Hitchhiker
Want to know what hitchhikers have to do with toxicology? Exposure to what animal has been mistaken for a drug of abuse? What substance costs $40 million dollars per gallon?
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 patient survive this podcast? It’s up to you and the choices you make. Our episode today is called Hitchhiker.
Want to know what hitchhikers have to do with toxicology? Exposure to what animal has been mistaken for a drug of abuse? What substance costs $40 million dollars per gallon? Listen to find out.
Today's episode starts with a phone call. Your friends name pops up on the screen and you answer, expecting to hear about her weekend trip to an expensive spa. Except, she's crying so hard you can barely understand what she’s saying. You manage to gather she’s on the way to the Emergency department, but can’t understand anything else. You tell her you’ll meet her there.
You rush inside, relieved she's already in a room and under the care of a colleague. You sit in the bedside chair, for relatives, which feels weird. Your friend’s face is streaked with tears, and she’s curled up in a fetal position on the stretcher, but at least she’s no longer crying, thanks to a dose of pain medicine. She’s 33 years old, and an otherwise healthy marathon runner.
What happened?
She says the spa in Arizona was amazing, she got facials, massages, did sunrise yoga, hiked and ate delicious meals, arriving home late last night on an uneventful flight back to New York City. The symptoms started with pain in her hand, associated with numbness and tingling moving up her arm. It became excruciating and now involves her whole body. Her lips feel numb. She's shivering and you can see her muscles shaking.
The monitor shows her vital signs, temperature 98.5F or 36.9 C, blood pressure mildly elevated at 150/70, heart rate 120 beats per minute, RR 20, pulse ox 100% room air. As you sit there, every 5 or 10 minutes she has more severe spasms, resembling a seizure, though unlike a seizure, she’s awake and talking during.
Was she poisoned at the spa? By the healthy food? I know we have some crime writers listening, I’m sure they’ve already generated several potential plot points. Was there mercury or heavy metals in the facial? Did she drink essential oils instead of smelling them? A delayed onset snakebite from a hike?
Light-hearted joking aside, something serious happened. You’ve only been there for thirty minutes and her condition is worsening. She’s no longer looking at you, or anything else in particular, instead her eyes are roving back-and-forth. Continuously, like she’s watching a very disorganized tennis match. Uh no. This is called opsoclonus.
What causes this? First, it’s not a vision problem, but a sign of neurological problems in the brain, essentially representing disorganized brain circuits, which is about as bad as it sounds. It can be a paraneoplastic syndrome, meaning associated with an underlying tumor. It’s also caused by severe autoimmune disease like lupus cerebritis, ie brain inflammation, and infection like encephalitis, from West Nile virus for example. Yikes. This is not a list anyone wants to hear, a mercury infused facial might be better, and definitely not one you want to think about for a friend. Does she have one of these? Opsoclonus is associated with advanced disease in all of the above cases, none cause it in the span of a few hours. This suggests, you guessed it, a toxin.
Question #1. We’re starting off with a tough one. What toxins cause opsoclonus, these roving eye movements?
A. Lithium
B. Serotonin (ie serotonin syndrome)
C. Scorpion envenomation
D. Cocaine
E. All of the above
Answer: E. All of the above.
No one hopes to be poisoned, but if I ever develop opsoclonus, I hope it’s from a toxin. Why? Those causes are generally treatable and reversable, unlike some of the severe neurologic causes.
What happened to your friend? Looking at this list, she doesn’t do drugs and doesn’t take any medicines, ruling out lithium, cocaine and serotonin syndrome, caused by medicines like antidepressants. She was just in Arizona, home to scorpions. Opsoclonus is especially associated with bark scorpions native to Arizona, and her other symptoms, pain and muscles spasms are classic for scorpion envenomation.
Wait a minute did I hear you say, she was fine until she got back. Excellent point. Can you have delayed onset symptoms? I mentioned snake bites a minute ago. Rattlesnake, and other pit viper envenomation symptoms start immediately, at the worst developing over a few hours. In contrast, elapid bites can have delayed symptoms, up to 12 hours. In the US, these are coral snakes, causing neurological symptoms like weakness and paralysis. In other places cobras and mambas. Can scorpion stings also cause delayed onset symptoms? No. So we should rule it out? But I just said her symptoms are classic.
This brings us to a rare, but famous, issue in toxicology. Hitchhikers and stowaways. Not the serial killing kind, but the venomous kind. Scorpions like cool dark places, suitcases for example. Patient have returned home uneventfully, then been stung after unpacking the suitcase where the scorpion unintentionally stowed away. So even if you work in a big city like New York, or a cold place like Canada, you might get a call about an envenomation from a non-native animal. It could be someone’s exotic pet, but it might be a stowaway from their vacation. Dry cleaners have been stung by creatures hiding in the laundry pile too. It’s not just scorpions, snakes and spiders can travel.
Your friend was fine until she decided to unpack her suitcase a few hours ago, when she reached in, the hitchhiker scorpion stung her. She had the presence of mind to slam the suitcase shut and zip it, so there isn’t a rogue arthropod roaming her house or her neighborhood but she didn’t stop to identify it. That’s ok, based on her symptoms and the spa’s location you can guess it was an Arizona bark scorpion, Centruroides exilicauda.
Confirming your suspicion, she has a single puncture wound on her arm with mild redness and swelling. You tap the wound. Some envenomations cause a positive tap test.
Question #2. What do you expect if this is a scorpion sting?
A. bruising when the skin is tapped.
B. Increased reflexes when the skin is tapped
C. increased pain
The answer is C, the tap test is when pain and tingling increase over the area tapped. It's not true for all scorpions and it doesn't work in every case, but if it's positive it certainly suggests a scorpion. She shrieks when you tap it, so def positive.
Are you asking why we need a test to figure out if somebody is envenomated? Shouldn’t it be obvious? Good question. In reality, the history may be lacking. If it’s dark, the victim might not see what stung them. Scorpion wounds are very small and not always visible. Children can be particularly difficult. If they aren’t able to talk, and an adult doesn’t see what happened, it can be a medical mystery.
Question 3. Your friend needs an antidote.
A.True
B. False
Answer A. True. There is an antidote for Centruroides scorpion stings call Anascorp. It’s made in Mexico from 4 different types of Centruroides venom and it’s an antibody fragment, like snake and digoxin antivenom.
Who gets antivenom? It depends on the severity of the symptoms. We use a grading scale of 1-4, it’s typically administered to patients with a three or four. Grade 1 is local symptoms, mild pain at the site of the sting. Grade 2 is pain moving up the extremity, it can include perioral numbness around the mouth. For both of these, pain medicine is usually sufficient and antivenom is unnecessary. Grade 3 is systemic symptoms, either neuromuscular change like whole body pain, restlessness, myoclonus ie muscle twitches and jerking that can be mistaken for a seizure. Or cranial nerve symptoms like opsoclonus, hypersalivation, speech problems and tongue fasciculations. Grade 4 is both cranial nerve dysfunction and neuromuscular changes.
How does scorpion venom work? Like snakes, it’s a combination of toxins, including most notably neurotoxins. We have a lot to learn about exactly how the venom works. In bark scorpions its thought venom open sodium channels in the neuromuscular junction, causing repetitive depolarization, meaning release of excessive amounts of neurotransmitters like acetylcholine, epinephrine and norepinephrine.
Lots of complications can occur, we can’t get into them all here, it would take all day because different species around the world cause different symptoms. But I do want to mention some less common effects. Autonomic storm, is one, it’s a high heart rate and blood pressure from release of epi and norepi. Essentially a fight or flight response from the envenomation, rather than the circumstances. Quite frankly if I’m ever up close and personal with a scorpion, I'm going to experience an autonomic storm just from looking at it.
There are reports of myocarditis, inflammation of the heart muscle, arrhythmias, and even heart attacks. Coagulation problems, ie bleeding disorders, hemoptysis, coughing up blood, ARDS, acute respiratory distress syndrome and pulmonary edema. Strokes, even in children, and seizures. One complication is a board question.
Question #4. Envenomation is classically associated with?
A pancreatitis.
B. Encephalitis.
C. Diabetes.
D. Wound necrosis.
The answer is B pancreatitis. I’ve known the answer to this question since medical school. I didn’t know until this podcast that it’s not associated with American scorpions, but mainly those found in South America.
Centruroides scorpions are rarely fatal to adults. Symptoms typically last 6-30 hours, then resolve even without antivenom. Most deaths occur in children under two. Why? That’s question number 5.
A. Pediatric immune systems can't fight off the effects of the venom.
B. Delay in diagnosis
C. Venom dose
The answer is C. It's related to the relative dose. The sting delivers a certain amount of venom and you can imagine in a small child the relative dose compared to their size is much, much larger than in a full-size adult. Therefore, they suffer the effects much more acutely, especially under two years old. One study found grade 4 envenomation occurred in 16% of patients younger than 10 but only .7% of those above.
This same principle is true even with the death stalker scorpion, found in the Middle East and North Africa. It’s the scorpion with the most dangerous reputation worldwide, but the principles of treatment and symptoms are similar to Centruroides envenomation. It's more likely to be lethal in children. There is a very effective antivenom.
Interestingly scorpions can control the amount of venom they inject, called venom metering. When scared by a human, the scorpion can choose to inject half the amount of venom they would when attacking a prey. This may account for the fact that the vast majority, approximately 95% of envenomations, worldwide result only in local manifestations.
So back to your friend. She has systemic symptoms, Grade 4, and meets the criteria for antivenom. This hospital is in New York City and it doesn’t have any antivenom. What now? You call the poison center. Fortunately, they have Anascop and send it to you. The recommended dose is 3 vials in both children and adults, again related to the dose of venom, rather than the size of the patient.
What if the poison center didn’t have the antivenom? The treatment would be pain medicine, opioids and benzodiazepines for the muscle spasms. In addition to their other effects, sedation and anxiolysis, benzos are muscle relaxers.
United States poison centers get about 20,000 calls per year about scorpion exposures, most not surprisingly in Arizona. This is an extremely low number compared to other places. One study over a five-year period in Saudi Arabia found 72,000 reported exposures and you can imagine most are never reported. Worldwide it's estimated that there are 1.5 million exposures causing about 2 to 3,000 deaths. As with snakes, different antivenoms exist for different species.
Anascop, the Centruroides antivenom is an amazing antidote, it works quickly, binding to the venom and inactivating it. Most symptoms resolve within 1-2 hours. In the United States between 1930 and 1940, there were 40 deaths from scorpions mostly infants and children, but there's been only one death reported since 1970 and this was thought due to anaphylaxis rather than true envenomation thanks to modern medical care and antivenom.
Question 6. What drug of abuse has been confused clinically for scorpion envenomation in small children?
A. Methamphetamine.
B. Fentanyl.
C. Cocaine.
D. MDMA (ecstasy or molly)
Answer is A methamphetamine. I'm sorry to report that in the United States pediatric patients poisoned with methamphetamine have been confused for victims of scorpion envenomation. Both types of exposure cause tachycardia, high blood pressure, agitation and inconsolable crying. Both cause catecholamine, epi and norepi release and in the US, there's an overlap in geographical regions of scorpion habitats and human meth use.
Scorpions are cool, prehistoric animals, with evidence they existed at least 435 million years ago. It doesn't seem that they've changed much since. Ancient Egyptians believed they were created by decomposed corpses, crocodiles, and lizards. Interestingly, they’ve been used in warfare. Greeks defending a city from a besieging Roman emperor named Septimus Severus hurled bombs filled with scorpions down on the army, leading it’s to retreat. Even in more modern times, the Viet Cong placed scorpion traps in underground tunnels to envenomate American GIs.
As with, as far as I can tell, every other toxin known to man, scorpion venom has been used as medicine. In ancient China, it was used to treat seizures and spasms. It’s been used for malaria and arthritis. Even today, blue scorpion venom is touted as a treatment for cancer despite the fact it’s proven not to work, like many so many alternative cancer treatments. Not surprisingly, patients undergoing alternative treatments for cancer have a higher mortality rate than those taking traditional medicine and chemo.
There's a really cool development under investigation and showing promise for the medicinal use of venom. Chlorotoxin, also called BLZ – 100, is a peptide derived from scorpion venom being used to "paint” cancer cells. A cool fact about scorpions is that they are fluorescent under black lights. The molecule has been injected into humans to light up cancer cells during surgery so surgeons can see and remove them. It’s pretty cool, you can see 200 cells lit up with BLZ-100 versus an MRI which would require 500,000 cells to be able to see if there was a lesion. Pretty amazing, time will tell if it’s going to be an effective tool to treat cancer.
How do you obtain scorpion venom for research? This is an interesting topic in and of itself. The venom is considered one of the most valuable substances in the world reportedly worth $10 million per liter or $40 million per gallon. These numbers prompted a crazy speculation market a few years ago. People though raising and milking the scorpions, could yield a massive profit. Unfortunately, it didn't work out this way, resulting in money loss and bankruptcy.
Why? Researchers do use it in the lab and do pay a lot of money to purchase it. However, they usually only buy a few milligrams at a time. Not gallons. Additionally, it needs to come from a reputable source. Researchers say they are contacted by people who want to sell venom. But it's often unclear which species it’s from, the species are mixed together and the samples are unpurified. Meaning worthless for research purposes.
I love this quote from a Nathaniel Frank, owner of a lab in Wisconsin and a supplier of research grade venom. "If it was the most expensive liquid in the world, I'd be driving a Ferrari and not an old Ford truck.”
Back to your friend. An hour and half after receiving the antidote, she’s dramatically improved and requesting discharge. She asks what to do with the scorpion in her suitcase, a question you have no idea how to answer. This is a fictional case, as are all our cases, to protect the innocent. But it is based on real poisonings that have occurred periodically.
Last question in today’s podcast. A debate published in 1887 in the Lancet attempted to answer the following question. Do scorpions in a fire sting themselves to commit suicide?
A. True
B. False
Follow the Twitter and Instagram feeds both @pickpoison1 for the answer. Remember, never try anything on this podcast at home or anywhere else.
Thanks for listening. It helps if you subscribe, leave reviews and/or tell your friends. Transcripts are available at pickpoison.com.
While I’m a real doctor this podcast is fictional, meant for entertainment and educational purposes, not medical advice. If you have a medical problem, please see your primary care practitioner. Thank you. Until next time, take care and stay safe.