in developing communities would be worthwhile. Efforts and resources should be directed toward public health education and training of health care providers dealing with food allergic patients.

Ethnic differences in peanut allergy patterns in South African children with atopic dermatitis

BACKGROUND

The prevalence of peanut allergy in South Africa is unknown, but previously thought to be low, particularly in black South Africans. This study aimed to determine the prevalence of component patterns and predictive values of screening tests in peanut allergy in South African children with atopic dermatitis (AD).

METHODOLOGY

This was a prospective, observational study in a pediatric university hospital in Cape Town. Children with AD, aged 6 months to 10 years, were recruited randomly. They were assessed for sensitization and allergy to peanut by questionnaire, skin prick tests (SPT), Immuno Solid Phase Allergen Chip test, ImmunoCAP component tests to Ara h 1, 2, 3, 8, and 9, and incremental food challenges.

RESULTS

A total of 100 participants (59 black Africans and 41 of mixed race) were enrolled, median age 42 months. There was a high and comparable rate of peanut sensitization in both black African (41%) and mixed race patients (50%), but a significantly lower prevalence of peanut allergy in the black African group (15% vs. 38%, p = 0.01). The component Ara h 2 was the most useful in differentiating allergy from tolerance in both ethnic groups, but had a significantly lower predictive value for peanut allergy in blacks (53%) vs. mixed race (93%). Overall, SPT and Ara h 2 produced the highest area under the receiver operating characteristic curve. A total of 95% positive predictive values (PPV) for SPT, peanut-specific IgE, and Ara h 2 levels varied significantly between the two ethnic groups.

CONCLUSION

The prevalence of peanut allergy is high in South African children with AD, but significantly lower in blacks compared to mixed race patients. The component Ara h 2 is useful for differentiating allergy from tolerance in both ethnic groups. Ninety-five% PPV for peanut allergy tests may need to be revised by ethnic group.

Food allergy in Africa: myth or reality?

Food allergy has been traditionally perceived as being rare in Africa. However, the prevalence of other allergic manifestations such as asthma and atopic dermatitis continue to rise in the higher-income African countries. Since the food allergy epidemic in westernized countries has lagged behind that of allergic respiratory conditions, we hypothesize that food allergy is increasing in Africa. This article systematically reviews the evidence for food allergy in Africa, obtained through searching databases including PubMed, Medline, MD Consult, and scholarly Google. Articles are divided into categories based on strength of methodological diagnosis of food allergy. Information was found for 11 African countries: Botswana, Democratic Republic of Congo, Ghana, Kenya, Morocco, Mozambique, Nigeria, South Africa, Tanzania, Tunisia, and Zimbabwe. Most studies reflect sensitization to food or self-reported symptoms. However, a few studies had more stringent diagnostic testing that is convincing for food allergy, mostly conducted in South Africa. Apart from the foods that commonly cause allergy in westernized countries, other regionally significant or novel food allergens may include pineapple (Ghana), okra (Nigeria), and mopane worm (Botswana). Food allergy is definitely an emerging disease in Africa and resources need to be diverted to study, diagnose, treat, and prevent this important disease.