INTRODUCTION   Portugal is the European country with the second highest consumption of seafood, namely shellfish, which includes both crustaceans and

molluscs1. Adverse reactions to shellfish are common in adults and can have similar manifestations in both IgE and non-IgE mediated reactions.  

CONCLUSIONS      Shellfish adverse reactions are a frequent cause of referral for food allergy study, mainly in adults. In our population, risk factors for

IgE mediated allergy were immediate onset of symptoms and severity of the reactions. Other factors, like dust mite sensitization, did not distinguish IgE

mediated allergy, so cross-sensitization may not be inferred. A proper diagnostic work-up is required to confirm cross-reactivity between crustaceans

and molluscs. Awareness should be increased for unnecessary avoidance of other seafood.  

Prevalence  and  Clinical  Presenta8on  of  Shellfish  Adverse  Reac8ons  

4  years  retrospec,ve  study  in  a  Food  Allergy  Unit    Diana  Silva1,2,  Mariana  Couto1,2,  Natacha  Santos  1,  Ana  Margarida  Pereira  1,  José  Luís  Plácido  1,  Alice  Coimbra  1    

1  –  Serviço  Imunoalergologia,  Hospital  São  João,  EPE  -­‐  Porto,  Portugal;  2-­‐  Department  of  Immunology,  Faculty  of  Medicine,  University  of  Porto,  Porto,  Portugal  

22%  

17%  

8%  

8%  6%  

4%  

4%  

4%  

4%  

Prevalence of patients that

reported reactions to shellfish

was 35% (n=79).

30% (n=24) were IgE mediated

Table 1. Demographic and clinical characteristics of all patients (n=79) with reported shellfish adverse reactions (Data is presented as n(%) except if otherwise indicated)

Nº  274  

AIM    To assess the prevalence and clinical characteristics of shellfish adverse reactions among patients with suspected food allergy referred to the Food Allergy Unit of

Centro Hospitalar de São João.

In relation to this presentation, I declare that there are no conflicts of interest.

METHODS    Retrospective, cross-sectional analysis of the clinical files of all patients referred to our

Food Allergy Unit due to suspected food allergic reactions between Jan/2009 and Oct/2012. Suspected

clinical cross reactivity with shellfish, dust mite sensitization, and co-sensitization to other seafood was

studied. Patients who did not complete the study were also characterized

6%

76%

18%

Molluscs

Crustaceans

Molluscs and Crustaceans

Total

IgE

mediated

24(30)

Other

adverse

reactions

31(39)

Incomplete

study

24(30)

p

Age, years (median[IQR]) 31[26;44] 37 [28;50] 33 [25;44] 29 [17;35] 0.405*

Female 61(77) 20(83) 26(84) 15(63) 0.120#

Atopy 57(73) 19(17) 20(65) 18(75) 0.698#

Asthma 28(35) 12(33) 10(32) 6(25) 0.442#

Rhinitis 42(53) 15(63) 14(55) 13(46) 0.422#

HDM sensitization 46(58) 18(75) 17(55) 11(24) 0.109#

Reported symptoms (shellfish) p†

Anaphylaxis 27(34) 15(63) 5(16) 7(29) <0.001#

Muco-cutaneous 45(57) 7(29) 25(81) 13(54) <0.001#

Other1 7(9) 2(8) 1(3) 4(17) 0.403#

Age of onset of symptoms (median[IQR]) 24[15;37] 25[15;37] 28[18;40] 21[13;27] 0.871*

Onset of symptoms after ingestion

<1h 22(59) 13(54) 9(29) 10(42) 0.001#

>1h 15(41) 1(4) 14(45) 5(21) 0.001# IQR, Interquartile Range; HDM- house dust mite * Mann Whitney test; #Chi-square test 1- Other manifestations include 5 with gastro-intestinal symptoms only and 2 with only respiratory symptoms †- p value reported was calculated having in consideration the difference between IgE mediated and other adverse reactions

Reactions

Classification IgE mediated: All with evidence of IgE sensitization to the suspected food AND (history of an anaphylaxis OR clinically suggestive reaction confirmed by an OFC)

Other adverse reactions: Without any evidence of IgE sensitization AND (history of an anaphylaxis OR clinically suggestive reaction with negative OFC)

RESULTS   Figure 2 Reported and confirmed clinical cross-reactivity and/or co-sensitization between seafood. (Data includes a total number of 109 reactions to seafood in a total of 79 patients that reported reactions to shellfish)

Crustaceans (n= 74)

Fish (n=16)

Molluscs (n=19)

14(18%)

5 (6%)

7(9%)

14(18%)

5 confirmed 1 confirmed

1 confirmed

Figure 2. Odds Ratio and 95%CI of having an IgE mediated allergy (univariate analysis)

REFERENCES 1. Lopata AL, O'Hehir RE, Lehrer SB; Shellfish allergy; Clin Exp Allergy. 2010 Jun;40(6):850-8. doi: 10.1111/j.1365-2222.2010.03513.x. Epub 2010 Apr 19.

Figure 1 Reported reactions to shellfish