*If you are experiencing symptoms an allergic reaction, contact the appropriate medical personnel*
by Matt Pedersen
Move over, palytoxin, Mycobacterium, and a host of other zoonotic diseases; you’re not the only potential health risks in the aquarium hobby! Time to dive into a surprisingly prevalent health problem associated with bloodworms.
You may not have paid much attention to your fish-food labels, but let this be a reminder to read them thoroughly. Bloodworms, the bright-red mature larval stages of chironomid flies, are true powerhouses as a fish feed. Whether frozen or freeze-dried, they can be used to lure many reluctant feeders to “take the bait.” But if you haven’t been paying attention, you might not have noticed the note on the label that reveals that bloodworms also offer up the potential for strong allergic reactions for some aquarists who use them.
What the Science Says
The science behind bloodworm allergies points to the hemoglobins that give bloodworms their trademark bright-red coloration. These hemoglobins, which are powerful oxygen scavengers, are what allow bloodworms to thrive in the oxygen-deprived bodies of water they call home, but they are also what triggers an allergic reaction in some people.
One journal report suggests that hypersensitivity to bloodworm allergens exists in about 20% of people who are routinely exposed to them. Other studies reveal repeated connections between chironomid larvae and asthmatic reactions. These reports are often tied to environmental factors outside of the aquarium world among people who are in proximity to large natural populations of these midges, including: studies in Japan and Spain finding significant rates of allergic reactions in asthmatic patients, or the case of the delayed onset of hypersensitivity in an environmental surveyor after 10 years of exposure.
One report, covering the case of a 37-year-old fish-biology researcher, concluded, “With the increasing popularity of aquariums, allergy to chironomids may become less of a novelty and become something clinicians should be aware of when searching for the cause of a patient’s atopic symptoms.”
A View From the Aquarium Industry
Jason Oneppo, salesman and head of research and development for San Francisco Bay Brand (a distributor of frozen and freeze-dried fish bloodworms) for the past 17 years, noted that his company is actively working on a revised bloodworm allergy document, to be published in the near future.
From a draft of the report shared with Reef to Rainforest editors: “If you find yourself allergic to frozen bloodworms, freeze-dried bloodworms will cause similar reactions. As moisture is removed from bloodworms in the freeze-drying process, these worms become brittle and can easily turn into a fine powder. Such powdered, lightweight bloodworm particles can become airborne, and inhalation of these particles can cause an allergic reaction similar or greater than touching frozen bloodworms.”
Oneppo also added some personal insights: “We’ve had allergy warnings on our frozen and freeze-dried bloodworm labels for as long as I’ve worked here. We’ve also had allergy warnings on our other freeze-dried labels for at least 10 years. Now, all our freeze-dried products have allergy warnings, even items that don’t require it when frozen.”
A cautionary thought from Oneppo: “[Once you’re allergic to bloodworms, I believe] each reaction gets worse; best to get them out of your house.”
What to Watch for
Multiple reports suggest that cross sensitivity could occur; in short, if you’re allergic to things like mites or cockroaches (which have similar allergens), you could have an increased risk of hypersensitivity to bloodworms.
San Francisco Bay Brand’s draft report includes the following possible symptoms of allergic reactions: sneezing, skin rashes, runny nose, or itchy eyes. Additionally, more pronounced asthmatic reactions could occur.
In all cases, should you experience any of these symptoms, it is strongly recommended that you discontinue feeding bloodworms.
The idea of a bloodworm allergy may seem far-fetched; many aquarists have never even heard of it. But when I reached out to contacts and their friends, it quickly became apparent that this allergy is not rare, not by a long shot. Here is just one of many stories I received.
Derek Wheaton, a professional fish photographer at Enchanting Ectotherms, and Senior Field Biologist & Hatchery Technician at Conservation Fisheries in Knoxville, TN, shared that he has a strong allergic reaction to bloodworms. “I was feeding a tank on the top row at work and got the business end of a tiny, unfortunate splash when I squirted the baster into the tank. I avert my eyes when feeding any tank above my head now. But skin contact [with bloodworms] gives me raised welts, itching and burning, and within 3-5 minutes of skin exposure, I’m sneezing my brains out and my eyes will swell shut if I don’t smash some Benadryl. I always wear nitrile gloves whenever I’m working with the stuff. A full hazmat suit would probably be ideal though.”
It bears repeating: *If you are experiencing symptoms, please contact the appropriate medical personnel*
Bloodworm allergies are a bit more prevalent than one might have thought, and they can range from a mild nuisance to rather scary, debilitating reactions. While we’re unaware of any deaths resulting from bloodworm exposure, anaphylactic shock is one of those things you perhaps don’t want to risk.
We’d Like to Hear from You
Wheaton’s story is just one of several we received, but we’d like to hear from you as well!
AMAZONAS Magazine is conducting a simple survey of our readers to get a larger sampling of data, which we will share in a future update. Whether you have a bloodworm allergy or not, your responses are very valuable. We invite you to participate in this 3-to-12–question survey. It will only take a minute or two of your time.
Fishing for Allergens: Bloodworm-Induced Asthma – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2877067/
Chironomid midge allergy: https://www.ncbi.nlm.nih.gov/pubmed/1567285
Nationwide intradermal test with chironomid midge extract in asthmatic children in Japan: https://www.ncbi.nlm.nih.gov/pubmed/2241583
Studies of bronchial asthma induced by chironomid midges (Diptera) around a hypereutrophic lake in Japan: https://www.ncbi.nlm.nih.gov/pubmed/9105523
Hypersensitivity to chironomid larvae [Spain]: https://www.ncbi.nlm.nih.gov/pubmed/9777536