- Venomous & Nonvenomous Snakebites
- Symptoms & Signs
What is a venomous (poisonous) snakebite?
A venomous (poisonous) snake bite is a bite or a puncture wound made by a snake that is capable of injecting, secreting, or spitting venom into the penetrated skin wound, mucus membranes or the eyes where the toxin can be absorbed. Worldwide, there are about 20,000 to 100,000 snakebite deaths per year. In North America, there are about 25 species of snakes able to secrete venom. However, non-native poisonous species are present in zoos and held in private homes or other areas by snake collectors. Consequently, almost any type of venomous snake bite can be encountered in the US. About 7,000 snake bites are reported in the US per year, but because snake bites are not required to be reported, it is estimated that up to 45,000 bites per year may occur with about 8,000 by poisonous snakes. About five deaths per year are reported due to snakebites. The most common venomous snakes in the US are:
- Cottonmouths/water moccasins
- Coral snakes
The first three are pit vipers (have a pit used to detect temperature changes and two movable fangs), and the coral snake is an elapid with short fixed fangs and no pit. Brown snakes are also elapid and are very poisonous.
What is a nonvenomous (nonpoisonous) snakebite?
- A nonvenomous (nonpoisonous) snake bite is a bite or puncture wound made by a snake that is incapable of secreting venom. This should be distinguished from a dry bite.
- A dry bite is a bite by a venomous snake that does not inject any venom.
- Even bites that are from a nonvenomous snake or are dry need to be evaluated as they can lead to significant tissue damage or infections.
What are the symptoms and signs of a venomous snakebite?
The symptoms of a venomous snakebite depend on the type of toxin(s) secreted into the bite or puncture wound, and in part, on how much toxin is present in the tissue. The types of symptoms produced can be grouped into four groups:
- Cardiotoxins act on heart tissue.
- Neurotoxins act on nervous system tissue.
- Cytotoxins act on tissue at the site of the bite or on tissue that directly absorbs the venom.
- Hemotoxins act on the blood coagulation system and may cause internal bleeding.
Some toxins may cause more than one of these effects. Because of the various symptoms that can occur with venomous snakebites, the potential signs and symptoms to look for, as listed by the CDC include the following:
- A pair of puncture marks at the wound
- Redness and swelling around the bite
- Severe pain at the site of the bite
- Nausea and vomiting
- Labored breathing (in extreme cases, breathing may stop altogether)
- Disturbed vision
- Increased salivation and sweating
- Numbness or tingling around the face and/or limbs
Symptoms from these toxins are somewhat variable and may occur quickly within minutes or they may be delayed for hours, depending on the toxin type and the amount absorbed. In general, small children are more vulnerable to snake bites because the relative larger amount of toxin absorbed in relation to their smaller body size can make the toxin effect more potent. Individuals with medical conditions like heart disease or other chronic diseases are also at higher risk of complications due to snakebite. The quick action of many toxins usually does not allow the immune system a chance to counter the toxin’s effects.
Identification of the snake helps emergency health care professionals to both anticipate the potential symptoms, and it allows for more rapid and appropriate treatment of the venomous snake bite. A detailed description and a picture of the snake will help identify the type of snake and the type of toxin. Do not waste time, however, in transporting the patient to an appropriate medical facility and do not put others in jeopardy of getting bitten.
The World Health Organization (WHO) has listed snakebite to its list of neglected tropical diseases. Sub-Saharan Africa has a lack of antivenom supplies; minute-to-minute delays in treatment can affect outcomes; for example in April 2019, a woman died on her wedding day a few hours after a snakebite in Nigeria.
How do medical professionals diagnose a venomous snakebite?
Any snakebite needs emergency medicine and evaluation. Identification of fang or bite marks is done, even if the snake is nonvenomous, to determine local trauma or tissue damage at the site of the bite. Identification of the snake type by description or picture, along with the circumstances of the bite and the surrounding environment usually provides the health care professional a working diagnosis. For example, a snakebite occurring in dry west Texas is likely a rattlesnake bite, while a snakebite in a swampy area of the U.S. is likely a water moccasin, and Tiger snakes (body has bands of colors) are found mainly in Australia and its costal islands. A zookeeper or private snake owner/collector who is bitten will likely know the exact type of snake that caused the bite or toxic spray (spitting cobras).
What is the treatment for a venomous snakebite?
After a snake bites, there are two phases of treatment.
- The emergency treatment is provided on-site and during transport to an appropriate health care facility.
- The health care facility stabilizes the patient, administers antivenin if deemed necessary, and provides supportive treatment.
Phase one of snakebite treatment
Many past home remedies, snakebite kits and other first aid treatment methods have been shown to make the effects of the snakebite worse. Consequently, the CDC has issued guidelines to use after the threat of additional bites to the patient or others is eliminated, about what to DO and what NOT TO DO if a snakebite occurs. The following are CDC recommendations:
- Seek medical attention as soon as possible (dial 911 or call local Emergency Medical Services)
- Try to remember the color and shape of the snake, which can help with identification and treatment of snake venom in the snakebite.
- Keep still and calm. This can slow down the spread of venom.
- Inform your supervisor (if the bite occurs at work).
- Apply first aid if you cannot get to the hospital right away.
- Lay or sit down with the bite below the level of the heart.
- Wash the bite with soap and water.
- Cover the bite with a clean, dry dressing.
Do NOT do any of the following:
- Do not pick up the snake or try to trap it.
- Do not wait for symptoms to appear if bitten, rather seek immediate medical attention.
- Do not apply a tourniquet.
- Do not slash the wound with a knife.
- Do not suck out the venom.
- Do not apply ice or immerse the wound in water.
- Do not drink alcohol as a painkiller.
- Do not drink caffeinated beverages.
Not included in the CDC recommendation is the bite of the Australian elapid snake, also termed a sea snake, which is emergently treated with a pressure bandage at the bite site with splinting and extremity immobilization. Others suggest no use of electric shocks for any snakebite.
Phase two of snakebite treatment
The second phase of treatment consists of stabilization and supportive care, and when medically indicated, administration of antitoxin (antivenin) specific for the snake species and a tetanus booster vaccine. A good practice is to call your local poison control center or the national Poison Help Line (1-800-222-1222), and also to consult a toxicologist and a surgeon to help care for the patient. Certain patients may require surgical treatment and admission to the hospital, as some snakebites can be life-threatening.
The treatment of non-venomous snake bites includes local wound care at the site of the bite, removing snake teeth if left in the bite site, attending to any trauma at the bite site, and a tetanus booster if needed. Some wounds may become infected and require additional treatment with antibiotics.
What are the complications of a venomous snakebite?
The complications of venomous snake bites can range from mild to severe and may mimic other human diseases like hemorrhagic fever, ALS (Amyotrophic Lateral Sclerosis) and autoimmune disease, for example. Complications include pain and swelling at the bite site, allergic reaction, vision damage (from toxin sprays especially), compartment syndrome (localized severe swelling that can damage or destroy nerves and blood vessels, leading to muscle necrosis), infection (including methicillin-resistant bacteria), limb loss, gangrene, sepsis, internal bleeding, cardiac damage, respiratory compromise, possible long-term psychological effects or mental disorders, and even death.
Is it possible to prevent a snakebite?
Many snake bites can be prevented as most snakes are not aggressive toward humans unless they sense danger. Consequently, avoidance of snakes usually prevents a bite, so people should not try to handle, capture or threaten (for example, tease with a stick) any snake. Statistical studies suggest that about 40% of all snake bites in the US occur in people that consumed alcoholic drinks. If a person's workplace involves areas known to be a habitat of snakes, wearing protective boots, thick pants, and gloves may reduce the chances of a snake bite; or at least it may reduce the bite trauma and the amount of venom distributed.
What is the prognosis for a venomous snakebite?
Most snakebites, when quickly and appropriately treated, have a good prognosis. If left untreated for various increasing lengths of time after the snake bites, the prognosis usually diminishes while the complications increase. Deaths are unlikely, as fewer than 10 deaths per year are due to snakebites in the U.S.
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United States. Centers for Disease Control and Prevention. "How to Prevent or Respond to a Snake Bite." CDC.gov. Sept. 21, 2018.
United States. Centers for Disease Control and Prevention. The National Institute for Occupational Safety and Health (NIOSH). "Venomous Snakes." May 31, 2018.
White, Julian, et al. "Snakebites worldwide: Management." UpToDate.com. Jan. 30, 2019.