Tox and Hound – Some Like It Hot

by Meghan Spyres

The holidays are over and it’s time for that long stretch of thankless winter before spring is here again. Sounds like the perfect time to plan a trip somewhere tropical! Which also makes it the perfect time to review one of my favorite topics: marine envenomations.

Although we typically think of the most dangerous (and coolest) marine envenomations as occurring in the Indo-Pacific areas, including Australia, there are many noteworthy envenomations right here in the US. You’ll have to wait for warmer weather to see them, but you can look forward to the stingray on the Pacific coast and the Portuguese man-of-war in the Atlantic. And don’t forget about our aquarium enthusiasts; you never know what toxic exotic marine dwellers they might be hiding.¹

So how do we approach marine envenomations here in the US? The first thing is to try to figure out what animal is involved, although this is often easier said than done. If the patient got a good look, great. But we’re not usually lucky enough to receive such packaged histories. Fear not. The circumstances of the envenomation, the geographic location, and the envenomation syndrome can all help, at least somewhat. Let’s go through a couple of scenarios to help guide you through envenomations you may encounter while practicing here in the US.

Case, the First.

A 30-year-old guy, newly transplanted from the east coast, is enjoying the Southern California sun on the beach with a bunch of dudes (ok, it’s my brother, last summer). He’s wading out for a swim, likely after drinking a few beers, keeping his feet on the sand because, you know, he’s kind of tired from those beers. Suddenly, he notices the sand moving beneath his feet and feels a very sharp stabbing sensation to his heel. He exits the water and the pain just keeps intensifying. By the time he’s home, a few minutes later, the pain is excruciating, but the wound isn’t too impressive. When this guy now presents to your ED with severe pain, what should you do? And what aquatic monster attacked my brother?

Good news: The best way to manage pain for almost all marine envenomations in North America is the same. And it’s not vinegar, or worse urine, as you may have been led to believe. It’s hot water! And this applies to North American jellyfish too (more below). This is due to the heat-labile nature of the venoms; they get deactivated at high temperatures. Before you have even ascertained what struck this poor guy, you likely want to immerse the affected area in hot water for pain relief. How hot is hot? Most sources recommend water to be up to 45°C (studies use water ranging 40-45°C).^2,3 Practically speaking, to do this, you can use hot water from the tap, as hot as is tolerated. Make sure you don’t burn the patient, especially if you have used any adjunct agents like local lidocaine (Pro Tip: make sure a non-anesthetized body part is also in the water). Submerge the affected area in the hot water for about 30 minutes or until the pain is relieved.

The description of this envenomation, along with the location and circumstances suggest this is likely a stingray, quite possibly the round stingray (Urolophus halleri) which inhabits southern California oceans. Severe pain is characteristic for stingray envenomations but, luckily, systemic symptoms are uncommon. In addition to treating the pain, you should assess for traumatic injuries including tendon and arterial lacerations (let us not forget the late great Steve Irwin). Imaging for foreign bodies is recommended (x-ray or ultrasound is a good starting place) as the retro serrated tail can leave barbs behind.^4,5 Prophylactic antibiotics against Vibrio species are recommended as delayed infections are not uncommon.⁶ Ciprofloxacin, doxycycline, and trimethoprim-sulfamethoxazole are common agents used. If the stingray barb didn’t take out the Achilles tendon, maybe the fluoroquinolone will . . .

Case, the Second.

An amateur diver returns from a trip to the Gulf of Mexico complaining of feeling generally unwell with persistent pain to her foot where she believes she was stung by something while diving around a coral reef. During one of the dives, she accidentally stepped on the reef and noticed a sharp thorn stuck in her foot. She thought she removed it, but a piece may have broken off. What should you do?

Although exposure to fire coral (Millepora genus) is possible, this story sounds most like an envenomation from an echinoderm, such as a sea urchin (Echinoidea class) or the crown-of-thorns sea star (Acanthaster planci). Both can cause immediate pain, and systemic symptoms are also possible, including hepatotoxicity.^7,8 More commonly, retained spines cause local reactions including granulomas, arthritis, tenosynovitis, and tattooing of the skin.^9,10 For this patient, you would want to obtain imaging to look for that retained spine. If found, the spine should be removed to prevent granuloma formation, possibly by a surgeon. For deep wounds, prophylactic antibiotics (again against vibrio) should be given. Hot water works for venom-related pain for echinoderms too, however, the delayed pain in this patient may more likely be due to infection or inflammation from the retained spine.

Case, the Third.

A fisherman in San Diego sees a yellow snake in his nets. He grabs it (please don’t do this) and is struck on the hand. He takes a picture of the snake and brings it in when he presents to the ED. Other than some pain at the bite site, he is asymptomatic. What should you be looking for?

Luckily, in this case, the identity of the animal is clear: this is a yellow-bellied sea snake (Pelamis platura). Although typically found in more tropical Indo-Pacific oceans, they have recently been seen off the coast in southern California. They aren’t aggressive and tend to bite only in defense when grabbed or stepped on. So please, don’t do that. Interestingly, their venom contains a potent neurotoxin (these are elapids after all) and myotoxins.¹¹ Clinical toxicity can be severe. You want to be on the look-out for myalgias, rhabdomyolysis and muscle weakness, including respiratory paralysis. Ptosis can be an early finding; however, even asymptomatic patients should be watched for 8 hours as delayed presentations are reported.^12,13 No one wants to stop breathing out on a fishing boat. These patients should also get labs to check electrolytes and creatinine kinase along with a urinalysis to look for blood.

Case, the Fourth.

A woman is swimming in the ocean off the coast of Florida when she feels something brush the side of her arm. She has immediate burning pain to that arm. By the time she gets to the ED, she is complaining of severe arm pain, and you notice a linear, erythematous rash that is starting to develop some bullae. She also describes a weird tingling sensation in that arm and on her exam you note it to be somewhat weaker than the other.

Given the location and the clinical presentation, this envenomation is suspicious for the Portuguese man-of-war (Physalia physalis). During a jellyfish sting, the victim rarely gets a good look at the animal, and management decisions are often made based on the geographic location. As discussed above, hot water is the go-to treatment for pain control in North American and Hawaiian cnidaria envenomations, including the man-of-war.³ There is some controversial data, however, regarding acetic acid (vinegar) for P. physalis. A few low-quality basic science studies show vinegar reduces nematocyst discharge.¹⁴ Additionally, a single clinical study is cited as demonstrating pain reduction with vinegar, however, this is for the Australian bluebottle, not the Atlantic Portuguese man-of-war.¹⁵ When vinegar is used for P. physalis, the majority of the data show increased nematocyst discharge and failure to reduce pain. More importantly, hot water immersion results in good pain control.³ Although most North American jellyfish envenomations are mild (scyphozoan class), P. physalis (hydrozoa class) can cause significant systemic symptoms including myalgias, limb paralysis, renal failure and cardiovascular collapse in severe envenomations.² Patients with systemic symptoms should be observed until they are improving, as rare deaths have been reported.

A couple of general things to remember: we give all these guys tetanus updates, and know that allergic reactions can occur.

Quick Review:

• Hot water is the first line treatment for pain for jellyfish envenomations in the US. This is also true for stingrays, sea urchins, and crown-of-thorns sea stars.
• Don’t forget to look for foreign bodies in the appropriate cases and give prophylactic antibiotics covering vibrio for high-risk cases including stingrays, sea urchins, and crown-of-thorns sea stars.
• Make sure you look for rhabdomyolysis in sea snake envenomations and observe for at least 8 hours to catch those delayed cases.
• Finally, rely on the geographic location and the circumstances of the envenomation in addition to the clinical presentation to help you figure out the diagnosis.

Now that you’ve seen a sampling of serious US envenomations, you may not want to travel to those exotic beaches where the consequences of envenomation can be much worse. No? Still want more? Stay tuned to future posts where we’ll go through all the ways swimming in Australian ocean waters is a death mission.
Jellyfish by Zhi