Allergy to conch?

[DrRalph]

I've been working with one of our members who asked if a person who is allergic to crustaceans (lobster, shrimp) would also be allergic to conch (shellfish)? I found an article in the Food Allergy Initiative (http://www.foodallergyinitiative.org/section_home.cfm?section_id=3&sub_section_id=4)which claims that these people are, in fact allergic to mollusks, which include conch (Strombidae):

"Unlike fish, if a person is allergic to shellfish, they usually must avoid all types of shellfish, as most types will cause an allergic reaction. This includes all species of crab, lobster, shrimp, prawn, and all types of mollusks (clams, mussels and scallops)."

A statement on the Food and Nutrition section of the Health Canada web site (http://www.hc-sc.gc.ca/fn-an/securit/allerg/fs-if/allergen_fish-poisson_e.html)said this:

"It is possible for some people who are allergic to one type of seafood (fish, shellfish or crustacean) to eat other types of seafood without having a reaction. However, studies show that when a person has a specific seafood allergy he/she may also be allergic to other species within the same group. For example, if you're allergic to cod, you may also be allergic to pike as both are fish; if you're allergic to shrimp, you may also be allergic to lobster as both are crustaceans; if you're allergic to mussels, you may also be allergic to clams as both are shellfish. If someone is allergic to one type of seafood - crustaceans or fish or shellfish - he/she will not necessarily be allergic to the other types. Consult your allergist before experimenting."

Then I made a couple of phone calls, and I found two people who have profound allergies to crustaceans, but have no problem eating conch. And, the situation is rendered even more confusing because people often refer to lobster and shrimp as "shellfish," and they're really not; conch, mussels, and scallops are true shellfish.

Can anyone out there comment on their personal experience?

[BA]

Hey Dr Ralph,
Fortunately not my own body's experience, but my father-in-laws...
He has a VIOLENT (nasty) reaction to conch, but LOVES shrimp, oysters, lobster, crabs, scallops and anything else I can think of. The latest sneaky culprit was the conch & rice at Wally's. He thought it was just peas & rice (didn't notice description in menu) and the amount of conch was very slight (compared to a traditional conch dish). The reaction was a bit delayed - I guess from the amount consumed. But once it hit, it hit hard. He spent the afternoon and rest of the night in the head. The sad thing is - he loves the stuff, and has been kind of stubborn in accepting the fact that he just can't eat it. It gets him every time!
Being the troopers we were, we continued to have fun while he was in misery. We were giving him privacy... yeah, that's the reason we're sticking to!

[SamFamAustin]

I didn't want to be gross, but there WAS a reason why I wrote "Is conch edible." I just might be one of those afflicted like BA's dad in-law. ;)

Funny you BA should bring up the dad-in-law thing, because mine is allergic as the devil to all kinds of crab, but can eat all other kinds of seafood just fine. Weird?

[PELLUCID]

When I lived in Seattle I was friends with "The Bug Man" who made his living with a traveling bug show. The school board paid him to go around to the schools and teach kids about insects, for science class. A couple times a year, he and his bug-collecting buddies would have a potluck "Bugs & Beer" party where they would show off their bugs. The black light show with flourescent scorpions was always a big hit.

Anyhoo... a question he often got was "Are bugs edible?" "Sure they are..." he'd reply "but I can't eat them, because I'm allergic to shrimp!"

Apparently, something in the exoskeletons of both shrimp and insects triggered the allergy.

Do we have any evolutionary biologists (or just plain old Linnaeans?) on the board? I'm pretty sure that insects and crustaceans are a lot closer genetically than crustaceans and mollusks. As vertebrates, fish are even more remotely related. We call 'em all seafood, because we see 'em in the sea and eat 'em. But it seems to me that if you are allergic to all of them, you may be allergic to a lot of things on dry land as well.

[Moderator6]

I've been working with one of our members who asked if a person who is allergic to crustaceans (lobster, shrimp) would also be allergic to conch (shellfish)? I found an article in the Food Allergy Initiative (http://www.foodallergyinitiative.org/section_home.cfm?section_id=3&sub_section_id=4)which claims that these people are, in fact allergic to mollusks, which include conch (Strombidae):

"Unlike fish, if a person is allergic to shellfish, they usually must avoid all types of shellfish, as most types will cause an allergic reaction. This includes all species of crab, lobster, shrimp, prawn, and all types of mollusks (clams, mussels and scallops)."

A statement on the Food and Nutrition section of the Health Canada web site (http://www.hc-sc.gc.ca/fn-an/securit/allerg/fs-if/allergen_fish-poisson_e.html)said this:

"It is possible for some people who are allergic to one type of seafood (fish, shellfish or crustacean) to eat other types of seafood without having a reaction. However, studies show that when a person has a specific seafood allergy he/she may also be allergic to other species within the same group. For example, if you're allergic to cod, you may also be allergic to pike as both are fish; if you're allergic to shrimp, you may also be allergic to lobster as both are crustaceans; if you're allergic to mussels, you may also be allergic to clams as both are shellfish. If someone is allergic to one type of seafood - crustaceans or fish or shellfish - he/she will not necessarily be allergic to the other types. Consult your allergist before experimenting."

Then I made a couple of phone calls, and I found two people who have profound allergies to crustaceans, but have no problem eating conch. And, the situation is rendered even more confusing because people often refer to lobster and shrimp as "shellfish," and they're really not; conch, mussels, and scallops are true shellfish.

Can anyone out there comment on their personal experience?


Here is one for ya Doc. I love crawfish but every once in a while, I will get an allergic reaction after I eat it. I get itchy all over, head to toe but no rash. Someone suggested it might be where the crawfish are caught. It could be a high quantity of iodine. I never know when it might happen so when I know I am going to eat crawfish, I keep benedryl handy. It happened one time when I ate Wahoo. Strange!!!

[ericinsc]

I have a "mollusk" allergy, I guess. I have had severe reactions to scallops, mussels, and on my first trip to Elbow Cay last June , spent 3 days in bed very sick after eating conch for 3 days. I have no trouble with shrimp or lobster, and can eat the others if they are WELL DONE (I do not like raw oysters, so I have had no trouble there).

On my last physical soon after the June trip, I told my GP, and he told me it was probably a bacteria commomly found in the bivalve , or bottom-filterers, group, and not Iodine related like a lot of SHELLFISH allergies are, so cooking helps (most times I have been sick, it has been broiled platters- deep-fried doesn't seem to affect me).That also explains why mussels make me sick even though they are not a true salt water dweller and shrimp doesn't when they are.He also said he has had a patient DIE from this bacteria.Thanks a ton to the (nurse practitioner ?) at the clinic on Elbow... I was very sick, and the Cipro made me well(eventually, lol).

[DrRalph]

Hello Eric, welcome to the forum. From another Canadian site, the University of Guelph(?), and a host of food producers:

"Over the past decade, there has been in the Bahamas an increase in reported cases of Vibrio parahaemolyticus gastroenteritis, particularly during the summer months. This has been associated with the consumption of raw conch (strombus gigas). Conch (pronounced KONK) is a large marine gastropod, is not a filter feeder, and its intestines are removed prior to preparation for consumption. Government Agencies in the Bahamas have issued guidelines to minimize the risk of infection. These guidelines have been based on the knowledge that V. parahaemolyticus is halophilic, is a normal part of the marine environment, and the assumption that its presence on the conch represents surface contamination. We will not get the general public to refrain from consuming raw conch; it's a cultural thing, it IS delicious, and there are legions of folk who swear for its aphrodisiac qualities!
Generally, the recommendations have been simple: The preparation process must not at any stage include washing the conch in sea water; At the point of preparation, there must be a supply of fresh, running potable water; All food contact surfaces must be cleaned and sanitized frequently to minimize the risk of cross contamination; The conch must be washed thoroughly in fresh potable running water prior to preparation; Food handlers must attend a workshop on safe food handling, conducted by the Health Education Department, and must also obtain Health Certificates from the Department of Public Health as prerequisites
to obtaining vending permits. Bear in mind that conch is not a filter feeder, and it is not consumed whole; its digestive system is removed as part of the preparation process."

I apologize, this is getting very technical. But the punch line is: what some of you have related may not be an allergy but contamination, which may account for the irregularity of the symptoms. Eric's case sounds like "food poisoning," it responded to an appropriate antibiotic. Unfortunately, it just clouds the issue of "if I'm allergic to species A, will I be allergic to species B?" You won't know until you try it, and that's a weighty gamble. If you are indeed allergic to shellfish, I think the better part of valor is to avoid conch, as well as chocolate-covered ants and other insects (thank you, Pellucid, I wouldn't have made that connection.)

[SamFamAustin]

DrRalph you scared me on the "V" word for a minute. Then I figured you were not talking about V. vulnificus, which we would rather not discuss unless you want to.

But you're right, allergic reactions are caused by certain proteins, not by bacteria in the animal's digestive system. I don't think it's very well understood, except that some adults can develop an allergy later in life, seemingly for no specific reason. Let us know if you find some more scoop on the subject.

I woujld be just crushed if I developed fish/shellfish allergies. I eat seafood 5 times a week!

[ericinsc]

It is also possible to be super sensitive, or "allergic" to a bacteria, or, more specifically, to the toxins that that bacteria sheds (or excretes, as it were). I have had other reactions when I did not take antibiotics, and still got better. On Elbow it was worse, but I ate conch 3 days in a row. However , I think that was really an infection (after i got home ALL the skin on the palms of my hands died and peeled off.. that was what tipped off my GP), but the other times I was well within 2 days...

Who knows ?? I have a medical degree, and I sure don't. Allergies are wierd.

[NCDD]

now we have two people with medical degrees that are stumped :) You guys aren't helping me much LOL. Diane's doctors told us if she wanted to test her allergies to do it in a hospital parking lot :o Diane once ask her gastro guy, why I never got sick from eating stuff, his reply was "look at him, he could eat wall paper paste"