Snake bites
"There are approximately 3000 species of snakes worldwide, of which 600 are venomous. According to data released by the WHO, 421,000 to 2.5 million patients are bitten by venomous snakes, of whom 20,000 to 100,000 die each year. In the United States (US) and Canada, around 6,500 people suffer from snakebites annually, resulting in 5-6 deaths."
The most common venomous snakes in the DFW area are (From Venomous Snakes of the Dallas/Fort Worth Metroplex – DFW Urban Wildlife):
Southern Copperhead
Broad-banded Copperhead
20" - 37", warning bite (dry bite)
Western Cottonmouth (Water Moccasins)
27" - 62", opens its mouth widely when startled, triangle shaped head larger than body
24" to 48", Black/yellow/red rings
14" - 36"
Up to 59"
Western Pigmy Rattlesnake
Western Diamondback Rattlesnake (most dangerous)
Field Management: What Do You Do?
From: How to survive a snakebite in the wilderness — The Asclepius Snakebite Foundation and Snake Bite Management: A Scoping Review of the Literature
"When in the field, accurate assessment of the wound is difficult, as there are no immediate differentiating symptoms between a snake bite with or without envenomation."
"With the exception of the Texas Coral Snake all of these snakes share very similar venom. The venom of the Texas Coral Snake is the most potent of any snake in North America, and bites from this snake are considered very serious. Heavy does of anti-venom and artificial respiration are often required to successfully treat a coral snakebite."
After sustaining a snake bite, move out of the snake’s striking distance (1/2 to 2/3 of the snake's total length) and sit down. Blood pressure likely will decrease so sit before you drop. Take a picture of the snake, if you or preferably someone else can do it safely. Do not put yourself or someone else in danger to get a picture.
Call 9-1-1. Tell them your location, you were bitten by a snake, the time you were bitten and your symptoms. Never hang up on a 9-1-1 call.
Remove any rings, bracelets/anklets, straps or anything that can become tight around your arms or legs. Your body will likely swell so better to get these off quickly.
Use a sharpie (one of the most valuable components of a first aid kit) to circle the bite area, write down the time, and write down any symptoms in the order they occur. Common symptoms are pain, swelling, hives, difficulty breathing, weakness, numbness
Monitor your breathing and circulation as these vital functions can deteriorate within minutes.
Current recommendations for field treatment include limiting the victim’s activity while lying them flat and keeping the bitten extremity immobilized at heart level. You do not have to "immobilize" the area with a splint, just don't keep moving it around. If you do immobilize, don't wrap the area tightly.
However, if no help will arrive for hours, do your very best and get up and walk to where you can get help!
Common misconceptions about snake bite management abound.
The use of a tourniquet, thought to reduce the return of venom to the central circulation, actually restricts essential blood flow to the affected tissue, increasing local edema and potentiating the venom’s local effects. Wound compression, which involves wrapping the affected extremity distal to proximal at an optimal pressure of 55 mm Hg, has been shown to be error prone and is not recommended.
Cut and suck: Initial treatment of wound incision and suction or suction alone was thought to withdraw a portion of the venom load, thus limiting the quantity of absorbed venom; however, studies have shown it can actually worsen patient outcomes and is therefore no longer recommended.
Do not use ice! Ice vasoconstricts meaning it makes the blood vessels smaller. Yes, intuitively you'd think this prevents the spread of the venom, but can dramatically increase tissue damage.
Drugs like ibuprofen and aspirin interfere with normal clotting of the blood and this may lead to increased internal bleeding.
Application of medicinal herbs, chemicals, and intense scrubbing/cleaning of the wound is also not recommended.
Medical professionals may find Clinical Algorithms — The Asclepius Snakebite Foundation, Snakebite Envenoming Diagnosis and Diagnostics useful.
Antivenom Risks: "In our observations, the most common clinical manifestation of IRR [Infusion Related Reactions] was a diffuse cutaneous rash, present in 82% of cases, followed by respiratory manifestation in 46% and facial swelling in 23%." "In general, our results suggest that although frequent, infusion reactions related to antivenom sera are, in most cases, of mild to moderate intensity, with characteristics compatible with type I hypersensitivity reactions. The rate of serious infusion reactions was 9%, affecting respiratory and haemodynamic stability, but this rate was completely reversed with specific treatment. Only one patient developed symptoms compatible with serum sickness. The occurrence of life-threatening respiratory manifestations warns of the need to equip the healthcare units responsible for antivenom serum administration with the minimum necessary infrastructure and periodic training of health professionals."
More Information:
"Envenomation is the result of the injection of a highly specialized toxic secretion, called venom, by a venomous snake into a human, usually in accidental situations. Venom is injected through the snake’s fangs, which are teeth connected via a duct to a venom gland. The composition of snake venom shows high complexity and diversity, resulting in variable biochemical and toxicological profiles that determine a wide range of clinical manifestations.
Currently, the only accepted treatment for snakebite envenomation involves intravenous administration of conventional antivenoms comprising antibodies or antibody fragments derived from the plasma of large mammals (generally horses, but also sheep, goats, or rabbits) that have been previously immunized with non-lethal venomous doses.
According to the Centers for Disease Control and Prevention (CDC), an estimated 7000 to 8000 snakebites occur annually in the United States (CDC 2018). The 2017 annual report of the American Association of Poison Control Centers (AAPCC) showed around 7000 snakebites. Copperheads (2035), Crotalids, (1028), and rattlesnakes (753) were reported as the predominant species involved in envenomation; however, death is a rare outcome and only 5–10 deaths were reported."
"There are 5000-10,000 snake envenomations (snake bites where the venom is injected vs a dry bite where no venom in injected by the bite) annually in the United States. Fortunately, few are fatal. We identified 101 fatal bites from native snakes. Rattlesnakes accounted for 74 (90.2%) of the 82 deaths for which the species was known or which occurred where rattlesnakes are the only native crotalids. There were five fatalities attributed to copperheads, two due to cottonmouths, and one caused by an eastern coral snake. Males were disproportionately affected. The median age for victims was 40 years old."
From the 2021 paper entitled, Snake Bite Management: A Scoping Review of the Literature
Common symptomatology can be identified across snake species.
Presenting symptoms of any envenomation (injection of venom via the snake bite) can include generalized weakness, numbness, paresthesia, and pain.
A snake’s venom is composed of a variety of enzymes and proteins that are responsible for both local tissue damage and systemic manifestations. Each species has altering levels of gene expression that control which proteins and enzymes are expressed. For example, certain species’ venom primarily expresses metalloproteinases, which can lyse (destroy) membranes and cellular adhesions, causing rubor (redness), calor (heat), tumor, and tissue necrosis (death).
This can present clinically as tachycardia (fast heartbeat), petechia (small red/purple spots on the skin), confusion, vomiting, disseminated intravascular coagulation (small blood clots throughout the body), acute renal failure, shock, and compartment syndrome.
Commonly, laboratory values show depleted fibrin levels, anemia (intravascular hemolysis), thrombocytopenia, and elevated BUN, creatinine, and prothrombin time/partial thromboplastin time
Alternatively, gene expression of either alpha protein or phospholipase A2 can give the venom a neurotoxic effect in which presynaptic or postsynaptic blockade prevents signal transmission. This can lead to visual disturbance like ptosis - drooping upper eyelid) and diplopia (double vision), dysphagia (difficulty swallowing), diaphoresis (profuse sweating), peripheral nerve palsy (damage to the nerves in your limbs and organs), diminished reflexes, and in severe cases, respiratory depression, and paralysis.