Shellfish allergy – Symptoms and causes

Overview

Shellfish allergy is an abnormal response by the body’s immune system to proteins in certain marine animals. Marine animals in the shellfish category include crustaceans and mollusks, such as shrimp, crab, lobster, squid, oysters, scallops and others.

Some people with shellfish allergy react to all shellfish; others react to only certain kinds. Reactions range from mild symptoms — such as hives or a stuffy nose — to severe and even life-threatening.

If you think you have a shellfish allergy, talk to your doctor. Tests can help confirm the allergy so you can take steps to avoid future reactions.

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Symptoms

Shellfish allergy symptoms generally develop within minutes to an hour of eating shellfish. They may include:

• Hives, itching or eczema (atopic dermatitis)
• Swelling of the lips, face, tongue and throat, or other parts of the body
• Wheezing, nasal congestion or trouble breathing
• Abdominal pain, diarrhea, nausea or vomiting
• Dizziness, lightheadedness or fainting

Allergies can cause a severe, potentially life-threatening reaction known as anaphylaxis. An anaphylactic reaction to shellfish or anything else is a medical emergency that requires treatment with an epinephrine (adrenaline) injection and a trip to the emergency room.

Signs and symptoms of anaphylaxis include:

• A swollen throat or a lump in your throat (airway constriction) that makes it difficult for you to breathe
• Shock, with a severe drop in your blood pressure
• Dizziness, lightheadedness or loss of consciousness

When to see a doctor

Seek emergency treatment if you develop signs or symptoms of anaphylaxis.

See a doctor or allergy specialist if you have food allergy symptoms shortly after eating.

Causes

All food allergies are caused by an immune system overreaction. In shellfish allergy, your immune system mistakenly identifies a certain protein in shellfish as harmful, triggering the production of antibodies to the shellfish protein (allergen). The next time you come in contact with the allergen, your immune system releases histamine and other chemicals that cause allergy symptoms.

Types of shellfish

There are several types of shellfish, each containing different proteins:

• Crustaceans include crabs, lobster, crayfish, shrimp and prawn.
• Mollusks include squid, snails, clams, oysters and scallops.

Some people are allergic to only one type of shellfish but can eat others. Other people with shellfish allergy must avoid all shellfish.

Risk factors

You’re at increased risk of developing a shellfish allergy if allergies of any type are common in your family.

Though people of any age can develop a shellfish allergy, it’s more common in adults. Among adults, shellfish allergy is more common in women. Among children, shellfish allergy is more common in boys.

Complications

In severe cases, shellfish allergy can lead to anaphylaxis, a dangerous allergic reaction marked by a swollen throat (airway constriction), rapid pulse, shock, and dizziness or lightheadedness. Anaphylaxis can be life-threatening.

When you have shellfish allergy, you may be at increased risk of anaphylaxis if:

• You have asthma
• You have allergic reactions to very small amounts of shellfish (extreme sensitivity)
• You have a history of food-induced anaphylaxis

Anaphylaxis can be treated with an emergency injection of epinephrine (adrenaline). If you are at risk of having a severe allergic reaction to shellfish, you always should carry injectable epinephrine (EpiPen, Adrenaclick, others).

Prevention

If you have a shellfish allergy, the only way to avoid an allergic reaction is to avoid all shellfish and products that contain shellfish. Even trace amounts of shellfish can cause a severe reaction in some people.

Avoiding shellfish

• Be cautious when dining out. When dining at restaurants, always check to make sure that the pan, oil or utensils used for shellfish aren’t also used to prepare other foods, creating cross-contamination. It might be necessary to avoid eating at seafood restaurants, where there’s a high risk of cross-contamination.

• Read labels. Cross-contamination can occur in stores where other food is processed or displayed near shellfish and during manufacturing. Read food labels carefully.

  Shellfish is rarely a hidden ingredient, but it may be in fish stock or seafood flavoring. Companies are required to label any product that contains shellfish or other foods that often cause allergic reactions, but the regulations don’t apply to mollusks, such as clams, oysters and scallops.

• Keep your distance. You may need to completely avoid places where shellfish are prepared or processed. Some people react after touching shellfish or inhaling steam from cooking shellfish.

If you have a shellfish allergy, talk with your doctor about carrying emergency epinephrine. Consider wearing a medical alert bracelet or necklace that lets others know you have a food allergy.

One thing you don’t need to worry about is if you’ll also be allergic to iodine or radiocontrast dye that’s used in some imaging tests. Even though shellfish contain small amounts of iodine, shellfish allergy is unrelated to the reactions some people have to radiocontrast material or iodine.

Shellfish Allergies – Asthma & Allergies Center

Shrimp scampi, baked lobster, and oysters on the half-shell can cause serious illness if you have a shellfish allergy. Here’s what you need to know.

“Shellfish allergy is the most common food allergy in adults,” says Anna Feldweg, MD, a clinical instructor of medicine at Harvard Medical School and attending physician in allergy and immunology at Brigham and Women’s Hospital in Boston. Triggered by eating shrimp, lobster, crab, or crayfish, this type of allergy can lead to a serious illness or even death, so it’s important to get a proper diagnosis and learn some precautions.

What Causes Shellfish Allergies?

“Shrimp is the leading culprit [of shellfish allergy] in this country,” says Dr. Feldweg. But, she adds, in other countries where people tend to eat different types of shellfish, the leading cause can be different.

Shellfish allergies are most commonly caused by crustaceans such as shrimp, lobster, crab, and crayfish. But people have also been known to have a shellfish allergy related to bivalves such as oysters, clams, and mussels, as well as snails, squid, and octopus.

Shellfish Allergy Risk Factors

It is not known for certain why some individuals get shellfish allergies and others do not. However, your risk of having a food allergy increases if your family has allergic illnesses such as asthma or allergic rhinitis. Your chances of having a food allergy is higher if you have two allergic parents than if you only have one.

Shellfish Allergy Symptoms

In people with a shellfish allergy, “the reactions can be very severe, and they are also unpredictable,” says Feldweg. “Someone may get hives one time they eat shrimp. If they are exposed to it again, they can have a much more severe reaction,” she adds.

Symptoms of a shellfish allergy usually occur within a few minutes to an hour of ingestion and may include:

• Stomach or bowel symptoms (vomiting, diarrhea)
• Itching
• Flushing
• Hives (raised patches on the skin that are extremely itchy)
• Swelling of the lips, face, and/or throat
• Wheezing
• Low blood pressure symptoms (dizziness, lightheadedness)

In susceptible people, these symptoms occur because the body’s immune system has produced a type of IgE (immunoglobulin E), which is an allergic antibody that recognizes shellfish and reacts to it as if it were a dangerous threat. This antibody attaches to your body’s allergy cells, called mast cells and basophils. When you eat the shellfish again, the IgE on the cells recognizes the shellfish proteins, and causes the mast cells and basophils to release chemicals that result in itching, hives, swelling, and other symptoms of an allergic reaction.

Shellfish Allergy Prevention

For people who have a shellfish allergy, “we usually suggest that they avoid all shellfish,” says Feldweg. However, you can be allergic to one type of shellfish and not another, and you should work closely with an allergist you are comfortable with to determine what types of foods you should avoid, and what types you may be able to eat.

Most people who have a shellfish allergy are able to eat fish with fins, says Feldweg, who commonly advises her patients to cook their seafood meals at home, so that they can control what is going into their meals.

Feldweg said that since seafood restaurants almost always use shellfish-based broths and other ingredients that contain shellfish in all of their dishes, people with a shellfish allergy should avoid eating at seafood restaurants.

And people with a shellfish allergy should carry an injectable form of epinephrine, such as an EpiPen, with them at all time.

Shellfish Allergy | Causes, Symptoms & Treatment

Once a shellfish allergy is identified, the best management is to avoid the food. You need to carefully check ingredient labels of food products. You should learn other names for the foods you need to avoid to be sure not to eat them.

You must be extra-careful when you eat out. Waiters (and sometimes the kitchen staff) may not always know every dish’s ingredient list. Vapors may carry small particles of shellfish protein, so being close to where food is being prepared can potentially cause a dangerous reaction in sensitive individuals.

Fortunately, shellfish is an ingredient that is rarely “hidden” in foods. Shellfish may be found in fish stock, seafood flavoring (for example, crab extract), sushi and surimi. Crustacean shellfish is one of the eight allergens that fall under the labeling requirements of the Food Allergen Labeling and Consumer Protection Act of 2004. This means that manufacturers of packaged food items sold in the United States and containing crustacean shellfish or a crustacean shellfish-based ingredient must state, in clear language, the presence of crustacean shellfish in the product. (Note: Those regulations apply only to crustacean shellfish, such as shrimp, lobster and crab, and not to mollusks, such as oysters, scallops and clams.)

Anyone with a food allergy must understand how to read ingredient labels and practice avoidance measures. Your allergist can direct you to helpful resources, such as special cookbooks, patient support groups and registered dietitians, who can help you plan your meals.

Many people with food allergies wonder if their condition is permanent. There is no clear-cut answer. Over time, allergies to milk, eggs and soy may disappear. Allergies to peanuts, tree nuts, fish and shellfish typically last a lifetime. About one-third of children and adults with a food allergy eventually outgrow the allergy. But rates of naturally outgrowing food allergies will vary depending on the specific food allergen and the person.

Managing a severe food reaction with epinephrine

Shellfish is among the most common food allergens. But all food allergies can be dangerous.

Epinephrine is the first-line treatment for anaphylaxis, a severe whole-body allergic reaction that causes symptoms, including tightening of the airway. Anaphylaxis can occur within seconds or minutes of exposure to the allergen, can worsen quickly, and can be deadly.

Once a food allergy diagnosis is made, your allergist likely will prescribe an epinephrine auto-injector and teach you how to use it. Check the expiration date of your auto-injector, note the expiration date on your calendar and ask your pharmacy about reminder services for prescription renewals.

Be sure to have two doses available, as the severe reaction may recur. Epinephrine should be used immediately if you experience severe symptoms such as shortness of breath, repetitive coughing, weak pulse, generalized hives, tightness in the throat, trouble breathing or swallowing, or a combination of symptoms from different body areas such as hives, rashes or swelling on the skin coupled with vomiting, diarrhea or abdominal pain. Repeated doses of epinephrine may be necessary.

If you are uncertain whether a reaction requires epinephrine, use it right away, because the benefits of epinephrine far outweigh the risk that a dose may not have been necessary.

Common side effects of epinephrine may include temporary anxiety, restlessness, dizziness and shakiness. Rarely, the medication can lead to an abnormal heart rate or rhythm, a heart attack, a sharp increase in blood pressure and fluid buildup in the lungs, but these adverse effects are generally caused by errors in dosing which is unlikely to occur with use of epinephrine autoinjectors. Some people with certain pre-existing conditions might be at higher risk for adverse effects and should speak to their allergist about epinephrine use.

Your allergist will provide you with a written emergency treatment plan that outlines which medications should be administered and when (note that between 10 and 20 percent of life-threatening severe allergic reactions have no skin symptoms). Be sure you understand how to properly and promptly use an epinephrine auto-injector.

Once you have used your epinephrine auto-injector, immediately call 911 and tell the dispatcher that you used epinephrine and that more may be needed from the emergency responders.

Other medications, such as antihistamine and corticosteroids, may be prescribed to treat mild symptoms of a food allergy, but it is important to note that there is no substitute for epinephrine — this is the only medication that can reverse the life-threatening symptoms of anaphylaxis.

Managing shellfish allergies in children

Because shellfish allergy reactions, like other food allergy symptoms, can develop when a child is not with his or her parents, parents need to make sure that their child’s school, day care or other program has a written emergency action plan with instructions on preventing, recognizing and managing these episodes in class and during activities such as sporting events and field trips.

If your child has been prescribed an auto-injector, be sure that you and those responsible for supervising your child understand how to use it.

This page was reviewed and updated as of 2/13/2019.

Not all shellfish “allergy” is allergy!

Abstract

The popularity of shellfish has been increasing worldwide, with a consequent increase in adverse reactions that can be allergic or toxic. The approximate prevalence of shellfish allergy is estimated at 0.5-2.5% of the general population, depending on degree of consumption by age and geographic regions. The manifestations of shellfish allergy vary widely, but it tends to be more severe than most other food allergens.

Tropomyosin is the major allergen and is responsible for cross-reactivity between members of the shellfish family, particularly among the crustacea. Newly described allergens and subtle differences in the structures of tropomyosin between different species of shellfish could account for the discrepancy between in vitro cross-antigenicity and clinical cross-allergenicity. The diagnosis requires a thorough medical history supported by skin testing or measurement of specific IgE level, and confirmed by appropriate oral challenge testing unless the reaction was life-threatening.

Management of shellfish allergy is basically strict elimination, which in highly allergic subjects may include avoidance of touching or smelling and the availability of self-administered epinephrine. Specific immunotherapy is not currently available and requires the development of safe and effective protocols.

Introduction

Seafood consumption has increased in popularity and frequency worldwide. The largest consumer is China, followed by Japan and United States of America. In 2009, Americans ate an average of 15.8 pounds of fish and shellfish per capita, with shrimp being the top choice at 4.1 pounds [1]. The increased production and consumption of seafood has been accompanied by increasing reports of adverse reactions to seafood. Such reactions can be immune-mediated allergic reactions or non-immunologic, with both presenting with similar symptoms.

Prevalence and epidemiology

Shellfish is one of the leading causes of food allergy in adults and is a common cause of food-induced anaphylaxis. In an international survey using a questionnaire administered to 17,280 adults (aged 20-44 years) from 15 countries, symptoms related to seafood were reported to be caused by shrimp in 2.3%, oyster in 2.3%, and fish in 2.2% [2]. In the United States, a telephone survey of 14,948 individuals revealed that 2-3% believed to have seafood allergy: 2.2% to shellfish and 0.6% to fish [3]. Shellfish allergy was much lower in children than in adults (0.5 vs 2.5%). In a decreasing frequency, the causative types of shellfish were shrimp, crab, lobster, clam, oyster and mussel.

The prevalence of shellfish allergy in Asian countries is higher than in western countries [4], and this might reflect the geographic consumption of shellfish. In a study of children residing in Singapore [5], the prevalence of shellfish allergy was more common in native children (4-6 years, 1. 19%; 14-16 years, 5.23%) compared to expatriate children (4-6 years, 0.55%; 14-16 years, 0.96%). Specific shellfish allergy can reflect regional consumption of that particular species.

Only a few studies evaluated the natural history of shellfish allergy, and they seem to indicate that it is long-lasting [6]. In a study of 11 subjects with shrimp hypersensitivity [7], shrimp-specific IgE levels in all subjects were relatively constant during the 24 months of the study and were not affected by shrimp challenge. Another study [8] however, revealed that children with shrimp allergy have higher specific IgE antibody levels, show more intense binding to shrimp peptides, and a greater epitope diversity than in adults, suggesting that sensitization to shrimp might decrease by age.

Classification of shellfish (Figure )

Classification of shellfish.

“Shellfish” and “seafood” are often used by the public interchangeably and with different meanings. “Seafood” is a general term that refers to any edible aquatic animals, whereas “shellfish” refers to those with a shell or shell-like exoskeleton i. e. crustacea and mollusks. Crustacea are classified among arthropods together with arachnids and insects, whereas mollusks include Bivalves, Gastropods and Cephalopods.

Shellfish toxic syndromes (Table )

Table 1

Shellfish toxic syndromes

Shellfish poisoning frequently masquerade as an allergic reaction. Ingestion of contaminated shellfish results in a wide variety of symptoms depending on the concentration of toxins and amount consumed. Five types of shellfish poisoning have been identified [9]. Scombroid poisoning [10] has been linked to fish by the action of bacteria on muscle histidine and production of histamine. To the best of our knowledge, we did not encounter any reports in the English literature on scombroid poisoning from shellfish consumption.

Paralytic shellfish poisoning

Paralytic shellfish poisoning [11] is the best known and it is caused by saxitoxins. It is the most severe, with neurological symptoms predominating. Within 30 minutes of ingestion, the first and most consistent presentation is numbness, tingling or burning of lips, tongue and throat. Paresthesias involve the face and neck and often spread to other parts of the body. Muscular weakness then affects the extremities, and in more severe cases, dysphonia, dysphagia and ataxia occur. Paralysis may occur within 2-12 hours and may persist for as long as 72 hours. Bivalve mollusks such as mussels, clams and oysters assimilate and temporarily store saxitoxins, a complex of neurotoxins produced by dinoflagellates. In the United States, paralytic shellfish poisoning is a problem primarily in the New England states on the East Coast and in Alaska, California and Washington on the West Coast. It has also been reported in Asia, Africa, Europe, Oceania and South America.

Neurotoxic shellfish poisoning

Neurotoxic shellfish poisoning [11] is characterized by both gastrointestinal and neurologic symptoms. It resembles a mild case of paralytic shellfish poisoning but without paralysis. The onset occurs within 3 hours of ingestion of shellfish contaminated with brevetoxins. Symptoms include numbness of lips, tongue and throat which then spread to other parts of the body. Muscular aches, dizziness, reversal of hot and cold temperature sensation occur along with nausea, vomiting, abdominal pain and diarrhea. Karenia brevis is the dinoflagellate that synthesizes brevetoxins, a group of related heat-stable toxins that are responsible for the clinical manifestations of neurotoxic shellfish poisoning. In the United States, the illness is generally associated with the consumption of shellfish harvested along the coast of Gulf of Mexico from Florida to Texas and sporadically along the southern Atlantic coast. K. Brevis blooms are also known as “red tides” because of the red coloration of seawater. Unlike other shellfish toxins, the brevetoxins can aerosolize by surf and wave action along the beach during red tides. These irritant toxin aerosols can cause conjunctival irritation, sneezing and rhinorrhea that resemble an allergic response. Exposure to such toxins in individuals with underlying asthma or chronic obstructive pulmonary disease can lead to shortness of breath, non productive cough and wheezing.

Amnesic shellfish poisoning

Amnesic shellfish poisoning [9] presents initially with vomiting, diarrhea and abdominal cramping within 24 hours after ingestion of shellfish contaminated with domoic acid. In some cases, varying degrees of neurological dysfunction ensues within 48 hours, including confusion, loss of memory and disorientation. The loss of short term memory is unique to this type of shellfish poisoning. Other neurological symptoms are headache, hyporeflexia, hemiparesis, ophthalmoplegia and altered consciousness ranging from agitation to coma, seizures and myoclonus, especially affecting the face. The phytoplanktonic diatom Pseudo-nitzchia multiseries are the source of the toxic agent identified as domoic acid. This potent neurotoxin accumulates in mussels and clams that feed on toxic plankton during their bloom.

Diarrhetic shellfish poisoning

Diarrhetic shellfish poisoning [9] is the mildest and most benign of the toxic shellfish poisonings. Clinical features are limited to the GI tract and include diarrhea, nausea, vomiting, abdominal pain and cramps. Chills, fever or headache may be present in up to 10% of cases. These symptoms usually manifest in a period ranging from 30 mins to 6 hours after ingestion of contaminated shellfish. Patients often do not seek medical attention due to the transient nature of the illness and its spontaneous resolution. Diarrhetic shellfish poisoning is associated with the consumption of mussels, scallops, clams and oysters contaminated with biotoxins produced by toxic marine dinoflagellates during their blooms in summer.

Azaspiracids shellfish poisoning

Azaspiracids (AZA) [12] are polyether marine toxins that accumulate in various shellfish species and have been associated with severe gastrointestinal human intoxications. The first confirmed case was in 1995 in the Netherlands. This toxin has since been reported in Western Europe, Northwest Africa and Eastern Canada. There have been several attempts to identify the AZA producing organism(s) and the polyether structure of these compounds might suggest a dinoflagellate origin. Unlike many of the other well-described marine phycotoxins, relatively little is known about AZA. Similar to diarhetic shellfish toxins, human consumption of AZA-contaminated shellfish can result in severe acute symptoms that include nausea, vomiting, diarrhea, and stomach cramps that persist for 2-3 days. Toxicology studies have shown that AZA can induce widespread organ damage in mice and that they can be a potent toxin.

Adverse reactions to shellfish from bacterial and viral etiologies

In addition to the above specific five types of shellfish toxicity, the differential diagnosis should include bacterial toxins, viral and bacterial infections. Although rare, Vibrio vulnificus is the leading cause death related to seafood consumption in the United States. This bacterium is part of the natural flora of coastal environments worldwide and has been isolated in a variety of seafood including shrimp, fish, oysters and clams. Consumption of undercooked or raw seafood (primarily raw oysters) contaminated with V. vulnificus can result in severe fulminant sepsis and development of severe cellulitis with ecchymoses and bullae. Risk factors include immunocompromised conditions especially alcoholic liver disease, hepatitis B or hepatitis C, and male gender. Treatment includes antibiotics and supportive care.

Food-borne botulism occurs upon ingestion of food contaminated by preformed toxin that is produced by Clostridium botulinum. Initial manifestations are GI symptoms such as nausea, vomiting and diarrhea. Other initial symptoms include dry mouth, diplopia, blurred vision and photophobia caused by loss of pupillary light reflex. A symmetric descending flaccid paralysis may occur that can lead to respiratory failure.

Staphylococcal enterotoxin is produced by Staphylococcal aureus growing in the contaminated food. Onset of symptoms is usually rapid after ingestion. GI symptoms predominate with nausea, vomiting, abdominal cramps and diarrhea. This type of food poisoning usually occurs in foods that have been left at room temperature for some time.

Norwalk virus infection usually occurs after ingestion of contaminated raw shellfish and can spread through the fecal-oral route. Incubation period is 24-48 hours after exposure. Most common symptoms are nausea, vomiting and diarrhea which resolve after 24 hours.

Shellfish toxicity recognition and management

Shellfish poisoning may be under diagnosed particularly when mild, or misdiagnosed as allergy. The presence of similar symptoms in other individuals who shared the same meal, absence of prior reactions to the same shellfish and its subsequent tolerance without symptoms should favor toxicity. The level of suspicion should be higher in regions with seasonal algal blooms, high levels of biotoxins or toxic algae. In the majority of these toxic syndromes, the toxin does not alter the taste and appearance of the shellfish and is not inactivated by usual cooking.

Treatment for these toxic syndromes is mostly supportive with respiratory support in cases where neurological involvement can cause respiratory failure. In acute severe cases, gastric emptying and administration of activated charcoal has been recommended to help block further absorption of the toxins.

Shellfish allergens (Table ) [13]

Table 2

Allergenic proteins characterized in shellfish and other invertebrates

Hoffman et al [14] first isolated two allergens from raw and cooked shrimp, termed antigen I and antigen II respectively. The heat stable antigen II, demonstrated specific IgE binding in the sera of all 11 shrimp-allergic subjects tested. Subsequently, other studies confirmed that antigen II is the major shrimp allergen and was identified as tropomyosin [15-17]. The latter belongs to a family of proteins associated with the thin filament in muscle cells and microfilaments in non-muscle cells. Tropomyosin is not only a major crustacean allergen, it has also been demonstrated in a number of mollusk species [18]. In contrast to invertebrate tropomyosin, vertebrate tropomyosins are not allergenic. Dot blot and immunoblot analysis on subjects with a history of meat allergy to vertebrate meats did not show any IgE binding to tropomyosin of beef, pork, rabbit or chicken [19,20]. Similar studies demonstrated that shrimp allergic subjects’ specific IgE did not cross react with any mammalian tropomyosins or their fragments [18,21].

Tropomyosin is heat stable [16], yet its allergenicity may change by certain processing methods. Boiling may result in the Maillard reaction (glycation) and formation of neoepitopes [22], as demonstrated that in some patients, boiled shrimp extract induced larger skin test responses than raw extract [23]. Also, shrimp extract treated with high intensity ultrasound for 180 minutes demonstrated decreased binding with sera from shrimp allergic patients [24].

In addition to tropomyosin, other allergens have been identified and characterized in shellfish. Arginine kinase a potential new class of invertebrate pan-allergens have been identified in Pacific white shrimp and Black tiger prawn as Lit v 2 and Pen m 2 respectively [25,26]. Arginine kinase has also been found in mollusks [27], along with other allergens such as myosin heavy chain, haemocyanin, and amylase [28]. However, the clinical significance of these allergens in mollusks is currently undefined.

Two other allergens identified in the Pacific white shrimp (Litopenaeus vannamei) are myosin light chain kinase [29] and sarcoplasmic calcium binding protein [30], identified as Lit v 3 and Lit v 4 respectively. Sarcoplasmic calcium binding protein seems to be an important allergen in the pediatric population, recombinant sarcoplasmic calcium binding protein was recognized by serum IgE from 20 of 52 (38.4%) shrimp allergic subjects, with a higher frequency in children (17 out of 23; 74%) than in adults (3 out of 29; 10%) [30].

Cross-reactivity within the shellfish family

Subjects with shrimp hypersensitivity usually clinically react to other types of crustacea. Tropomyosin showed very high homologies of up to 98% among crustacean species, including crawfish, crab and lobster [17,31,32]. Crustacean allergic subjects also often react to species of the mollusk group. Leung et al [18] demonstrated in vitro that sera from nine crustacean allergic patients had IgE binding to antigens from all 10 mollusk species tested. However, in vitro cross-antigenicity does not necessarily indicate clinical cross allergenicity.

Furthermore, Jirapongsananuruk et al [33] demonstrated that shrimp allergy can be species-specific. Some studies reported clinical reactivity of 38% between shrimp and other crustacean members, 14% between crustacea and mollusks, and 49% between mollusk members [3,18,34,35]. It should be noted that these figures were derived primarily from self-reported clinical reactions.

Cross-reactivity with other invertebrate antigens

In patients with respiratory allergies, house dust mite (HDM) tropomyosin has been demonstrated to be a major allergen [36]. Tropomyosin from D. pteronyssinus (Der p 10) has homology of 75-80% to shrimp and fruitfly and 65% to mollusks [37]. Tropomyosins from HDM and cockroach have high sequence identities to shellfish tropomyosin of around 80% [38,39]. Such data indicate possible sensitization to tropomyosin by inhalation from a variety of non-crustacean sources [40], hence the emerging terminology “mite-crustaceans-mollusk syndrome”.

In a study of 9 Orthodox Jews, who observe Kosher dietary laws that prohibit eating shellfish, the presence of IgE sensitization to shrimp was explored [41]. All 9 subjects had perennial respiratory allergies and positive HDM skin test, which was also positive to shrimp in all 9 and to cockroach in 2 of 7 tested.

High levels of serum IgE to tropomyosin is correlated with severity of shellfish allergy, however it may not be the only allergen responsible for shellfish sensitization in HDM sensitized individuals [42]. Sera from patients with shrimp allergy and HDM sensitivity but not reactive to tropomyosin were studied and found to cross react with a new 20-kDa allergen present in both shrimp and HDM [43]. The authors postulated that this allergen could correspond to the sarcoplasmic calcium-binding protein and myosin light chain allergens. Arginine-Kinase found in decapod crustaceans and HDM (Der p 20) have also been proposed as a probable pan-allergen with 78% sequence homology with shrimp allergen Pen m 2 [44].

Some reports suggested that HDM injection immunotherapy may enhance sensitization or worsening allergy to shellfish [45-48]. However, a prospective study was conducted by Asero [49] on non shrimp-sensitized subjects receiving HDM injection immunotherapy for respiratory allergy and allowed to eat shellfish. After 3 years of HDM immunotherapy, participants showed no reactions to shrimp by skin testing or open oral challenge. Therefore, there is no strong evidence that shellfish allergy can develop through HDM immunotherapy.

It should be noted that crustacean and mollusk allergens do not cross-react with fish allergens and no reactivity between known allergens or homologous proteins have been demonstrated [50]. However, patients who are allergic to Anisakis simplex may react to parasitized fish or shellfish. Although tropomyosin might not be the major allergen in Anisakis allergy [51,52], possible clinical cross reactivity might occur in crustacean allergic subjects due to a high (74%) amino acid sequence homology of crustacean and Anisakis tropomyosin [50,53-55].

Clinical presentations of shellfish allergy

Symptoms of shellfish allergy can range from mild urticaria to life threatening anaphylaxis. Most reactions are IgE-mediated with rapid onset and may be gastrointestinal, cutaneous, or respiratory. Symptoms may be limited to transient oral itching or burning sensation (oral allergy syndrome) within minutes of eating shellfish [50]. Recently, a case of food protein-induced enterocolitis syndrome to shellfish has been reported in a 6-year-old boy after ingestion of clam [56]. Food-dependent exercise-induced anaphylaxis has also been described to shellfish [57,58]. In certain subjects, anaphylaxis may result by a synergistic effect of nonsteroidal anti-inflammatory drugs with shellfish intake [59].

Shellfish protein is a potent allergen and can provoke symptoms by inhalation or skin contact [60]. Airborne allergens are particularly abundant in the vicinity of cooking shellfish by boiling, steaming, or frying. Occupational exposure, such as in snow crab processing plants, not only can cause symptoms in highly allergic subjects, but can also cause de novo sensitization [61]. Symptoms may be limited to the respiratory tract or affect other systems such as the skin or systemic anaphylaxis. The reported estimate of prevalence of occupational asthma in shellfish-processing workers is 2-36% [62].

Exposure by skin contact occurs more in occupational settings and the manifestations are commonly cutaneous in the form of urticaria or allergic contact dermatitis, although occasionally it can be systemic. The prevalence of occupational contact dermatitis to shellfish ranged from 3 to 11% [62]. At least one case of contact urticaria to shrimp was reported to be caused by the protein in the shell and not to the meat itself [63].

Diagnostic approach

It is important at the outset to establish whether the adverse reaction is caused by shellfish allergy or toxicity. A detailed history is essential, with emphasis on the specific implicated type of seafood, the amount eaten, the type of symptoms, time of onset, and symptoms in other individuals who consumed the same meal. Management of food poisoning is mostly symptomatic.

In addition to the history and type of manifestation, allergic reactions are supported by documenting sensitization, i.e., positive skin test or elevated specific IgE level. Unless the patient had a life-threatening reaction, verification by a titrated oral challenge should be performed, preferably in a blind, placebo-controlled manner [64,65]. It is worth noting that skin testing with commercial extracts may give a false negative result whereas the prick-to-prick method can be more reliable, particularly by using the same implicated food. Carnes et al [23] demonstrated that using cooked instead of raw extracts for skin prick testing correlated well with food challenge.

If the medical history reveals concomitant factors, such as exercise, alcohol ingestion, or intake of nonsteroidal anti-inflammatory drugs, such factor(s) should be incorporated in the challenge test.

Management

In general, management of any food allergy is basically strict avoidance based on proven clinical reactions and not mere sensitization. Because of cross-reactivity, avoidance of all crustacea is generally advised. Avoidance of mollusks is not necessary unless the patient is concomitantly allergic to it. Since cross-reactivity among crustacea is not complete, it is possible that allergy be limited to certain crustacea members. Patients should be alerted to possible inadvertent hidden exposure to the offending food, particularly in restaurants where cooking equipment or serving utensils may be used for different foods.

In addition to strict avoidance, patients who have had severe reactions should be advised to wear a Medic Alert identification and be trained in using epinephrine autoinjector. Because future reactions may be more severe [66,67], some physicians tend to prescribe epinephrine autoinjectors to most food-allergic subjects.

Although there have been some recent investigational protocols for oral or sublingual immunotherapy to certain foods, to the best of our knowledge none has been done with shellfish. Perhaps some reports will be seen in the near future.

Allergic and toxic reactions to seafood

ASCIA PCC Allergic Reactions seafood 2020170.13 KB

Seafood allergy occurs most commonly where seafood is an important part of the diet, such as in Asia and Scandinavia. Some conditions caused by toxins or parasites in seafood can resemble allergic reactions to seafood.

Seafood allergy is not rare

Whilst figures vary from country to country, approximately 1% of the population is estimated to suffer from seafood allergy. It is more common in teenage and adult life than very early childhood. About 20% will grow out of their allergy with time.

Symptoms of seafood allergy

Many allergic reactions to seafood are mild and cause hives (urticaria), tingling of the throat and mouth, swelling (angioedema) and/or gut reactions (vomiting, diarrhoea).

The most dangerous symptoms are breathing difficulties or collapse, caused by a drop in blood pressure (shock), either of which can be life threatening. This is known as anaphylaxis, a severe allergic reaction.

Occasionally, breathing difficulties may occur from inhaling fumes when seafood is being cooked, and in seafood processing factories. Children with a history of asthma may be more likely to have severe allergic reactions to seafood.

Varieties of seafood

The major groups of seafood that can trigger allergic reactions are:

• Vertebrates (fish with a backbone)
  Fish including salmon, cod, mackerel, sardines, herring, anchovies, tuna, trout, haddock, John Dory, eels, rays.
• Invertebrates (without a backbone)                                                                                                        Shellfish: crustaceans including prawns/shrimps, lobster, crab, crayfish, yabbies; and molluscs including oysters, mussels, clams, octopus, squid, calamari, abalone, sea slugs.

Allergies may occur to one or many foods

Even though fish and shellfish live in the same place, the protein allergens present in one seafood group are generally considered to be very different to those in others. That means that one can be allergic to fish only, shellfish only or members of both groups. People who are allergic to one fish are usually (but not always) allergic to most other fish. Similarly, allergy to one crustacean usually means that all must be avoided. While those allergic to seafood from one group (e.g. crustaceans) can usually tolerate those from another (e.g. molluscs), this cannot be guaranteed without specific allergy testing. Similarly, people allergic to crustaceans may also be allergic to edible insects such as crickets (that may be used as cricket flour in baked goods).

Cross reactivity can be difficult to predict without testing

Cross reactivity means that a similar protein is present in a range of different foods. If the same protein is present in several foods, then that person may have allergic reactions to any food containing that protein. Examples of cross reactivity include people allergic to similar proteins present in one fish that are also present in other fish, or those allergic to proteins present in prawn, crab and lobster. Unfortunately, it is sometimes difficult to predict whether a person will be allergic to one unique protein allergen present in one food only, or several similar cross reactive proteins present in multiple foods, simply based on whether foods have a similar appearance. Therefore it is not possible to reliably predict the likelihood of allergy to one or more seafood group or individual seafood species without specific testing.

Cooking can sometimes affect tolerance

Seafood allergens are usually very heat stable and cannot easily be destroyed through cooking, although occasional individuals seem to tolerate tinned fish (intensely heat treated), yet are unable to tolerate the same fish freshly cooked. Do not try tinned fish unless advised by your allergy specialist.

Exposure may occur via multiple routes

While eating the food is the major trigger for allergic reactions, some sensitive individuals may react to the fumes when seafood is being cooked, and occasionally from touch, such as when cleaning and handling fish or even “injected”, such as penetration of the skin from fish hooks. Occupational asthma and contact rashes can also be a problem where exposure is frequent, such as in seafood processing factories, or in some food handlers such as chefs.

Delayed reactions to seafood

Allergic symptoms after contact with seafood are usually within minutes, however, delayed type reactions and particularly exercise-induced anaphylaxis is occasionally observed, particularly after ingestion of shellfish (such as oyster, abalone, squid and shrimp).

Avoiding seafood groups is an important part of management

Complete avoidance of one or more groups of seafood is often advised, yet this can be difficult. Accidental exposure is more likely to occur when eating away from home, particularly when eating at seafood restaurants.

Other potential sources of accidental exposure and cross-contamination include:

• Seafood platters and smorgasbords (best avoided).
• Asian foods, in which shellfish can be a common ingredient or contaminant (such as prawns in fried rice or soups, seafood extender).
• Food may be rolled in the same batter or cooked in the same oil as seafood (such as takeaway fish and chips).
• Commercial pizzas, where contamination may occur by virtue of the method of preparation.
• Seafood purchased from an outlet where both fish and shellfish are sold. Fish could be contaminated with shellfish and vice versa.
• Anchovies in Caesar salads and as an ingredient of Worcestershire sauce.
• Contaminated barbeques.
• Isinglass is sometimes used as a “fining” agent to remove cloudiness from beer and wine. Made from the swim bladder of certain types of fish, it consists almost entirely of collagen, and is considered very unlikely to cause allergic reactions. Use of isinglass in beer and wine has been exempted from mandatory labelling regulations in Australia.
• While the risk of allergic reactions to fish oils is considered to be very low in those allergic to fish due to the method of purification, those with fish allergy are advised to seek medical advice before consuming. Other sources of omega-3 fatty acids include evening primrose oil and flaxseed oil.
• People allergic to crustaceans may also be allergic to edible insects such as crickets (that may be used as cricket flour in baked goods).

Immunotherapy to “switch off” food allergy is not currently available, although this is an active area of research.

Seafood allergy and iodine allergy are unrelated

People allergic to seafood have allergic reactions to proteins present in the animal, not to iodine, which may be present as well. People who are allergic to seafood are not at an increased risk of allergic reactions to iodine (e.g. topical antiseptics such as Betadine or Povidine or intravenous x-ray radio-contrast agents). Conversely, people with iodine allergy are not at increased risk of seafood allergy.

Glucosamine is derived from shellfish

Glucosamine is a popular complementary medicine, used to treat osteoarthritis, which is derived from the outer coatings of shellfish such as crustaceans. Sometimes chondroitin sulphate is added, usually derived from shark cartilage. While people allergic to shellfish are sensitive to protein and not shell constituents, tests to exclude protein contamination are not routinely performed and there is little proof of safety in people with shellfish allergy, although challenge studies of small numbers of patients have demonstrated tolerance. Products registered in Australia and New Zealand carry labels warning against their use in people allergic to shellfish/crustaceans. This risk is considered to be very low. Nonetheless, “vegetarian” glucosamine is available which does not contain seafood allergen as it is produced in bacteria cultures.

Reliable diagnosis of food allergy is important

Your doctor will normally ask a series of questions that may help to narrow down the list of likely causes of allergy such as foods or medicines consumed that day, or exposure to stinging insects. This approach will also help to exclude conditions that can sometimes be confused with food allergy. Skin or blood allergen specific IgE allergy tests help confirm or exclude potential triggers. While the results of allergy testing are a guide to whether the person is allergic, results are not a reliable guide to whether the reaction will be mild or severe. It is also important to be aware that it may not be possible to test for all seafood species using commercial skin prick or blood allergy testing, since these are not available for all seafood species. For this reason, some allergy clinics will recommend that you bring samples of fresh food for testing.

Food allergy does not usually run in families

Most of the time, children with food allergy do not have parents with food allergy. However, if a family has one child with food allergy, their brothers and sisters are at a slightly higher risk of having food allergy themselves, although that risk is still relatively low. Some parents want to have their other children screened for food allergy. If the test is negative, that may be reassuring, but does not mean that the other child will never develop an allergy later. If their screening test is positive, it is not always clear whether it definitely represents allergy, or whether the sensitisation detected by the test is clinically irrelevant. The term “false positive” is sometimes used to describe this.

A positive allergy test is not the same as being food allergic

It is important to know that a positive skin or blood allergy test means that the body’s immune system has produced a response to a food, but sometimes these are false positives. In other words, the test may be positive yet the person can actually eat the food without a problem. For that reason, it is important to eventually confirm the significance of a positive allergy test (in some circumstances) with a deliberate supervised food challenge. In a child with a positive test of uncertain meaning, this is often done around school age under medical supervision. Interpretation of test results and a decision whether or not a food challenge should be undertaken will usually be made after discussion with a medical specialist (Allergist / Clinical Immunologist).

Unorthodox so-called allergy tests are unproven

There are several methods of unorthodox so-called ‘tests for food allergy’. Examples include cytotoxic food testing, Vega testing, kinesiology, iridology, pulse testing, Alcat testing, allergy elimination and Rinkel’s intradermal skin testing. These are unreliable, have no scientific basis and have no useful role in the assessment of allergy. So if you suspect a possible food allergy, have the suspicion confirmed with a reliable test

Some adverse reactions can resemble seafood allergic reactions

Some conditions caused by adverse reactions to seafood can resemble allergic reactions. These include:

Scombroid Fish Poisoning

This is an allergy like reaction that occurs after eating fish that have been improperly refrigerated after capture. Bacteria in and on the fish break down proteins into histamine, one of the major mediators of allergic reactions. Fish with a high content of red meat, which turns brown upon cooking are commonly involved such as mackerel, tuna, king fish, herring, sardines, marlin, anchovies and bluefish. Affected fish often have a metallic or peppery taste. Symptoms usually commence within 30 minutes of eating, and include flushing, itch, hives (urticaria), nausea, vomiting, stomach cramps, dizziness, palpitations and headache. Severe episodes may result in wheezing and dizziness or a drop in blood pressure. Mild symptoms may be treated with antihistamines. If severe symptoms are experience, then urgent medical assistance should be sought. Treatment usually involves taking antihistamines although in a hospital setting, adrenaline may also be given. Scombroid poisoning can be different by the pattern of symptoms and the absence of reactions with skin or blood allergy testing.

Anisakis Simplex

This is a nematode (worm) that is a fish parasite. It is found in most parts of the world and also in Australia [see reference below]. Cooking at temperatures above 60^oC or storage in industrial freezers for 2 days is required to kill the parasite. Fish that has been left for 48 hours or longer since being frozen should be discarded. Anasakis can cause two major problems in humans:

• Anisakis infection (anisakiasis) can result from eating raw, pickled or undercooked seafood such as sushi. Infection may cause nausea, vomiting, stomach pain, and sometimes appendicitis, bowel blockage or bleeding. Symptoms can occur due to inflammation in the gut at the site of entry of the parasite. Diagnosis requires an endoscopy where a specialist doctor uses a tube to observe the inside of the stomach and bowel without the need for major surgery and from which the parasite can be seen.The parasite usually gets destroyed by our immune system after 3 weeks.

• Anisakis allergy resembles other allergic reactions to food. In this case, the allergy is to the fish parasite, not to the fish itself. Reactions thus occur sometimes after eating seafood, rather than on every occasion. The allergens of Anisakis simplex appear to be not destroyed by heat or cooking and so allergic reactions may be triggered by dead parasites in fish that have been well cooked. Blood allergy testing is available to confirm suspected sensitivity to this parasite.

Ciguatera Poisoning, Paralytic Shellfish Poisoning and Diarrhoetic Shellfish Poisoning  

Ciguatera poisoning is caused by eating seafood that has been contaminated by algae-derived toxins. Ciguatera toxins are only present in fish, particularly large reef fish in the tropics. By contrast, paralytic shellfish poisoning and diarrhoetic shellfish poisoning is caused by shellfish contaminated with microorganisms (i.e. algae producing toxins), in particular mussels and oysters. These toxins or poisons interfere with the function of nerve endings. Symptoms occur within 2 to 3 hours of eating contaminated food, and consist of tingling of the lips, tongue and throat, often followed by stomach upset, headache, fever, muscle aches and pains and in the case of ciguatera poisoning, sometimes changes in blood pressure and heart rhythm. Numbness, collapse, coma and confusion have also been described. Most people recover within a few days or weeks with supportive treatment.

Metabisulfite Reactions 

Metabisulfite preservative can sometimes be used to stop crustaceans (such as prawns) from discolouring. Reactions to this preservative (also used in wine, beer and some dried fruit as a preservative) include wheezing/tight chest (more common in those with asthma), stomach irritation (e.g. nausea, pain) and very uncommonly, itch/rashes.

Table: Adverse reactions to seafood produced by various substances.

© ASCIA 2019

ASCIA is the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand.

ASCIA resources are based on published literature and expert review, however, they are not intended to replace medical advice. The content of ASCIA resources is not influenced by any commercial organisations.

For more information go to www.allergy.org.au

To donate to immunology/allergy research go to www.allergyimmunology.org.au

Updated April 2019

Symptoms, Food Allergy Testing, Epinephrine

Overview

What is a shellfish allergy?

A shellfish allergy is a type of food allergy. If you have a shellfish allergy, you experience unpleasant symptoms after eating shellfish.

Shellfish are animals that live in the water and have a shell-like exterior. There are two types of shellfish:

• Crustaceans: shrimp, crayfish, crab, lobster.
• Mollusks: clams, scallops, oysters, mussels.

Is a shellfish allergy the same as shellfish intolerance?

An allergist can figure out if you are allergic to shellfish or have an intolerance. The difference matters. While an intolerance causes uncomfortable symptoms, an allergy can potentially be life-threatening.

Who gets shellfish allergies?

Anyone can develop a shellfish allergy — even if you’ve had shellfish before without any problems. Although it can occur at any age, it appears more often in adults than in children. About 60% of people who have a shellfish allergy first get symptoms as an adult. The reason may be that children typically don’t eat shellfish. People often eat shellfish for the first time as adults, which may be why symptoms appear later in life.

Is a shellfish allergy the same as a fish allergy?

No, shellfish allergies and fish allergies are different. You may have a shellfish allergy but be able to eat fish (and vice versa).

How common is a shellfish allergy?

A study found that approximately 2% of the population (around 6 million people) has a seafood allergy (meaning they are allergic to fish, shellfish or both).

Do all shellfish cause the same reaction?

Often, if you have an allergy to one type of shellfish, you will have an allergy to other types. Crustaceans cause more allergic reactions than mollusks.

You might have a reaction after eating lobster, for example, but eat scallops without a problem. If you have symptoms after eating shellfish, talk with your healthcare provider or allergist before eating any type of shellfish.

Is an allergy to shellfish related to an iodine allergy?

Shellfish allergies are sometimes confused with iodine allergies. That’s because shellfish often contains iodine. But having a shellfish allergy doesn’t necessarily mean you’re allergic to iodine. If you have a shellfish allergy, you don’t have to worry about reactions with radiocontrast material. (Certain diagnostic imaging scans use radiocontrast material, which contains iodine.)

What shellfish should I avoid if I have an allergy?

If you have a shellfish allergy, don’t eat these ingredients and foods:

• Abalone.
• Clams (such as cherrystone, littleneck, pismo, quahog).
• Cockle.
• Conch.
• Crab.
• Crawfish and crayfish.
• Lobster.
• Mollusks.
• Mussels.
• Octopus.
• Oysters.
• Scallops.
• Shrimp and prawns.
• Snails.
• Squid (calamari).

Symptoms and Causes

What causes a shellfish allergy?

A shellfish allergy, or any food allergy, results from an immune system overreaction. Your immune system defends your body from invaders, such as infections. A food allergy occurs when your body identifies a food substance as a foreign invader and attacks it.

When do symptoms appear?

Typically, allergic reactions to food occur soon after eating the food — within a few minutes to a few hours.

What are symptoms of a shellfish allergy?

Shellfish allergy symptoms range from mild to severe. One person may experience itching and hives while another could have a life-threatening reaction, such as breathing problems. Symptoms can affect many different parts of the body: skin, respiration, digestion and heart.

Shellfish allergy symptoms include:

• Itching.
• Hives.
• Eczema.
• Tingling or swelling of the lips, tongue or throat.
• Chest tightness, wheezing, coughing, shortness of breath and difficulty breathing.
• Stomach issues: pain, nausea, indigestion, vomiting or diarrhea.
• Dizziness, weak pulse or fainting.
• Pale or blue skin coloring.
• Anaphylaxis, a severe, potentially fatal allergic reaction, often involving several parts of the body.

Diagnosis and Tests

How is a shellfish allergy diagnosed?

Shellfish allergies can be challenging to diagnose. Symptoms differ from person to person, and the same person can have different reactions after eating shellfish. You may have a reaction without even eating shellfish — for example, if you’re cooking it or shellfish contaminates your food.

To diagnose a shellfish allergy, your healthcare provider (or allergist, a specialist in allergies) will ask you about your symptoms. You may need to answer:

• What did you eat? And how much?
• When did symptoms develop?
• What symptoms did you have?
• How long did symptoms last?

Will I need food allergy testing to diagnose a shellfish allergy?

After asking you about your symptom history, your provider may do food allergy testing to confirm a diagnosis:

• Skin prick test: During this in-office test, your provider places a drop of the allergen on your skin and pricks your skin. The drop seeps into your skin. Your provider will confirm a diagnosis if a red, itchy bump appears after 15 to 30 minutes.
• Blood test: A blood test can help detect whether you have a specific food allergy.

These tests are not conclusive. Together with your symptoms and history, your provider will make a diagnosis.

Will I need an oral food challenge?

This test can provide a definitive diagnosis. Under strict, careful supervision, you eat a small amount of the allergen. Your provider increases the dose gradually and notes your symptoms. Occasionally, allergists can use this test to see if you’ve outgrown the allergy. However, most people do not outgrow shellfish allergies.

Management and Treatment

How do I manage a shellfish allergy?

You can’t become “un-allergic” to shellfish. The best way to keep yourself healthy is to avoid shellfish. Besides avoiding shellfish itself, make sure you avoid foods that contain shellfish.

The Food and Drug Administration (FDA) requires food manufacturers to list common food allergens, such as shellfish, on food labels. The food label lists the allergen either in the ingredients list or after the list. For example, if a product contains abalone, a species of shellfish, the label will state “abalone (shellfish)” in the ingredients or “contains shellfish” after the ingredients list.

What treatments are used if I have an allergic reaction?

Epinephrine is the main treatment for anaphylaxis. Once your provider has confirmed a shellfish allergy, you will most likely get a prescription for self-injectable epinephrine (EpiPen®). Your provider will teach you how to use it.

If you have a severe allergic reaction and inject yourself with epinephrine, the next step is to call 911. Make sure to tell the dispatcher what happened and that you used your epinephrine injection. Emergency medical technicians (EMTs) may need to give you another dose when they arrive.

When should I use an epinephrine injection?

Use the injection right away if you notice:

• Shortness of breath, coughing, weak pulse, hives, throat tightness or trouble breathing.
• A combination of symptoms from different areas of the body, such as hives and swelling along with vomiting and diarrhea.

If I’m not sure my reaction is considered “severe,” should I inject myself with epinephrine?

In general, allergists recommend using the injection. The benefits of using it outweigh the risks of a potentially unnecessary dose.

What other medicines can treat a shellfish allergy?

If you have mild symptoms, your healthcare provider may recommend an antihistamine or corticosteroid. However, only epinephrine can treat the severe symptoms of anaphylaxis.

Prevention

How can I avoid an allergic reaction to shellfish?

The only way to avoid the negative effects of shellfish is to avoid shellfish entirely.

How else can I lower my risk for an allergic reaction?

In addition to not eating shellfish, these precautions can help you stay safe:

• Try not to cook or touch shellfish: Particles can become airborne during cooking and cause an allergic reaction. Some people have a reaction from handling shellfish.
• Use caution in seafood restaurants: Even non-shellfish dishes prepared in seafood restaurants may contain shellfish. Restaurants often use the same cooking equipment (and often, the same frying oil) for shellfish and non-shellfish dishes, so there may be contamination.

What other foods might contain shellfish?

These food items may contain shellfish as well, so avoid eating them:

• Bouillabaisse, cioppino and other seafood stews.
• Cuttlefish ink.
• Fish stock.
• Imitation fish.
• Seafood flavoring.
• Surimi.

Outlook / Prognosis

Is a shellfish allergy dangerous?

Any food allergy can be dangerous. Even if you’ve only experienced mild allergic symptoms to a food, you can always potentially have a dangerous reaction to that same food. It’s smart to be careful and prepared. Carry your epinephrine injection with you at all times. Note the expiration date so you can get a new one before it expires.

Does a shellfish allergy go away?

Most people who have a shellfish allergy have it for life. It does not go away over time.

Living With

If I have a shellfish allergy, how do I take care of myself?

You can live a healthy, enjoyable, active life with a shellfish allergy. Take some precautions to keep yourself healthy and feeling your best:

• Know what you’re eating and drinking.
• Check label ingredients — even if it’s a product you’ve eaten safely before. Often, manufacturers change recipes, and shellfish may have been added.
• If your child is allergic, teach them not to accept food from friends.
• Be restaurant safe: Ask detailed questions about ingredients and food preparation when you eat out.
• Wear your medical alert bracelet or carry an alert card with you.
• If your healthcare provider prescribed self-injectable epinephrine, carry it with you at all times. Make sure you have two doses available, as you may need to repeat the injection.

A note from Cleveland Clinic

A shellfish allergy can be annoying. It can interfere with your life, especially if you enjoy eating seafood. It’s smart to take precautions and avoid shellfish, even if you only experience mild symptoms. By avoiding shellfish, you can almost eliminate the uncomfortable (and potentially life-threatening) risks of an allergic reaction. If you notice symptoms after eating shellfish, talk to your healthcare provider or allergist to get a diagnosis. Your provider will talk to you about how to best care for yourself and explain how to use an epinephrine auto-injector.

Cross-reactivity between prawn and shrimp, and possible delayed allergic reactions to shrimp

Question:

Reviewed 4/17/2019

12/9/2013

I have an adult patient who claims she can tolerate shrimp, crab and lobster, but not prawns which are essentially large shrimp. It makes no difference in the method or length of cooking time. This makes no sense to me, since the allergen tropomyosin is common to all crustaceans and even the mollusks.

A separate but related observation is that several patients have delayed reactions to shrimp, i.e. eating it for dinner, going to bed without symptoms and awaking the next morning with facial hives and/or lip swelling. I’ve heard this story about a dozen times, and frequently the patients tolerate shrimp at other times (including after the so-called delayed reaction). Inquiries into possible “red herring” concurrent ingestion, such as NSAIDs, etc. is always negative. Any explanation for either observation?

Answer:

Thank you for your inquiry.

The first question is easier to answer than the second. You are correct that tropomyosin is the major allergen in shrimp and in prawn as well. However, the situation is not as simple as that. As you can see from the abstracts copied below, there are other allergens in prawn that may not be present in all shrimp. And, even though tropomyosin is relatively well preserved, there are clearly different species of tropomyosin. Thus, it is not uncommon to see patients who may react to one species of crustacean and not another even though tropomyosin is a common allergen in many. If you would like to read further about this, the full article by Woo and Bhana is available to you free of charge online. You can access it by copying and pasting the link below in your web browser.

Unfortunately I have no ready explanation for your second question. Although the lay literature does contain references to delayed reactions to shrimp (as well as other foods), I could find nothing on a search of the scientific literature citing a reference to this. For your interest, however, here is a link to a lay website that discusses patients’ observations of delayed reactions to shrimp, listing it as “one of the top 20 foods to which delayed reactions occur.” But, as noted, I have no explanation for this phenomenon and could find no reference to it in the scientific literature. Therefore any explanation I could offer you would only be conjecture.

Thank you again for your inquiry and we hope this response is helpful to you.

Not all shellfish “allergy” is allergy!

Chee K Woo and Sami L Bahna*
Clinical and Translational Allergy 2011, 1:3

Abstract

The popularity of shellfish has been increasing worldwide, with a consequent increase in adverse reactions that can be allergic or toxic. The approximate prevalence of shellfish allergy is estimated at 0.5-2.5% of the general population, depending on degree of consumption by age and geographic regions. The manifestations of shellfish allergy vary widely, but it tends to be more severe than most other food allergens.

Tropomyosin is the major allergen and is responsible for cross-reactivity between members of the shellfish family, particularly among the crustacea. Newly described allergens and subtle differences in the structures of tropomyosin between different species of shellfish could account for the discrepancy between in vitro cross-antigenicity and clinical cross-allergenicity. The diagnosis requires a thorough medical history supported by skin testing or measurement of specific IgE level, and confirmed by appropriate oral challenge testing unless the reaction was life-threatening.

Management of shellfish allergy is basically strict elimination, which in highly allergic subjects may include avoidance of touching or smelling and the availability of self-administered epinephrine. Specific immunotherapy is not currently available and requires the development of safe and effective protocols.

Malays J Med Sci. 2011 Jul-Sep; 18(3): 27–32.

PMCID: PMC3216233

Identification of Major and Minor Allergens of Black Tiger Prawn (Penaeus monodon) and King Prawn (Penaeus latisulcatus)

Abstract
Background: Prawns and shrimp are a frequent cause of seafood allergy mediated by IgE antibodies. Penaeus monodon and Penaeus latisulcatus, commonly known as black tiger prawn and king prawn, respectively, are among the most frequently consumed prawns in Malaysia. The aim of this study was to identify the IgE-binding proteins of these 2 prawn species.
Methods: Raw and boiled prawn extracts were prepared and then resolved by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). IgE-immunoblotting was then performed using sera from patients with positive skin prick tests to the raw prawn extracts.
Results: SDS-PAGE analysis of the raw extracts of both prawn species revealed 23 protein bands; the boiled extracts yielded fewer protein bands. The bands in the range of 40 to 100 kDa were sensitive to heat and therefore were not found in the boiled extracts. Immunoblot of raw extracts of black tiger prawns and king prawns yielded 14 and 11 IgE-binding proteins, respectively, with molecular weights of between 15 and 200 kDa. Proteins at 36, 42, and 49 kDa were detected as the major allergens in both species of prawns. A protein of 75 kDa was also identified as a major allergen in black tiger prawns. Other potential allergens were also observed at various molecular masses.
Conclusion: Proteins of 36, 42, and 49 kDa were identified as the major allergens of both species of prawns. The 36 and 42 kDa proteins are hypothesised to be tropomyosin and arginine kinase, respectively. A high molecular weight protein of 75 kDa was found to be an additional major allergen in black tiger prawns.
Keywords: allergens, allergy and clinical immunology, hypersensitivity, Penaeus, immunoblotting, tropomyosin

Int Arch Allergy Immunol. 2008;146(2):91-8. doi: 10.1159/000113512. Epub 2008 Jan 18.

Sarcoplasmic calcium-binding protein: identification as a new allergen of the black tiger shrimp Penaeus monodon.

Shiomi K, Sato Y, Hamamoto S, Mita H, Shimakura K.

Source

Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan.

Abstract
Background: Tropomyosin and arginine kinase have been identified as crustacean allergens. During purification of arginine kinase from black tiger shrimp Penaeus monodon, we found a new allergen of 20-kDa.
Methods: A 20-kDa allergen was purified from the abdominal muscle of black tiger shrimp by salting-out, anion-exchange HPLC and reverse-phase HPLC. Following digestion of the 20-kDa allergen with lysyl endopeptidase, peptide fragments were isolated by reverse-phase HPLC, and 2 of them were sequenced. The 20-kDa allergen, together with tropomyosin and arginine kinase purified from black tiger shrimp, was evaluated for IgE reactivity by ELISA. Five species of crustaceans (kuruma shrimp, American lobster, pink shrimp, king crab and snow crab) were surveyed for the 20-kDa allergen by immunoblotting.
Results: The 20-kDa allergen was purified from black tiger shrimp and identified as a sarcoplasmic calcium-binding protein (SCP) based on the determined amino acid sequences of 2 enzymatic fragments. Of 16 sera from crustacean-allergic patients, 8 and 13 reacted to SCP and tropomyosin, respectively; the reactivity to arginine kinase was weakly recognized with 10 sera. In immunoblotting, an IgE-reactive 20-kDa protein was also detected in kuruma shrimp, American lobster and pink shrimp but not in 2 species of crab. Preadsorption of the sera with black tiger shrimp SCP abolished the IgE reactivity of the 20-kDa protein, suggesting the 20-kDa protein to be an SCP.
Conclusions: SCP is a new crustacean allergen, and distribution of IgE-reactive SCP is probably limited to shrimp and crayfish.

Sincerely,

Phil Lieberman, M.D.

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The classification of garden asters is an attempt by scientists to put things in order in an incredible variety of varieties and types of asters: today there are about 40 groups of annual or garden asters (Callistephus chinensis) in culture, including about 4000 varieties that differ in the size of the bush, color and shape of the inflorescence and flowering time.Continue reading Classification of garden asters →

Did you know that the garden aster (aka one-year-old aster, aka Chinese aster), one of the autumn flowers beloved by all summer residents, is not actually an aster, but its close relative, a native of northern China, Callistephus Chinese (Latin Callistephus – “Beautiful wreath”)? In the wild, callistephus is ubiquitous in North China, Mongolia, Korea, and the Russian Far East.Continue reading Garden aster →

clay pot – Russian translation – Linguee

Skin Rash from eating shrimp 2021

If you develop a skin rash after eating shrimp, you are most likely allergic to food.Shellfish allergies are one of the most common food allergies. Shrimp is a type of shellfish, a marine animal with a shell. Shellfish include both shellfish and crustaceans such as shellfish, oysters, ears, squid, shrimp, crabs, and lobsters. The development of a skin rash is one of the first signs of an allergic reaction and should not be ignored. If you suspect you may be allergic to shrimp or other foods, see your doctor. Tests are available to confirm this allergy.

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How it happens

Any allergy to any food begins with an abnormal immune response. Certain proteins in shrimp are mistakenly recognized by your body’s immune system as harmful. This triggers a response from the immune system to release antibodies to fight a protein called tropomyosin, according to the University of Nebraska-Lincoln. The next time you are exposed to shrimp protein, your immune system releases histamine, a substance responsible for the development of skin rashes and other symptoms.

Symptoms

An allergic reaction can cause a skin rash within minutes to several hours after eating shrimp. Your reaction to shrimp can vary; Milder symptoms include the development of rash and itching. If you have a stronger reaction, you may develop other symptoms, including hives and swelling of your face, lips, mouth, and tongue. If you are very allergic, you may also start wheezing and feel like your throat is closing, making it difficult to breathe or swallow.This is a serious situation that requires immediate medical attention. If you develop a skin rash after eating shrimp, do not eat it again until the allergy is confirmed. Allergic reactions may gradually worsen after each exposure.

Severe reaction

Shrimp and other food allergies are the leading cause of anaphylaxis, a severe allergic reaction. MedlinePlus states that anaphylaxis is a life-threatening reaction of the entire body to an allergen, causing widespread release of histamine from all body tissues.Symptoms develop very quickly and include abdominal cramps, confusion, slurred speech, severe wheezing, shortness of breath, vomiting, diarrhea, fast heartbeat, and fainting. If treated immediately, anaphylaxis can lead to coma and death. This is a medical emergency requiring 911 support.

Safety precautions

Once you develop a skin rash after eating shrimp, you are likely to be allergic for life. It is imperative that you avoid contact with shrimp or shrimp products.Read all food labels that should indicate if they contain shellfish. You should ask detailed questions when you eat, especially in seafood restaurants; you need to know what foods are cooked in the vicinity of the shrimp. You should also wear a medical bracelet that warns you that you are allergic to shrimp. Antihistamines will soothe skin rashes and hives, but you will need an epinephrine injection to reverse a severe reaction. Talk to your doctor; if your allergies are severe, you may need to wear injectable epinephrine.

90,000 What are the signs of an allergic reaction to shrimp?

Allergic reaction to shrimp is common because many people are allergic to shellfish. Some people have mild reactions such as hives, tingling in the mouth, and mild swelling of parts of the body. Other people have severe allergic reactions to even tiny pieces of shrimp, which can include difficulty breathing; nausea and vomiting; and severe swelling of the face, throat, or lips.Sometimes an allergic reaction to shrimp is mistaken for food poisoning and vice versa. Part of recognizing an allergic reaction to shrimp is knowing if the person has reactions to other shellfish such as crab and squid.

Hives are a very common allergic reaction and appear as red scars that itch or sting. Tingling in the mouth is a harmless reaction to an allergen but may be accompanied by swelling. Minor swelling of the face, lips, and throat is sometimes difficult to detect, although it is also harmless as long as breathing is not disturbed.These allergic reactions to shrimp are relatively minor and usually do not require medical attention.

Another sign of an allergic reaction to shrimp is shortness of breath, which is usually characterized by a wheezing noise when inhaling and an inability to speak in a hoarse whisper. Difficulty breathing is caused by severe swelling in the throat or mouth, which narrows a person’s airways. This is a serious reaction that requires immediate medical attention. Until help arrives, the person should lie down without a pillow to open their airways as much as possible.

Nausea and vomiting are other signs of an allergic reaction to shrimp. These signs may be accompanied by abdominal pain or diarrhea. If these reactions are severe, medical attention may be needed. A doctor may recommend over-the-counter nausea medications to ease the discomfort until the problem goes away on its own.

People sometimes confuse shellfish allergy with food poisoning because they have never had a bad experience with shrimp or crab before.Most people develop food allergies in early childhood and they either disappear with age or stay with them forever. However, it is possible for older children or adults to develop shellfish allergy. In theory, a person could eat shrimp from time to time or regularly and then be allergic to it one day.

Most people who are allergic to shrimp are also allergic to other shellfish, but this happens both ways. A person who is allergic to crab is likely to have an allergic reaction to shrimp.Knowing a person’s allergies can help prevent and recognize allergic reactions.

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Cocktail Salad | Medovkrym.ru

Guests are on the doorstep and you urgently need to serve something to the table ?! No problem! Today we have prepared for you, as always, a simple but very tasty recipe – a cocktail salad with avocado and shrimps. Just 15 minutes and the appetizer is ready!

To prepare such a snack in your refrigerator (in the case of screams, in the freezer) there should be:

• frozen shrimp (portioned – only one shrimp per cocktail salad)
• avocado (not very hard, but not very soft either – something in between).If you bought a hard avocado and you don’t have time to wait until it ripens, use our recommendation. Place the avocado (whole) in one banana container for a couple of days. Banana gives off a specific gas that ripens fruits / vegetables,
  that are next to it.
• cheese (any hard cheese)
• lemon (more precisely lemon juice)
• dill (can be in the form of winter harvesting – frozen)
• honey (any variety you like from our rich assortment, presented in the section “Honey”.
  Everything!

Cocktail Salad – Preparation:

The shrimps should be thawed (if you need to speed up the process, fill them with cold water for five minutes) and cook until tender in salted water with dill.
Allow the shrimp to cool and peel.
Peel the avocado and cut it into small cubes, also do with the cheese.
Prepare a dressing for our salad.
To do this, squeeze out the lemon juice and combine it with honey.
We will serve the salad in portions – in glasses, yes, this does not require special dishes at all!
Put the diced avocado on the bottom of the glass, delicately place the cheese and shrimp on top of the side.
Add dressing to each glass.
Decorate the cocktail salad with a sprig of fresh dill.

Attention!
For nut lovers!

In the third layer (on top, on the cheese), you can add chopped nuts – this will also be very tasty.
Fresh nuts (hazelnut, walnuts, dessert almonds, Nikitsky almonds, hazelnuts, red-leaved hazelnuts), saturated with the Crimean sun, can be found in the Nuts section.
We offer you to purchase nuts, both in shell and without it (peeled).

90,000 Gastronomic travel with Irina Klimenko: How shrimp is caught in Norway and how they are eaten

With this article, we continue a series of publications devoted to the culinary and gastronomic traditions of different countries and peoples. Here you will not find any specific recipes, but you will learn a lot of new and even unexpected from the world of food and drinks

Irina Klimenko. Gastronomic journalist, food critic, translator.Aries. Likes to interview chefs, cheese makers and winemakers in their workplaces. He never imposes his gastronomic opinion.

Even those of us who have not yet been to Norway are well aware that this country is famous for its long seaside and excellent fish cuisine. The northern regions of Norway, which is beyond the Arctic Circle, attract tourists not only with the northern lights in winter and the never-setting bright sun in summer, but also with very interesting gastronomic discoveries.

It turns out that the beautiful Latin word borealis (northern) is present not only in the name of such a grandiose natural phenomenon as the northern lights – Aurora borealis.The Norwegian deep-sea shrimp, 10-12 cm in size and weighing only about 40 grams, is called Pandalus borealis and is found in these cold seas. She lives a fairly long life of 4-5 years before she is caught, and manages to accumulate much more nutrients and vitamins than her relatives living in the warm seas of Southeast Asia.

And she is also known for the fact that somewhere in the middle of her life she decisively changes her gender from male to female. You rarely see this! After the autumn mating as a female, such a shrimp bears eggs all winter.It is for this reason that the largest and most delicious shrimp – excuse me, females. Shrimp fishing is conducted all year round, so if you are lucky, you can watch how trawls catch this tasty catch.

Shrimp caught in Norwegian waters are usually in place and processed: boiled, peeled and frozen. Of course, northern shrimp is best consumed fresh – boiled, but not yet frozen. The Norwegians did not philosophize slyly and came up with a very simple way to use their boiled shrimp – with fresh bread and mayonnaise.A kind of sandwich turns out, it is even served in restaurants. And they usually make it of huge sizes, for a whole plate. Easy to prepare and shrimp cocktail. Shrimps are actively used in salads and omelets.

Sorting shrimp right on board when they are not just fresh, but still alive

And according to tradition about accompanying drinks. For obvious natural and climatic reasons, Norway does not produce its own wine, otherwise a cool white dry from Chardonnay or Sauvignon Blanc grapes would be quite suitable for a shrimp menu.But beer is respected there as well as ours. You can also start your meal – or end it – with a portion of the typical strong alcohol for this northern country under the philosophical name aquavit (aquavit, water of life).

90,000 Bee family – 41

12 V, 20 W (halogen in electrical stores).
It is best to use ammeters rated to measure amperage up to 2 A in an alternating current circuit as a continuity indicator.They do not dissipate energy in the form of heat on themselves; this energy can be used to heat an additional hive. But nx is not visible from afar, whether the chain is working or not.
To find a fault in a circuit, you need an ohm meter or mu. a meter capable of measuring resistance in a circuit. Measurements should be carried out with the circuit disconnected from the mains!
If you take a spiral from a 600 W electric stove as heating elements, then to get a separate heater for a hive with a power of 18 W you will have to cut it into 33 pieces.You yourself understand that the pieces will turn out to be small. Therefore, it is advisable to find a chrome wire, using an ammeter and a voltmeter (plp multimeter, but alternately including it in the circuit) to find the length to obtain the desired power. Usually it turns out: a wire of the day with a 0.8 mm meter, for 18 W of power – 3 m long; for wire of the day with a meter of 0.5 mm – length 1m; then wind these pieces on a nail to get a spiral and stretch them a little so that the spirals do not touch each other.
If you want to use heaters to heat, say, not 13 hives, but 17, connecting Iix also in series and in no other way (!), Then the power of the heaters will be only 10 W each, but they will raise the temperature by 10-12 °.In early spring, this is not enough. The table below will help you determine the number of heaters if the power of 18 W for one hive seems large. The data has been compiled without taking into account the heat dissipation of the control devices. We will assume that the control lamp takes energy equal to that released on the 1st heater, and the ammeter does not take it at all.
Scheme for switching on heating elements using a thermostat
Without a thermostat, it is possible to connect low-power heating elements when there is no danger of overheating the nest of the hive, but in this case, I recommend that you turn on the heating elements through a thermostat.The relay automatically disconnects the circuit when heating to the set temperature,
and after cooling to the temperature determined by the hysteresis (lagging behind the set), reconnects the heating elements to the current source. Of course, the smaller the hysteresis, the better, but the more expensive the thermostat is.
heating element
The sensor from the thermostat is installed in the hive, but without bees, with 1 heater, so that it reacts to heat losses depending on the design of the hive itself. The empty hive, on which I drew your attention, is completed in the same way as all apiary hives – 2 buildings with frames, honey in the 2nd building, empty frames in the 1st building, also open entrances, but barred nets from penetration thief.
Without the influence of bees, the heating element in the hive with and without bees with the help of a thermostat maintains the temperature set by the Vamp.

Botan shrimp price we offer to buy large crested botan shrimp.

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