Epidemiology and clinical presentations of seafood allergy in the Asia Pacific

Le, Thi Kieu Thu (2019) Epidemiology and clinical presentations of seafood allergy in the Asia Pacific. PhD thesis, James Cook University.

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Food allergy is defined as an adverse response of a human's immune system triggered by food antigens. Food allergy is not a new abnormal health phenomenon, but was observed and documented thousands of years ago. However, recently, food allergy has become a substantial and severe health concern in many populations worldwide with a dramatically increasing number of hospital admissions due to food-related allergic reactions and food-induced anaphylaxis. Substantial investigations have been conducted, mostly in developed countries in Europe, America, and Oceania, to estimate food allergy prevalence and define its possible negative impacts on population health. Despite enormous research efforts and advances in the field of food allergy, its pathogenesis and the disparities in the patterns of food allergens across regions are not fully understood. This thesis aims to investigate the prevalence of food allergy and its risk factors in Vietnam. Further investigations on the clinical presentations and immunological profiles of seafood allergic subjects in Vietnam and Australia were carried out in an effort to compare and identify crucial determinants of seafood allergy, which may enable the development of immunotherapy and improve allergy diagnosis.

A comprehensive review of the contemporary understanding and studies of food allergy worldwide is presented in Chapter 1 of this thesis. The current advances in food allergy diagnosis and its pitfalls are discussed. An overview of seafood consumption and seafood safety, along with current gaps and needs in seafood allergy management in Vietnam, are also addressed.

Food allergy is reported to affect up to 10% of children and 5% of adults in the developed world, with this high prevalence often referred to as an emerging allergy epidemic. Given that these cases of food allergy are often assumed to be the consequence of an industrialized lifestyle, my research question is whether or not there has also been a food allergy epidemic in developing economies. Do people in other parts of the world suffer from allergy to the same type of foods as those already characterized in Western societies? These are the rationales for me to conduct the first population-based survey of food allergy in Vietnam; to evaluate the current situation of food allergy in this developing country. A survey of Vietnamese preschool children is presented in Chapter 2 and a survey of Vietnamese adults is provided in Chapter 3 of this thesis. These studies estimate the frequency of doctor-diagnosed food allergy in preschool children and adults in Vietnam to be 6.7% and 4.6%, respectively. Vietnamese subpopulations have comparatively high incidence rates of food allergy compared to what has been reported in previous studies from Europe or America. This Vietnamese population showed a stark difference in the allergy-triggering food patterns exhibited, with adominance of crustacean, mollusk and fish allergy occurring in both children and adults. Allergy to beef was also identified; this being the first time this new food allergy type has been recognized in Asia. The variation in types of food allergy present was addressed across geographical regions in Vietnam. Food allergy associated risk factors were identified, underlying the interrelations of genetic and environmental determinants to food allergy incidence. These findings provide insights into the current food allergy situation in Vietnam and addresses the need for more effective allergy management initiatives in this country.

Food allergy studies remain limited in many parts of the world; thus, leading to a lack of food allergy management policies and medical readiness for appropriate interventions. This raises concerns about potential impacts of food allergy on population health. It is assumed that the paucity of food allergy epidemiologic data is due to the high financial costs of organizing conventional epidemiological studies of food allergy. Chapter 4 of this thesis sought out and validated an alternative method for the traditional population-based survey, with the aid of internet tools. By comparing the study outcomes from two consistent and independent food allergy population-based surveys, using two different modes: paper-based and web-based surveys, we confirmed the applicability of web-based surveys as a reliable and low-cost alternative for future epidemiological studies, especially in developing countries.

Self-administered questionnaire surveys have been a major tool in estimating food allergy prevalence worldwide. A thorough clinical history is important in the diagnosis of food allergy, however misconceptions from the survey respondents regarding true food allergy and other types of food hyperactivity are likely. The discovery of Immunoglobulin E (IgE) antibody as the biomarker of type I food allergy subsequently plays a crucial role in the current diagnosis of food allergy. Acknowledging this importance of applying multiple in vitro and in vivo diagnostics in food allergy, an investigation on the serum IgE reactivity among people with a history of seafood allergy to commonly consumed crustacean, mollusk and fish species was conducted. The analysis of the immunological profiles of people with seafood allergy in Vietnam is described in Chapter 5 of this thesis. Generally, seafood allergic participants from Vietnam showed a diverse pattern of serum specific IgE reactivity to different crustacean and mollusk species. Multiple cross-reactivities between crustacean allergic patients and allergens from house dust mite, cockroach and mealworm were revealed. This finding once again confirmed the enormous contribution of environmental factors to the incidence of food allergy and was in line with the findings from the population-based surveys in the previous chapters.

Besides environmental factors, ethnicity and eating habits may play a role in developing a food allergy. The latter includes the availability of a food commodity in a region and local food preparation practices. A similar investigation on seafood allergy conducted in Australian adults was presented in Chapter 6. Participants were invited to an interview with food allergy specialists to collect clinical history. Participants' sera were collected and screened for the serum specific IgE reactivity in the laboratory to a panel of typical local crustacean, mollusk and fish species. In general, seafood allergic participants from Australia demonstrated diversified species-specific IgE reactivity to crustacean, mollusk and fish species. Prawns appeared to be the most allergenic crustacean. Mite exposure seems to be common among participants with a history of shellfish allergy. Shellfish allergic subjects reacted to fish allergens and vice versa. Besides tropomyosin, the contribution of other allergens is possible and needs further investigation.

Following on from the findings in the previous chapters, Chapter 7 of this thesis focuses on the identification and characterization of putative crustacean allergens utilizing the participants from Vietnam and Australia. Crustacean protein extracts were separated by their molecular weight (SDS-PAGE), and immunoblotting techniques were applied to identify the participants' specific IgE recognition pattern to the different crustacean proteins. The protein bands that displayed IgE reactivity were cut out and digested with trypsin for the identification of the allergen by mass spectrometry (Bio21, Melbourne, Australia). The mass spectral interpretation of the proteins was performed by uploading the data to Mascot (Matrix Science, London, UK). The crustacean allergen profiles among the two populations were compared and discussed.

By conducting a consistent investigation of seafood allergy in two distinct populations, the investigator was able to characterize and compare the phenotypes and allergen reactivity profiles between the two representative populations. This study provided evidence into the clinical characteristics of seafood allergy, giving crucial insights for the development of more reliable food allergy diagnostics for the local populations. All the outcomes, as well as future directions, are discussed in Chapter 8.

In summary, this thesis provides an extensive analysis of food allergy and seafood allergy in Vietnam. Seafood-including crustacean, mollusk, and fish-is the most common type of allergy-triggering food in Vietnam. Regarding allergy risk factors, both child and adult participants with a family history of food allergy were significantly more prone to developing food allergy. The study demonstrated and compared distinct species-specific IgE binding patterns among seafood allergic patients in Vietnam and Australia. The cross-reactivity of seafood allergic participants to insect and indoor allergens was revealed. The findings from this thesis provide an important contribution towards the current gaps and needs in the national-scale management of food allergy in Vietnam, and initiate the development of advanced, more precise diagnosis of seafood allergy, not just in Vietnam but also in Asia-Pacific regions in general. Several directions for future work involve following-up investigations on other major food allergies that were identified from the population-based survey (i.e. red meat allergy), investigating food allergy prevalence in other subpopulations (e.g. infants, adolescents) in Vietnam to determine the overall food allergy frequency and the variation of food allergy over the life course. The clinical and immunological data from the seafood allergy study in this thesis is paving the groundwork for the future development of region-specific in vitro diagnostic tests.

Item ID: 64139
Item Type: Thesis (PhD)
Keywords: adults, children, crustacean allergy, Epidemiological survey, fish allergy, food allergy, IgE antibody, mollusc allergy, Paper-based survey, parvalbumin, Population-based survey, prevalence, seafood allergy, tropomyosin, Vietnam, Web-based survey
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Copyright Information: Copyright © 2019 Thi Kieu Thu Le.
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Three publications arising from this thesis are stored in ResearchOnline@JCU, at the time of processing. Please see the Related URLs. The publications are:

Chapter 1: Ruethers, Thimo, Taki, Aya C., Johnston, Elecia B., Nugraha, Roni, Le, Thu T.K., Kalic, Tanja, McLean, Thomas R., Kamath, Sandip D., and Lopata, Andreas L. (2018) Seafood allergy: a comprehensive review of fish and shellfish allergens. Molecular Immunology, 100. pp. 28-57.

Chapter 2: Le, Thu T.K., Nguyen, Duy H., Vu, An T.L., Ruethers, Thimo, Taki, Aya C., and Lopata, Andreas L. (2019) A cross-sectional, population-based study on the prevalence of food allergies among children in two different socio-economic regions of Vietnam. Pediatric Allergy and Immunology, 30 (3). pp. 348-355.

Chapter 3: Le, Thu T.K., Tran, Thuy T.B., Ho, Huong T.M., Vu, An T.L., McBryde, Emma, and Lopata, Andreas L. (2020) The predominance of seafood allergy in Vietnamese adults: results from the first population-based questionnaire survey. World Allergy Organization Journal, 13 (3).

Chapter 4: Le, Thi T.K., Tran, Thuy T.B., Ho, Huong T.M., Vu, An T.L., and Lopata, Andreas L. (2018) Prevalence of food allergy in Vietnam: comparison of web-based with traditional paper-based survey. World Allergy Organization Journal, 11. 16.

Date Deposited: 25 Aug 2020 22:28
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1117 Public Health and Health Services > 111706 Epidemiology @ 35%
11 MEDICAL AND HEALTH SCIENCES > 1107 Immunology > 110701 Allergy @ 35%
11 MEDICAL AND HEALTH SCIENCES > 1101 Medical Biochemistry and Metabolomics > 110106 Medical Biochemistry: Proteins and Peptides (incl Medical Proteomics) @ 30%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920108 Immune System and Allergy @ 100%
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