Perilous Waters
Want to know what animal is called the most venomous in the world? If pee is an antidote and how pantyhose makes swimming safer? Listen to find out!
This is the Pick Your Poison podcast. I’m your host Dr. JP and I’m here to share my passion for poisons in this interactive show. Will our patients survive this podcast? It’s up to you and the choices you make. Our episode today is called Perilous Waters.
Want to know what animal is called the most venomous in the world? If pee is an antidote and how pantyhose makes swimming safer?
Today's episode starts on the beach. You're lying in the sun, half asleep, sticky with sunscreen. You’re hoping to finally get some rest. Also, you’re optimistic this vacation will go better than your last attempt in Thailand. You sit up to adjust the umbrella, keeping yourself in the shade and out of direct exposure to UV rays and melanoma. There’s commotion in the water nearby. A lifeguard with a flotation device runs down.
You’re tempted to roll over and pretend you didn’t see anything except the tropical cocktail being delivered to the people nearby. But you don’t. Several swimmers drag a teenager out of the water and onto the sand, flipping him over on his back. He’s motionless, either unconscious or dead. Maybe a drowning or near drowning. The bystanders are looking and doing nothing. It’s clear no one knows what to do. You get up and run over, automatically putting your fingers on the boy’s neck, as you drop to your knees, to check for a pulse.
Nothing.
He looks about 16 years-old. You adjust your fingers.
Nothing.
You say, “No pulse, start CPR.” Aloud, out of habit, though there's no one to follow those instructions except you and maybe the lifeguard. The lifeguard’s eyes widen in shock, he doesn’t look much older than the patient. You interlock your fingers, put your hands over the sternum, and start compressions. The lifeguard radios for help. To your relief, sirens wail in the distance almost immediately. You ask if there’s a defibrillator, he says no.
You’ve done 30 chest compressions. You tell the lifeguard to give two rescue breaths. The song Staying Alive plays in your mind, just like every time you do CPR, a remnant of basic CPR classes. You keep the rate of compressions synced with the beat of the song to give approximately 100 per minute. Pausing again for two breaths, you look at the rest of the patient. No obvious external signs of trauma. His skin is red, not blue like you’d expect if he’d drowned. You notice his legs, covered in a crosshatched pattern of red welts.
You now have a strong suspicion about what's happened. Question number one. What is the likely cause of this patient's cardiac arrest?
Blue ringed octopus
Man o’war jellyfish
Stonefish
Box jellyfish
Answer: D. This is consistent with box jellyfish envenomation. Box jellyfish have been called the most venomous animals in the world, though a number of creatures are vying for the title. A quick aside about the difference between envenomation and poisoning, a pet peeve of toxicologists, so I hope you know the difference. Venom is injected. Via fangs, stingers or spines, for example. Snakes and jellyfish envenomate. In contrast to poisoning after eating pufferfish, since the fish didn’t bite or inject you.
You restart CPR and notice part of a tentacle attached to the boy’s right leg. Question # 2, what do you do next?
Ask a bystander to pee on it
Pour vinegar on it
Ask someone to pour bottled water on it
Answer B: Ask the lifeguard for vinegar. Vinegar may inactivate the venom and should loosen the tentacle from the leg to prevent discharge of more toxin. More details on this as well as the other options in a bit.
The sirens get louder, the medics arrive, scoop up the patient and take him to the nearest emergency department, only a few blocks away. Of course, you’re here on vacation, not practicing medicine in Australia, but this is a fictional case so let's pretend we are taking care of him in the ER. The nurses continue CPR, you order epinephrine and usual advanced life support measures.
Question number three. Which medicine should you give next?
Box jellyfish antivenom
Magnesium
Nitroglycerin
More epinephrine
Answer A: There is an antidote, box jellyfish antivenom, approved for use in Australia. You order it. While we're waiting for it to be administered, let's talk in some more detail about what's going on with our patient.
This is a severe case of box jellyfish envenomation. There are at least 50 different species of box jellyfish. This envenomation is caused by the Chironex fleckeri species. The vast majority of exposures result in mild symptoms, but severe envenomation, as with our patient, is a life-threatening emergency. First aid treatment consists of applying vinegar to reduce discharge and potentially inactivating the venom. Interestingly, if you go to a beach in Australia, you might see a vinegar station. Something like a post with a sign and a container of vinegar. Most patients are fine with supportive care and pain control.
For severe cases antivenom is indicated. It’s been approved for use since the 1970s. Surprisingly, there’s a lot of debate about its efficacy. Patients have died despite getting antivenom and survived without it. One study in rats really highlights the issue, showing if the box jellyfish venom and antivenom were given at the same time, the animals survived. The antivenom does work to bind up and inactivate the toxins. However, when the venom was given first, the animals died. This is because the toxins work at lightning speed, any antidote given after exposure, as in real life, is too late.
“Time for a pulse check,” the nurse says, interrupting your thoughts. You put your fingers on the patient’s neck and feel a weak, but steady beat. You check the monitor to make sure it’s not your own pulse throbbing in your fingers. It shows normal sinus rhythm. A cheer and a few high fives go around the room.
“Do you still want the antivenom,” she asks, holding up the vial that just arrived from the pharmacy.
Is there any downside to giving it? A few. Allergic reactions are rare, but can occur. In this case it’s a sheep-derived product, those with sheep allergies are at risk. More common is serum sickness. This is an immune hypersensitivity reaction causing fever, rash and joint pain. We always warn patients about risk, it also occurs with snake antivenom, because the reaction is delayed up to 2 weeks after exposure. It can be treated with steroids. In this case, given the severity of the envenomation, the benefits of administering outweigh the risks.
The dosing recommendations are as follows: 1 amp of antivenom for pain refractory to opioids. Three amps if the patient is hemodynamically compromised, ie hypertension or hypotension, etc. Six amps for cardiac arrest. You can give more if needed.
About 80 deaths are attributed to C. fleckeri envenomation, though this number is likely an underestimate given the difficulty in making the diagnosis. How does box jellyfish venom work? The exact mechanism isn’t known, but it’s believed to cause pore formation in cardiac cells. Essentially punching a hole in heart cell membranes, which as you can imagine, isn’t good. Electrolyte disturbances and sudden cardiac arrest is the result.
In 2019 researchers announced they’d found an antidote to box jellyfish venom that worked topically on the skin to stop pain and prevent tissue destruction in mice. This was announced with a lot of fanfare by the news media; we’ll see if this develops into a new drug.
Our patient wakes up and starts moving. A great sign. You call the ICU and get him admitted.
There is a second type of serious jellyfish envenomation. I’ve been confused in the past, because they have some similarities and it’s also caused by box jellyfish. A patient with this scenario might present as follows. They go for a swim in the ocean, get out and rest on the sand. Thirty minutes later, they have sweating, severe body pain, including abdominal pain and muscles aches. They feel like they are dying.
This is called Irukandji syndrome, it’s a more general systemic problem. Box jellyfish antivenom does not seem to help these patients. How do you tell them apart? The distinguishing features are time of onset and skin findings. Irukandji syndrome has a delayed onset, meaning about 20 minutes to a few hours after exposure, unlike the instantaneous onset of C. Fleckeri venom. The Queensland Ambulance Service describes C. Fleckeri stings as “savage, multiple whip welts”. But patients with Irukandji syndrome often don’t know they’ve been stung and don’t have jellyfish stings.
So how do we really know Irukandji syndrome is caused by box jellyfish? Thanks to a man name Jack Barnes. The syndrome itself was described as early as the 1930s and named after a local Aboriginal tribe, but cause of the syndrome remained a mystery until 1961. Barnes, an Australian physician and ex-military commando decided to prove it was caused by a box jellyfish. He did so by stinging himself, his 9-year-old son and a local lifeguard. All three developed Irukandji syndrome. They recovered in several hours, after treatment with pain medicine. The poor kid wasn’t even allowed to skip school the next day. The jellyfish Barnes used to envenomate himself, a Cuboza species, was named Carukia barnesi after him.
Since then, many other species have been found to cause Irukandji syndrome. It resembles a catecholamine surge or a sympathomimetic syndrome with high blood pressure and heart rate, sweating and muscle cramping. It causes abdominal pain, anxiety and agitation. It can progress to pulmonary edema, or fluid in the lungs and cardiac arrest. However, only two people have died from this in contrast to C. fleckeri envenomation. Both of the deaths were due to intracranial hemorrhage, presumably as a result of high blood pressure.
Irukandji syndrome has since been reported around the world, in tropical waters, including Thailand, the Caribbean, Hawaii and Florida.
I’m always surprised by just how small box jellyfish are in size, given their outsize effect on humans. Patients with stings have welts from long tentacles, often covering their legs. Astonishingly, the box jellys bodies are only 1-2 cm, the size of a sugar cube or a fingernail. They are transparent, and therefore almost invisible. However, their tentacles stretch up to a meter or three feet long. Notably, stings can occur within anti jellyfish net swimming areas, because they are so small they fit between spaces in the nets.
Jellyfish have a really cool system to envenomate patients and prey. Their tentacles are lined with cells called nematocysts. Inside these amazing cells is a barb, called an operculum. It’s coiled up in the cell and covered with venom. When stimulated, it shoots out, envenomating prey. Also, I thought some listeners, might want to know this fascinating biological fact. The box jellyfish has only one opening which they use as both a mouth and an anus. Eww.
Question # 4. Use of what can prevent jellyfish stings?
Vaseline
Pantyhose
Wetsuits
All of the above
Answer: D all of the above. Wetsuits create a barrier. Vaseline on exposed areas seems to reduce the likelihood of stings. And in 1972, Jack Barnes demonstrated pantyhose worked. So if you swim in pantyhose, you should be safe.
The cause of Irukandji syndrome is uncertain. Theories include a severe stress response with catecholamine release, like a sympathomimetic syndrome due to cocaine or meth. Another theory suggests damage to cardiac cell membranes via pore formation, leading to toxicity and damage. For unknown reasons, outbreaks seem to occur in localized clusters. For example, in 1985 in Australia, 36 stings occurred over a few hours on Christmas Day at a single beach. No stings were reported at nearby beaches.
Treatment of Irukandji syndrome is supportive. Specifically, opioids for pain, benzodiazepines for anxiety. Magnesium may be useful, though there is some debate, and nitroglycerin for pulmonary edema.
A little more about treating painful stings. As I said earlier, we’d apply vinegar. I’ve always found the data on treatment of marine envenomations confusing and conflicting. Pick a treatment option and, frustratingly, you’ll find several studies suggesting it helps and just as many showing it hurts. Part of the difficulty is we never really know what stung the patient in the ocean, and findings in the lab may not translate into real life conditions. Vinegar is widely recommended; thus, the beach vinegar stations I mentioned. It’s believed to reduce nematocyte firing. However, there is animal data suggesting it might increase the amount of venom released by those that have already fired by 50%. While this study hasn’t changed recommendations, don’t be surprised if we have new advice in the future.
Hot water may help, but it has to be at 110F or 43 C, so make sure you don’t burn your patient after they’ve already suffered a jellyfish sting. Fresh water increases discharge of venom, so if you don't have vinegar, seawater is better than bottled water. I’d love to know where the myth of peeing on stings to reduce pain comes from, my guess, it was a hold my beer situation. For the permanent record, no, it doesn’t help.
Warmer ocean temperatures, as seen in Florida during El Nino events, causes jellyfish tentacles to grow longer. Meaning more nematocytes and increased toxicity. On the other hand, heavy metal exposure, pollution, reduces nematocyte discharge and may decrease toxicity of the venom as well. Its remarkable we humans can impact marine life so directly. It’s unfortunate we’re so careless about doing so.
Our patient wakes up and returns to normal with no neurological sequela, thanks to immediate bystander CPR and good medical care. This is a fictional case, as are all our cases, to protect the innocent. But it is based on real poisonings that occur periodically. After he’s released from the hospital, you get to enjoy a few uneventful days at the beach, before your vacation ends. Beach and sun only for you, no swimming, since you don’t want to end up with a painful sting somebody tries to pee on or worse, an ICU stay.
Question #5 is today’s Pop Culture Consult. Queen Latifah’s character in what movie is killed by aggressive jellyfish?
The Little Mermaid
The Abyss
Sphere
Jaws
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