Review article Shellfish allergy - an Asia-Pacific perspective 1 1 1 2 Alison Joanne Lee, Irvin Gerez, Lynette Pei-Chi Shek and Bee Wah Lee Summary Conclusion: Shellfish allergy is common in the Background and Objective: Shellfish forms a Asia Pacific. More research including food common food source in the Asia-Pacific and is challenge-proven subjects are required to also growing in the West. This review aims to establish the true prevalence, as well as to summarize the current literature on the understand clinical cross reactivity and epidemiology and research on shellfish allergy variations in clinical features. (Asian Pac J Allergy with particular focus on studies emerging from Immunol 2012;30:3-10) the Asia-Pacific region. Key words: Shellfish allergy, Prawn allergy, Shrimp Data Sources: A PubMed search using search allergy, Food allergy, Anaphylaxis, Tropomyosin, strategies “Shellfish AND Allergy”, “Shellfish Allergy Asia”, and “Shellfish AND anaphylaxis” Allergens, Asia was made. In all, 244 articles written in English were reviewed. Introduction Shellfish, which include crustaceans and Results: Shellfish allergy in the Asia-Pacific molluscs, is one of the most common causes of food ranks among the highest in the world and is the allergy in the world in both adults and children, and most common cause of food-induced anaphylaxis. it has been demonstrated to be one of the top Shellfish are classified into molluscs and ranking causes of food allergy in children in the arthropods. Of the arthropods, the crustaceans Asia-Pacific.1-3 In addition, shellfish allergy usually in particular Penaeid prawns are the most persists, is one of the leading causes of food-induced common cause of allergy and are therefore most anaphylaxis, and has been implicated as the most extensively studied. Several classes of allergens frequent food type to result in an emergency have been identified. The tropomyosins (class 1 department consult in those aged above 6 years allergens) are the best defined. Despite the old.4,5 establishment of molecular homology and It has particular impact in the Asia-Pacific region allergenic cross reactivity between allergens of where the consumption as well as the supply of the same class, clinical cross-reactivity is more seafood is the highest in the world. Shellfish variable between patients and less clearly comprises one quarter of this supply.6 China and defined. There are two relatively unique clinical Japan are among the top three consumers (Northern manifestations of IgE-mediated prawn allergy: America as second), with many other Asian (1) isolated oral allergy symptoms; and (2) wide countries such as India, Indonesia, Philippines, spectrum of severity and sometimes even within Korean Republic, Vietnam, Bangladesh and the same individual. Thailand also listed among the top ten consumers of seafood worldwide. This review aims to outline the epidemiology and From the 1. Department of Paediatrics, University Children’s highlight the major and clinically cross-reactive Medical Institute, National University Health System, allergens in shellfish allergy, with particular focus Singapore on the Asia-Pacific region. A PubMed search 2. Department of Paediatrics, National University of Singapore strategy using the terms “Shellfish AND Allergy”, Corresponding author: Bee Wah Lee “Shellfish Allergy Asia”, and “Shellfish AND E-mail: [email protected] anaphylaxis” were performed. This search resulted Submitted date: 2/2/2012 in 285 articles. This review was limited to ‘English’ articles, resulting in 244 articles, of which 58 were review articles, and 29 were original articles from the Asia Pacific. 3 Downloaded from http://apjai.digitaljournals.org. For personal use only. No other uses without permission. Asian Pac J Allergy Immunol 2012;30:3-10 Classification of Shellfish Table 1. Classification of Shellfish, Fish and Arthropod There is a perception amongst clinicians and lay species persons that shellfish allergens are highly cross Common Phyla Subphyla Class Common reactive and that clinical allergy to a particular reference Name shellfish would often necessitate avoidance of most “Shellfish” Mollusca Gastropoda Abalone, shellfish. It is therefore worthwhile clarifying this (inverte- snails brates) (escargot), notion as unnecessary avoidance may be advised. welk Clinicians managing shellfish allergy should also be Bivalvia Mussels, conversant with the classification of edible shellfish, oysters, clams, as well as the described allergens that are known to scallop, be cross reactive. cockle Cephalopoda Squids Edible seafood is classified into 3 main phyla – (calamari), Mollusca, Arthropoda (crustaceans) and Chordata octopus, cuttlefish (fish). The term ‘Shellfish’ generally refers to the Arthropoda Crustacea Malacostraca Shrimps two invertebrate groups - the molluscs and (caridea), crustaceans, which are further sub-categorised prawns (penaeidae), (Table 1). The chordata phylum includes finned fish, crabs, with the major class being Osteichthyes. However lobsters, this group contains very different allergens from crayfish 7 Arthropoda Chelicerates Arachnida Spiders, shellfish and will not be included in this review. mites Within the phylum crustaceans, ‘prawns’ and (including house dust ‘shrimps’ are terms often used interchangeably. A mites) ‘shrimp’ in the USA is known as a ‘prawn’ in Xiphosura Horseshoe Australia, and among some English-speaking crab Hexapoda Insecta Cockroaches, regions in Asia. The modern day carcinologists wasps, bees, (crustacean experts) also do not differentiate butterflies Myriapoda Centipedes, between these terms (personal communication P Ng, millipedes National University of Singapore). However, the “Fish” Chordata Osteichthyes Salmon, generic use of ‘prawns and shrimp’ in medical (main class) tuna, cod, grouper, literature is confusing because it may refer to snapper, tuna species belonging to separate families within the taxonomy tree, and it is important to address these 8 Anatomically, the Penaeid prawns and Caridean differences. shrimps differ in the way the segments overlap, leg Prawns and shrimps belong to the Decapoda (‘10 proportions and how they brood their eggs.8 The footed’ in Latin), which forms one of the largest Caridean shrimps are often inedible due to their crustacean groups (order of the malacostraca). This small size, but could come commercially packed in group also includes crabs, crayfish and lobsters. cans or preserved-dry packets, which are used for Decapoda almost always have 5 pairs of legs on the food flavouring in Asian cooking. There are main thoracic body and 5 pairs of swimmerets on however, exceptions, and Caridean shrimps may the abdomen or tail. Within the class Decapoda, the also be large in size. For example, freshwater commonly used terms, ‘prawns and/or shrimps’ Caridean shrimp (Macrobrachium Rosenbergii) are usually refer to the group, Penaeidae. However, quite large and can grow to over 30cm in length. there exists another Decapoda family, the Caridea, This freshwater Caridean shrimp is frequently eaten which are also referred to as ‘shrimp’, and it is and popular as a food in South East Asia. Of important to establish that Penaeidae and Caridea interest are the recent reports of mono-allergy to are different and belong to separate taxonomical freshwater shrimps, Macrobrachium Rosenbergii crustacean families. Penaeids are usually larger and and Macrobrachium Lanchesteri, in the Thai of greater commercial impact, and are the most population, without concomitant prawn allergy.9,10 commonly implicated food in shellfish allergy. There are several thousand species of prawns and Hence, in this review, the term ‘prawn’ will refer to shrimp. The most common prawns eaten in the Penaeids and the term ‘shrimp’ refers to a Singapore and Asia are the black tiger prawns different group, Carideans. (Penaeus monodon), the white leg pacific prawn 4 Downloaded from http://apjai.digitaljournals.org. For personal use only. No other uses without permission. Shellfish allergy Table 2. Shellfish Allergens and Allergen Nomenclature# Myosin Sarcoplasmic Arginine Tropomysin Light calcium-binding Others Kinase Challenge protein Crustaceans Prawn, Black tiger (Penaeus monodon) Pen m 1 Pen m 2 Pen m 4 Prawn, Brown (Penaeus aztecus) Pen a 1 Prawn, White leg pacific (Litopenaeus vannamei) Lit v 1 Lit v 2 Lit v 3 Prawn, Fleshy (Fenneropanaeus chinensis) Fen c 1 Fen c 2 Prawn, Tiger (Marsupenaeus japonicus) Mar j 1 Mar j 2 Mar j 4 Prawn, Banana (Fenneropenaeus merguiensis) Fen me 1 Prawn, fleshy (Penaeus orientalis) Pena o 1 Prawn, sand (Metapenaeus ensis) Met e 1 Shrimp, Giant fresh water (machrobrachium Mac ro 1 Mac ro hemocyanin rosenbergii) Crab, Mud (Scylla paramamosain) Scy pa 1 Scy pa 2 Crab, Snow (Chionoecetes opilio) Chi o 1 Chi o 2 Chi o 4 Krill, Antartic (Euphasia superba) Eup s 1 Krill, Pacific (Euphasia pacifica) Eup p 1 Lobster, American (Homarus americanus) Hom a 1 Hom a 3 Lobeter, Rock (Jasus Lalandii) Jas la 1 Lobster, Spiny (Panulirus stimpsoni) Pan s 1 Molluscs Abalone ( Haliotis discus) Hal d 1 Abalone ( Haliotis midae ) Hal m 2 Abalone ( Haliotis rufescens ) Hal r 1 Common whelk ( Buccinum undatum) Buc u 1 Mussel, Tropical Green (Perna viridis) Per v 1 Octopus, Common (Octopus vulgaris) Oct v 1 Oyster, Pacific (Crassostrea gigas) Cra g 1 Clam, Razor (Ensis macha) Ens m 1 Cockles, Japanese (Venerupis philippinarum) Ven ph 1 Scallop, Japanese (Chlamys Chlamys nipponensis) Chl n 1 Scallop, Giant (Patinopecten yesooensis) Pat y 1 # Allergen nomenclature