Stings, Bites, Rashes, oh my!
With the increasing popularity of Triathlons, hundreds of thousands of athletes have flocked to the previously obscure sport of open water swimming. This activity has an entirely different set of medical risks from pool swimming. As a dermatologist and an open water swimmer, I have treated these problems and experienced them first hand.
The number one question I get regarding open water swimming is “aren’t you afraid of getting attacked by an alligator?”. My answer is, “sure, but I would also like to win the Powerball, and I’m statistically more likely to do that than to have an alligator encounter.” I do know a person that did get attacked by an alligator, but I also know someone who won the Powerball lotto, so there you go. Statistically speaking you are 60 times more likely to die in an automobile accident driving to a lake swim than you are to be killed by a gator during the swim. If you ride your bike 80 times more likely, and if you parachute to the swim 640 times more likely (yes, I have had someone parachute into my backyard for a swim). If you are swimming in the ocean substitute the word shark for gator in the above paragraph and you would have nearly the same scenario.
Now other things are lurking in the water more likely to bite you than gators or sharks. I have personally been bitten by fish, turtles, snakes, ducks and even stingrays. In most of these cases, there was a significant poor judgment factor on my part, except for the duck bites. The ICD10 code for duck bites is W61.61XD, in case you didn’t know. Fortunately, these animal bites require minimal medical attention, and the scolding by the spouse is far worse than the actual injury.
The number two question is “What about brain-eating amoeba?” The freshwater infection by Naegleria fowleri is a tragic medical condition with over a 95% fatality rate. Even with the amoeba being ubiquitous throughout Florida’s lakes infection is rare, with fewer than 100 US reported cases in the last four decades. It’s hard for a journalist to pass on a story with a headline “Brain-eating Amoeba,” therefore virtually all cases get national exposure making risk appear higher than reality. Amoebic meningoencephalitis is associated with forced entry of warm, stagnant water into the sinuses, with passage of amoeba through the cribriform plate. The risk of infection per water exposure is one in 128 million. So, if you do 128 million open water swims you are pretty much screwed. I recommend swimmers wear a nose clip when the water gets above 82 degrees and avoid activities that might force water into the sinuses such as jumping off a dock feet-first. Although, I have not found any reported cases of open water swimmers/triathletes contracting this through races or training.
If you are an ocean swimmer, there are more opportunities to gets stings than bites. I do not know of any serious open water swimmers that have avoided being stung at least once. Stings are a rite of passage for the sport. Jellyfish encounters are quite common, and I have been in races where over 90 percent of the participants suffered stings. Jellyfish stings can range from being a minor annoyance to lethal as in the case of box jellyfish. Fortunately, the Florida coast does not harbor deadly types of jellyfish, but anaphylactic shock is always a possible risk.
Man-O-Wars are not jellyfish (they are siphonophores in case you wanted to know), and in my experience, they are more painful. Identified by their purple or blue pneumatophore (sail) they float on the surface but have tentacles that can extend several feet from the body. The tentacles tend to wrap around a swimmer’s extremities and stick to any skin they contact. A popular urban myth is the best treatment for man o war stings is to urinate on them, but this only works on reality television shows. Other anecdotal therapies abound; such as application of ammonia, alcohol, meat tenderizer, freshwater, cold packs, etc.…Not only are these treatments ineffective, most will worsen the stings. What does work, science-based and published, is the application of vinegar followed by heat at 45 degrees centigrade. Vinegar stabilizes the nematocysts, so they don’t fire off, and heat may denature some of the venoms. Apply the vinegar before attempting to remove tentacles with tweezers.
Other sea organisms can sting swimmers, although jellyfish stings are the most common. Fire coral can accidentally be brushed against leaving behind scrapes while injecting painful venom. There is also the possibility of stepping on sea urchins or stingrays. Application of heat is the treatment of choice for these injuries and in the case of urchins or stingrays removal of the spine or barb.
Two rashes affecting open water swimmers are seabather’s eruption and swimmers itch, which occur following swimming in salt water and fresh water respectively. Seabather’s eruption appears as pruritic inflammatory papules in the swimsuit coverage area. The cause is larval forms of thimble jellyfish and sea anemones; these pinhead size organisms get entrapped in the swimsuit. When the swimmer exits the water trapped larvae fire off nematocysts in response to toweling, drying, or freshwater rinsing. Vinegar rinses before removing the suit may help. Swimmers itch (cercarial dermatitis) follows freshwater swimming. Its distribution is inverse of seabather’s eruption affecting only exposed areas. The itch is a hypersensitivity reaction to larval schistosomes burrowing in the skin. Usually, this parasite’s life cycle is waterfowl to snail to waterfowl. Larva mistakenly burrows into human skin, but do not survive creating an allergic reaction. Larvae occur in higher concentrations in shallow water, and it helps to towel off after exiting the water immediately. Treatment is palliative with topical corticosteroids.
For anyone who is itching for a swim, you are in luck. I began hosting a daily lake swim at my home in 1989. The swim has grown from a handful of swimming friends to thousands worldwide. Eponymously known as “Lucky’s Lake Swim” it is ranked by the World Open Water Swimming Association as one of America’s top 100 swims (not too shabby as there are over 4000 open water swims in the USA) additionally the Orange County Historical Society has proclaimed the swim a historic central Florida event. I encourage all swimmers to join me. There is never a charge to swim with me, but it is BYOGK (bring your own gator knife).
By Lucky Meisenheimer, M.D. and John Meisenheimer, VII