Silva D, Couto M, Santos N, Pereira AM, Plácido JL, Coimbra A. Prevalence and clinical presentation of shellfish adverse reaction: 4 years retrospective study in a food allergy unit. Allergy 2013;68(Suppl.97):136.

1. 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