Aim: To identify the differential risk of peanut allergies among Chinese children in the U.S and China.
Introduction: Peanut allergy is a very common allergy among American children. Though the exact number of people affected by this condition is not known, millions of people in U.S suffer from peanut allergies, and the number is increasing. The reason for the high prevalence of this condition is not known. While in most children, the condition persists throughout life, in a few, it will subside and eventually disappears with growth and age. Unlike almonds, cashews and walnuts that grow on trees, peanuts grow underground and belong to the legume family. Peanut allergy accounts for majority of the food related severe anaphylactic reaction. In spite of the high prevalence of peanut allergies and incidence of death associated with this allergy, there has been no significant step to reduce its occurrence. Sensitization to peanuts can occur very early in life. In most children, the allergy is identified before their second birthday (Pansare & Kamat, 2009). The peanut consumed during pregnancy is capable of causing anaphylactic reaction in the developing fetus (Pansare & Kamat, 2009). Peanut protein can also escape breast milk and sensitize the baby. Infant milk formula and vitamin preparations, contaminated with peanut oil can set in adverse hypersensitivity reaction in the baby (Pansare & Kamat, 2009). In spite of Food allergen labelling and Consumer Protection Act’s requirement to indicate ‘Peanut’ on the label of food product that contain it, the incidence of allergy is high and the seriousness of the situation is ignored. When compared to adults, the allergic symptoms are less severe in children. In China, peanut allergy is almost non prevalent, in spite of the high level of peanut consumption. Peanut and peanut oil is a regular part of the Chinese cuisine. Allergies tend to be common in developed countries, when compared to developing countries like China. In this study a comparative study will be done among Chinese children in U.S and China, to identify the prevalence of this condition.
Review of Literature: Most food allergies, including peanut allergies are IgE mediated. These allergies are a consequence of maladaptive immune response. The incidence of such food allergies are common in developed countries when compared to developing countries. The reason for this is not completely understood. Environmental factors, rather than genetic factors are suspected for this differential occurrence. Vitamin D deficiencies, intestinal parasites, hygiene, microflora composition of the bowel, climate, food composition, have all been suspected as reasons for this scenario.
Chinese herbal formula is capable of completely eliminating peanut allergies in mice by suppressing TH2 response. Probably, Chinese indigenous lifestyle is capable of offering protection to allergies associated with peanut consumption. The way peanut is processed, could also be responsible for altering the antigenicity of peanut. In U.S, peanuts are consumed mostly in roasted form, while in Chinese cuisine it is either fried or boiled. Roasting peanuts, was found to increase its antigenicity, while boiling and frying did not (Beyer et al., 2001).
Even in China, the incidence of peanut allergies has risen with time. Adoption of new lifestyle as a result of modernization or rising pollutant level, could be predisposing the population to the allergy. The prevalence of peanut allergies among infants, as identified by a positive skin prick test was 3.3% in 1999 and it increased to 7.7% in 2009 (Hu, Chen & Li, 2010).
According to a self-reported survey, the incidence of food allergy has increased by 18% from 1997 to 2007 (Branum & Lukacs, 2008). Children who begin to consume peanut from infancy are less likely to develop allergies when compared to those who are introduced to this food in later life. Being an integral part of Chinese cuisine, early introduction is more probable in Chinese children, when compared to U.S children (Du Toit et al., 2008).
Research design, materials and methods: The prevalence of peanut allergies will be tested on 1000 children each in China and U.S, in a cross sectional study. The prevalence of peanut allergy will be identified using a positive skin prick test. The subjects will be selected randomly. Informed consent will be obtained from parents before inclusion of children into the study. The study does not contain harmful protocol and all precautions will be carried out to ensure that the pin prick test is done safely. Subjects will be selected from a given geographical population in U.S and China.
Skin prick test helps confirm allergy towards food allergens or inhalant allergens. It is a simple, quick and safe test that can be completed in 15-20 minutes’ time. Though the test is usually performed in the skin of the inner forearm; in children, it can also be performed on the back or thigh to obtain a wider surface area of skin for the test. A drop of allergen is placed on the skin and then the skin is pricked slightly through this drop with a lancet. The prick may be sharp, but is not strong enough to cause pain or bleeding. A negative and positive control are included, to ensure that the test has been correctly performed. The positive reaction to the allergen is identified by the development of the itchy, red, swollen skin reaction with a weal at the center. Negative or no reaction to the allergen may occur when one is not allergic to peanut or due to intake of medications that suppress the positive reaction. Descriptive and Inferential statistical techniques will be used to analyze the data.
Expected outcome of the study and its future implication: This study is important in providing evidences to test the hypothesis of a favorable environment in US that supports the development of allergy in a less susceptible population. Peanut allergy is widely distributed in the U.S population and identifying the role of environmental, will help design further in-depth exploration into the topic. Modifying these factor will help prevent allergies. In spite of all the precaution taken to avoid peanuts, many children accidently consume it and develop serious hypersensitivity reaction. Understanding the environment, will help find an effective solution to this problem.
References:
Beyer, K., Morrowa, E., Li, X., Bardina, L., Bannon, G., Burks, A., & Sampson, H. (2001). Effects of cooking methods on peanut allergenicity. Journal Of Allergy And Clinical Immunology, 107(6), 1077-1081. http://dx.doi.org/10.1067/mai.2001.115480
Branum, A., & Lukacs, S. (2008). Food Allergy Among U.S. Children: Trends in Prevalence and Hospitalizations. NCHS Data Brief, 10, 1-7.
Du Toit, G., Katz, Y., Sasieni, P., Mesher, D., Maleki, S., & Fisher, H. et al. (2008). Early consumption of peanuts in infancy is associated with a low prevalence of peanut allergy. Journal Of Allergy And Clinical Immunology, 122(5), 984-991. http://dx.doi.org/10.1016/j.jaci.2008.08.039
Hu, Y., Chen, J., & Li, H. (2010). Comparison of food allergy prevalence among Chinese infants in Chongqing, 2009 versus 1999. Pediatrics International, 52(5), 820-824. http://dx.doi.org/10.1111/j.1442-200x.2010.03166.x
Pansare, M., & Kamat, D. (2009). Peanut Allergies in Children--A Review. Clinical Pediatrics, 48(7), 709-714. http://dx.doi.org/10.1177/0009922808330782
