Floridians need to be aware that jellyfish can not only be a source of an unpleasant sting, but also of allergic reactions. In fact, life threatening allergy (anaphylaxis) was first described in 1901 by two scientists; Charles Richet and Paul Portier who were studying jellyfish. They began their studies at the behest of Prince Albert of Monaco who was an avid oceanographer. He asked them to study the sting of the Portuguese man-of-war. They used the venom from both the man-of-war and the sea anemone in dog studies.
Because the concept of vaccination was new to science, they wondered if they could “vaccinate” dogs with the venom to build up protection. Unexpectedly (because they used too large of doses) and to their dismay, the second injection caused some of the dogs to die suddenly, because they failed to provide “phylaxis” (now called prophylaxis). They called the events aphylaxis (eventually termed anaphylaxis) meaning “against” “protection”. As a dog lover I’m sorry for the dogs, but I guess it would have been worse if they had experimented on the prince.
Jellyfish belong to the phylum Cnidaria which refers to the cnida, a specialized explosive organelle that causes stings. The cnida produce a variety of proteins which can lead to allergic sensitization: congestin, hyaluronidase, collagenase, proteinase, hypnotoxin, thalassin, nuclease, and phosphatase.
There are 10,000 species of jellyfish and their numbers are increasing due to global warming. The most common jellyfish allergy is skin allergy either immediate or delayed. The immediate reaction is hives that occur in addition to the “stings”. The hives respond to antihistamine therapy but the stings do not. The delayed reaction is akin to poison ivy allergy in that an itchy blistering develops several days after the immediate stings. This type of allergy responds best to steroids, either topical or oral.
The next most common reaction is food allergy reaction with itchy rash and GI symptoms after ingesting jellyfish. In some cultures, the umbrella (outer portion) of the jellyfish is a common food.
Anaphylaxis is the rarest form of allergy but can be life threatening. Most cases occur in people with frequent and repeated contact with jellyfish especially surfers and open water swimmers.