Molluscan shellfish allergies

The importance of molluscan shellfish allergy is increasingly recognized. The European Union recently added molluscan shellfish to the list of most commonly allergenic foods in Europe (EESA, 2006). Although not knovm... 

Ranee et al. (2005) conducted a questionnaire-based survey of food allergy in 2716 school children in France. Four cases of molluscan shellfish allergy were reported to mussels, snails, and oysters among this group. Thus, the self-reported prevalence of molluscan shellfish allergy in this population of children was 0.15%. 

These two surveys are in reasonably good agreement regarding prevalence estimates for molluscan shellfish allergy. That is especially true since all the ages were included in the surveyed population of Sicherer et al. (2004) while only children were involved in the French survey (Ranee et ah, 2005). Hypothetically, sensitization to molluscan shellfish might develop later in life than for other foods because of the infrequent consumption pattern. 

The number of sfudies estimating the comparative prevalence of molluscan shellfish allergy is limited. The frequency of consumption of molluscan shellfish mighf be higher in some of the locales where such studies have been performed. Clearly, more comparative clinical data would be helpful. However, the molluscan shellfish certainly seem to be a comparatively common allergenic food in some locales and among some populations. 

Molluscan shellfish allergy has been described in the medical literature to virtually all of the commonly ingested types of molluscan shellfish. The following sections will summarize published reports of allergic reactions to the major categories of edible molluscan shellfish — gastropods, bivalves, and cephalopoda. 

H. Food-dependent, exercise-induced molluscan shellfish allergy... 

Clearly, some individuals with molluscan shellfish allergy are reactive to all species of molluscan shellfish. Cross-reactivity has been established by clinical history, challenge trials (in a few instances), skin prick testing, and IgE-binding studies. Most clinical studies of cross-reactivity have been limited to a few species often within one class of molluscan shellfish. However, the totality of the evidence indicates that individuals with documented reactivity to one molluscan species and evidence of IgE against that species should be counseled to avoid other molluscan shellfish species. This recommendation is especially prudent for the individual classes of molluscan shellfish gastropods, bivalves, and cephalopods. 

Cross-reactivity between molluscan and crustacean shellfish species also occurs rafher frequently. Since tropomyosin is the major allergen in both molluscan and crustacean shellfish, fhe frequency of cross-reactions is not surprising. Allergy to crustacean shellfish is more frequenfly diagnosed than molluscan shellfish allergy (Hefle et ah, 2007). Many of fhese individuals may be at risk of reactions fo molluscan shellfish also. Appropriately, most individuals with either molluscan or crustacean shellfish allergy are advised to avoid all shellfish. 

The only proven therapy for molluscan shellfish allergy is strict dietary avoidance. Problems may arise with avoidance diets when clam is present due to mislabeling or to cross-contact during food processing (Taylor and Hefle, 2005 Taylor et ah, 1986,1999). The food industry typically develops allergen control programs to prevent the occurrence of undeclared allergenic residues in other foods (Taylor et ah, 2006). The industry often uses... 

Taylor, S.L. 2008. Molluscan shellfish allergy. Advances in Food and Nutrition Research 54 139-177. 

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