Stings and Bites: What To Do About Envenomation Injuries

The radio and pager alert your unit to a possible envenomation injury. The dispatcher tells you the caller was working in his garage, and, when he reached under his workbench for a tool, something bit him. Now, 10 minutes later, his right arm is swollen, and the swelling is slowly moving up toward his elbow.

Many questions should come to mind at this point. What bit him? You should generally know what poisonous creatures are in your area and begin forming ideas about the culprit. Was the creature poisonous? This is obvious from the dispatcher’s information, but what about specifics: How much venom? Was the injury a direct hit or a glancing bite or sting?

What treatment steps have the patient or bystanders taken? Some arcane but often used treatments are deleterious to the patient. Most important, does the creature pose a threat? Will you need to enter the house with a weapon, preferably one with a long handle? In a best-case scenario, someone will have captured the creature and will hand it to you as you walk in.

What Is An Envenomation Injury?

Envenomation, in the purest sense, is the introduction of poisonous venom into the body by means of a bite or sting. Envenomation can occur from a wide variety of creatures: large or small, aggressive or passive, cute and cuddly, or ugly and menacing. A large number of envenomation injuries occur from creatures that are barely noticed until an injury occurs, or from creatures that may appear quite harmless. The majority of envenomations occur from accidental or chance encounters. Rarely does a venomous creature attack or show unprovoked aggressive action. As Isaac Newton said, two objects cannot occupy the same space at the same time. When you inadvertently attempt to occupy the space held by another creature, it will usually defend itself.

In the United States, there are relatively few venomous creatures, compared with other parts of the world. For instance, Australia seems to be a particularly dangerous place to live, where venomous creatures on land and sea include: 61 species of snakes, 28 species of spiders and scorpions, 16 species of insects and 53 species of marine life. Even the benign duck-billed platypus has a venomous defense system.1 Other than for comparison, this article only covers the most common envenomation injuries by creatures indigenous to the United States. Because envenomation injuries comprise only a small number of emergency calls, only the most common creatures and injuries will be discussed, but emergency workers should become acquainted with creatures that live in their particular regions. Although many exotic venomous creatures reside in zoos and personal collections, most handlers are more prepared than emergency workers to manage those injuries.

General Treatment Protocols

Although a select few envenomation injuries require venom-specific hospital treatment, most injuries are treated the same way. Prehospital treatment consists of three objectives: 1) treating life-threatening symptoms; 2) treating other immediate symptoms; and 3) slowing the spread of venom. Additional treatments, such as antivenin administration or wound debridement, will take place at the hospital.

First and foremost is scene safety. The provider must make sure the venomous organism does not pose a threat to the patient or crew. If it does, take precautions to remove the threat. Depending on the creature, suitable precautions may range from summoning animal control to placing an insect between a boot and a hard place. Use common sense when ensuring scene safety. Reputably, half of all snakebites occur when people are trying to catch or harass the snake.2 Don’t become one of those people.

Once patient access is gained, assess and treat any life-threatening symptoms first. Follow the ABCs and consult your protocols for treating any respiratory or cardiac complications. Unless there has been a previous exposure, or the patient has an allergy, anaphylaxis is a rare complication of an envenomation. Even so, be aware of its possibility and treat accordingly. The stress of an injury can exacerbate pre-existing conditions like asthma or angina. Surfside Beach Rescue Squad in South Carolina recently treated a jellyfish sting that progressed into full-blown asthma and required IV epinephrine administration. Any serious envenomation injury will require ALS support.

Aside from life-threatening complications, any immediately presenting symptoms need to be addressed. Immediate symptoms can range from internal (nausea and vomiting, local or systemic aches and pains) to external (redness and swelling, trauma). Address these symptoms as they appear and consult your local protocols. Treatment of immediate symptoms will usually entail a small amount of bandage work and a large amount of supportive care and reassurance.

The third goal of envenomation treatment is to slow the spread of venom throughout the body. Modern prehospital treatment does not include orally sucking out the venom or using cut-and-suck devices to extract it. Although they are antiquated, you may encounter these treatments when you arrive on scene. If you do, educate the people about proper treatment, but don’t chastise or berate them. Remember to appear professional, even when the patients make it hard to do so.

Although any prehospital treatment that involves removing venom is controversial, one device used commonly by wilderness medical personnel is the Sawyer Extractor Pump, which is used to remove poisons delivered by snakes, insects and other stinging organisms without cutting the skin or causing further soft tissue trauma.3 Although Sawyer Products recommends the device for extracting snake venom, its use for snakebites has recently been questioned. Steve Grenard, a herpetologist and snake venom toxicologist at Staten Island University Hospital in New York, says its use is still valid for spider and insect bites, but no longer for snake bites. According to a recent study conducted at Loma Linda University Medical Center in California, “since snake venom is deposited deeper into the tissue, [the pump’s] use for removing snake venom is very limited.”4,5 Before using such a device, be sure your protocols allow it and that the situation calls for it. Venom-removal devices are not needed when a treatment facility is nearby. If your protocols allow the use of this device, make sure personnel have adequate training.

Primarily, patients need to remain calm, since a sympathetic nervous system response will cause their heart rate and muscle activity to increase, thus increasing absorption of the venom into the body. The former standard treatment of applying a compression bandage over the affected site is now quite controversial in the United States, although it is still considered standard treatment in Australia, where venomous snakes are abundant. The intent is to slow lymphatic blood flow and thus slow the spread of venom into the tissues and systemic circulation. On extremities, the band should be placed between the injury and the heart. On the torso or other areas, wrap the band as best you can manage, but be careful not to choke the patient or impede breathing. The band should be tight, but not tight enough to stop the circulation. It is recommended that it be like a tight watchband. If the injury is on an extremity, cover the entire extremity, but leave the tips of the fingers or toes exposed to allow assessment of distal circulation. The reason for controversy is that it is often difficult to assess the area once a bandage is applied, and it is difficult to keep it from becoming a tourniquet.6 If the situation dictates the need for a compression bandage, once the bandage is applied, immobilize the injured area with a splint, and strap the patient to the stretcher to prevent excessive movement. Do not make the patient walk to the ambulance.

A word of caution: Remember that the use of extraction devices and compression bandages is controversial and not allowed except in very remote situations. Be sure you do not overstep your treatment protocols when treating envenomation injuries.

General treatment of envenomation injuries is rather simple once the home remedies are pushed aside. Although proper treatment is simple to remember, it is also pertinent to review what EMS personnel should not do. Most of the “do not” items are commonsense, but, as you know, common sense is not always a ruling factor in patient treatment.

DO NOT:7-9

Apply ice, cold packs or freon spray to a wound.

Apply a tourniquet.

Apply electrical stimulation.

Incise the wound.

Apply alcohol.

Pour turpentine on the wound.

Attempt to orally remove the venom.

As soon as possible during or after treatment measures are taken, attempt to identify the creature from a description or visual sighting. Alert medical control to the identity of the offending creature. Many larger hospitals stock antivenins needed for creatures indigenous to their area. For creatures not normally found in the area, antivenin must be transported by air or ground ambulance to the patient, or the patient transported to the serum. For example, a small emergency department in the middle of Iowa is not likely to stock serum for an Australian King Brown snake, although a local or regional zoo may have it. Frequently, antivenins are transported to sites in the United States by Venom 1—the country’s only fire department-based antivenin bank, run by Miami-Dade Fire Rescue in Florida.10,11 Other repositories of antivenins would be poison centers or reptile centers. A book titled The Antivenom Index, published jointly by the American Zoo and Aquarium Association and the American Association of Poison Control Centers, gives detailed information on various antivenin treatment regimens and provides the U.S. locations for available antivenins.12

Once you notify the hospital about the creature in question, let them locate the treatment serums and arrange to have them brought to the hospital. Delivery of the patient to definitive medical care will never include transporting a patient to a zoo or reptile center.

If there are centers or handlers in your area that handle exotic venomous animals, it would be a good idea to visit them and be sure that they have a plan in place and/or their own stockpile of proper antivenin. While researching this article, I contacted a local company billed as the “Reptile Capital of the World.” When I asked about antivenin for cobras, mambas and the other venomous snakes on site, the animal handler responded that they did not keep antivenin on hand, and he did not know where to find treatment serum for any snakes other than at the hospital. Although it would seem commonsense to have on hand the antivenom for any venomous creatures in captivity, this may not always be the case, even though organizations like the American College of Medical Toxicology and the American Zoo and Aquarium Association recommend or require it.13–15 Preplanning in these situations will allow EMS personnel to be much more prepared than the people at risk for envenomation injuries.

Venomous Creatures Indigenous to North America

Venomous creatures found in North America generally fall into one of three categories: insects and arachnids, amphibians and reptiles, and marine creatures.

Insects and Arachnids

Hymenoptera (bees, hornets, wasps, ants). Toxin: Various toxins, depending on the organism.

Compared with other classes of venomous organisms, a large number of people die each year of insect stings. Wasps and bees alone are estimated to cause at least 30–120 deaths annually.16 Insects are the most common organisms from which anaphylaxis incidents occur. Most patients who experience severe allergic reactions to certain insects, or who have had prior problems, will understand the severity of a sting and be prepared with their own anaphylaxis kit. If the patient is unable to use a prescribed auto-injector, many state protocols now allow EMT-Basics and Intermediates to administer them. Always double-check prescription information and verify that the medication belongs to this person before administering.

Most stings result in minor localized symptoms and often will not require transport. An idiosyncratic or severe reaction to the venom can be treated with diphenhydramine at 25 mg IV or IM.

In the hymenoptera class, only the honeybee leaves a stinger. Stingers need to be removed before wrapping the injury. Remove the stinger by scraping horizontally across the skin with a credit card or other item to dislodge it. Be careful not to squeeze the venom sac at the top of the stinger, as it may still contain venom.

Black Widow Spider

Toxin: Neurotoxin

Black widow spiders—perhaps one of the most feared creatures in the United States—are found in all states except Alaska. The female of the species is known for its black body and hourglass shape on its back. The hourglass can be red, yellow or orange. Its venom is very potent. Severe symptoms include muscle spasms, severe pain near the bite site, seizures and paralysis.

Treatment is symptom-related. Severe symptoms will not usually manifest in the short time it will take to transport the victim. Any symptoms that do manifest should be treated as if they appeared with any other type of incident. Common symptoms can include inflammation, edema, severe pain and possibly seizures. A black widow spider bite can produce a serious amount of apprehension, so most of your treatment will be geared to calming the patient.

Brown Recluse Spider

Toxin: Hematotoxin, dermonecrotic toxin

The brown recluse is a small spider usually found only in the South and Midwest. It is recognizable by a brown body with a fiddle shape between its eyes. Bite sites usually become ischemic and necrotic after a few days, and tissue necrosis is likely to spread. The primary treatment is surgical excision of the necrotic tissue. There are usually no immediate symptoms other than redness and swelling at the bite site, so prehospital treatment is primarily supportive.

Identification of a brown recluse bite is key to proper hospital intervention, so do your best to get a description from the patient. Rapid treatment by a physician can often minimize the level of necrosis that develops after a bite.

Scorpion

Toxin: Neurotoxin, cardiotoxin

Forty species of scorpions are found in the South and Southwest. They are one of the most menacing creatures in this category and will become aggressive when threatened. Few scorpion stings are fatal, and only the Centruroides exilicauda, which is found in the southwestern United States, is considered especially dangerous. The symptoms of severe envenomation include nausea and vomiting, hypertension, tachycardia, restlessness, irritability, seizures and paralysis.17 Provide general envenomation and symptom-specific treatment. As with most other venomous insects and arachnids, the effects of scorpion stings are usually limited in scope and do not require much prehospital intervention.

Reptiles and Amphibians

Lizards

Gila Monster

Toxin: Neurotoxin

The gila monster is one of only two venomous lizards found on earth.18 Although its appearance is striking and it would appear quite dangerous, its bite is rarely fatal to humans. The gila monster is found in the southwestern United States.

Gila monsters have a series of small teeth and inject their venom by chewing on their victim and allowing the venom to flow into the bite wounds. They are tenacious in hanging onto a victim and are known to roll over and over in order to subdue their prey. As such, the most likely treatable injury from a gila monster bite will be soft tissue injuries to the bite site. Most often, the gila monster will have to be pried off the victim. As an example of their tenacity, once they bite, researchers have reported gila monsters clinging to hard metal objects like car door handles for up to 15 minutes.19 The most common symptoms are synonymous with those of any biting animal: pain, edema and bleeding. Occasionally, the venom will cause nausea and/or vomiting. Specific treatment for the poisons injected into the patient is usually not necessary.

Snakes

Pit Viper

Toxin: Hematotoxin

Coral Snake

Toxin: Neurotoxin

As with most other venomous creatures, few fatalities occur with snakebites. Two families of poisonous snakes are found in the United States: pit vipers and coral snakes. Pit vipers include rattlesnakes, water moccasins and copperheads. They’re characterized by a triangular head and pits located behind their eyes. Pit vipers have large fangs attached to venom sacs. Coral snakes, on the other hand, have a series of small teeth. Their pattern of body markings is quite unique and consists of red, yellow and black stripes that run horizontally across their body.

Identifying snakes is sometimes difficult, as some nonpoisonous snakes look similar to the poisonous ones in order to fool predators. Don’t endanger yourself in order to identify a snake. Certainly don’t bring a live or dead snake to the hospital.20 Snakes that appear dead may not be; even dead snakes can envenomate a person through their fangs.21 If you can’t readily identify the snake, just treat and transport. Although many people swear by it, an old children’s nursery rhyme is not a reliable tool for identifying coral snakes: “If red and black’s a friend of Jack, red and yellow will kill a fellow.”

A severe pit viper bite can kill rapidly, but most deaths occur within 6–30 hours.22 Severe symptoms include nausea and vomiting, weakness, tachycardia, hypotension, numbness and tingling around the face and head, and respiratory collapse.23 Symptoms of coral snake bites differ. They include ataxia, slurred speech, hypersalivation, paralysis, seizures and respiratory failure.24

Initiate general envenomation treatment measures for an injury by either type of snake and transport immediately.

Marine Animal Injuries

Stonefish

Toxin: Myotoxin

Jellyfish

Toxin: Cardiotoxin, hematotoxin, dermonecrotic toxin

Stingray

Toxin: Cardiotoxin

Other toxins vary according to the organism.

Marine animal envenomations occur from a wide variety of creatures: fish, skates and rays, jellyfish and starfish, among others. A complete list of marine venom-producing organisms would require more space than this article permits. Venomous creatures live in both fresh and saltwater at all temperature ranges; therefore, a marine injury can occur virtually anywhere.

All known venomous marine creatures produce a heat-sensitive venom. The proteins that make up the venom are sensitive to both high and low temperatures.25–27 Because of this, applying a hotpack to the injury site during transport often deactivates much of the venom and produces immediate pain relief for the patient.28

Another characteristic of marine envenomations is that they often produce a pain response that is disproportionate to the clinical signs of the injury. This is primarily because the stinging systems of many marine animals leave behind the stinger, pieces of the stinger shaft, or spines that remain in the wound. Complete debridement at the hospital will be needed to treat the pain and possible infection caused by these foreign bodies.29 Rely on heat, immobilization and noninvasive pain management techniques, such as distracting the patient or music therapy.

Stingrays and many fish leave the stingers embedded in the injury site. If possible, remove the stinger. Because of the presence of bacteria and pollutants in the water, any debris left in the wound can cause severe infections. Stingrays also leave behind other material like the stinger shaft, which will need to be removed as well. Sea urchin spines often break off in the wound and must be removed at the hospital. Any deep injury or stinger that is difficult to remove should be left in place and treated at the hospital. Surgical debridement may be required to completely treat the patient.

Jellyfish possess minutely small stinging cells called nematocysts, which can be attached to the jellyfish or free-floating in the water. Venom is injected or fired when the cells come into contact with human flesh. To provide pain relief and immediate treatment for a jellyfish sting, any remaining nematocysts must be neutralized and removed from the skin.

There are several home remedies that are considered cures for jellyfish stings, but scientific evidence for them is lacking. Do not allow a patient to urinate on the sting site. Some believe that the ammonia in urine will neutralize the sting. It may work, but, for the sake of hygiene and public decency, it shouldn’t be done. The proper method for neutralizing nematocysts and stopping them from firing is to pour household vinegar on the wound.30 Then, scrape the area with a credit card or other item. Do not brush off the area with an ungloved hand, as the cells can attach to your hand and possibly still fire. After removing the stinging cells, transport the patient to the hospital for further assessment.

Most jellyfish stings are minor, but are extremely painful. The Portuguese man-of-war is an exception. The man-of-war is found on the Atlantic and Gulf Coasts and is capable of producing severe envenomation injuries, due to the sheer number of nematocysts on its tentacles. Jellyfish in other parts of the world, like the box jellyfish of Australia, are extremely dangerous and are becoming more and more common in U.S. waters.

Summary

Although serious envenomation injuries are rare in the United States, all emergency workers should be prepared for them. Most severe complications occur in people with previous allergies or pre-existing conditions. Many people, especially those with prediagnosed allergies, will be capable of self-treatment prior to EMS’s arrival; however, prepare for the worst. EMS personnel should know how to treat virtually any envenomation injuries with general practices, and should inform the receiving hospital so venom-specific treatment can be prepared. Crews should also know what creatures are indigenous to their areas and know what to expect when the tones go off.

Be aware that a side effect of any animal bite or sting, whether venomous or not, is bacterial infection.31 Remind patients of this. The hospital physician will also educate them about infection. If you respond to a call, but the patient refuses transport and signs a waiver, you must educate him about possible bacterial contamination from the bite or sting. Never waive a patient until he has been educated regarding his injury and still refuses transport.

References

1. www.usyd.edu.au/anaes/venom/envenomation.html.
2. https://gorp.away.com/gorp/health/snakefaq.htm.
3. Sawyer Products, 2003. www.sawyerproducts.com/Extractor/extractoruse.htm.
4. Grenard Steve. Telephone interview, 17 September 2003.
5. Bush SP, Hegewald KG, Green SM, et al. Effects of a negative pressure venom extraction device (extractor) on local tissue injury after artificial rattlesnake envenomation in a porcine model. Wilderness Environ Med 11(3):149–151, Fall 2000.
6. McKinney PE. Out-of-hospital and interhospital management of crotaline snakebite. Ann Emerg Med 38(5):607–608, Nov 2001.
7. Henkel J. For goodness snakes! Treating and preventing venomous bites. FDA Consumer. U.S. Food and Drug Administration, November 2002.
8. Campbell JA, Lamar WW. Venomous Reptiles of Latin America. Ithaca, NY: Cornell University Press, 1989.
9. Mara WP. Venomous Snakes of the World. Neptune City, NJ: TFH Publications, Inc., 1995.
10. de Gale A. “Rescue team has handle on treating snakebites.” The Herald 16 July 2001: B1.
11. Garlock M. “Miami-Dade Fire Rescue: Venom one becomes full-time unit.” Firehouse, p. 40, Nov. 2003.
12. Boyer DM, ed. Antivenom Index. San Diego: The American Zoo and Aquarium Association and The American Association of Poison Control Centers, 1999.
13. American College of Medical Toxicology. Position Statement: Institutions Housing Venomous Animals, 2002.
14. American Zoo and Aquarium Association. Guide to Certification of Related Facilities, 2004.
15. Zoo keeps antivenin for snakebites. Sun News 3 Feb. 2004: C3.
16. www.emedicine.com/emerg/topic55.htm
17. Reeves J. Clinical Toxicity Review 20(6): Mar 1998. Massachusetts Poison Control System.
18. Ernst C. Venomous Reptiles of North America. Washington DC: Smithsonian Institution Press, 1992.
19. Bogert CM, Del Campo RM. Gila monster and its allies. Bull Amer Mus Natur Hist. 109:1–238, 1956.
20. Ernst C. Venomous Reptiles of North America. Washington DC: Smithsonian Institution Press, 1992.
21. Kitchens CS, Hunter S, Van Mierop LHS. Severe myonecrosis in a fatal case of envenomation by the canebrake rattlesnake. Toxincon 25:455–458, 1983.
22. Ernst C. Venomous Reptiles of North America. Washington DC: Smithsonian Institution Press, 1992.
23. Ibid.
24. Ibid.
25. Meier J, White J, eds. Handbook of Clinical Toxicology of Animal Venoms and Poisons. New York: CRC Press, 2003.
26. Russell FE, Fairchield MD, Michaelson J. Some properties of the venom of the stingray. Med Arts Sci. 12:78, 1958.
27. www.usyd.edu.au/anaes/venom/marine_enven.html.
28. Auerbach P. Stinging truths, part 1. Dive Training, p. 75, May 1995.
29. Meier J, White J, eds. Handbook of Clinical Toxicology of Animal Venoms and Poisons. New York: CRC Press, 2003.
30. Edmonds C, Lowry C, Pennefeather J. Diving and Subaquatic Medicine. Woburn, MA: Butterworth-Heinemann, 1992.
31. Ernst C. Venomous Reptiles of North America. Washington DC: Smithsonian Institution Press, 1992.