Although most people are afraid of snakes, the vast majority of the 3,000 species in the world are harmless to humans. Only about 300 merit the label, “venomous”.
The tropical waters of the Pacific and Indian Oceans are home to at least 52 species of sea snakes, and all of them are venomous. Interestingly, there are no sea snakes in the Atlantic Ocean, Mediterranean or Caribbean. Sea snakes are usually not aggressive. Although they are highly venomous, only some bites result in significant symptoms or envenomation. The fangs of most sea snakes are not long enough to penetrate even a thin wetsuit. Bites typically occur when fishermen remove the snakes from fishing nets, or if the snake is stepped on while wading.
World Distribution of Snakes. Source: Wikipedia
Every year, between one and two million people worldwide are bitten by snakes, including by non-venomous species. According to the World Health Organization, 30,000 to 40,000 people die each year from snakebite. Other sources claim that the annual number may reach 100,000 deaths.
The diagram below shows the distribution of snakebites per year throughout the world.
If you’re exploring on land or sea, it’s wise to have some knowledge of dangerous indigenous species. If, for example, you are hiking in New Zealand or Ireland, don’t worry: Snakes do not live in either country.
It’s different, however, if you’re in the Australian Outback: Twenty-one out of the 25 most venomous snakes in the world live here. Not only does Down Under have the most toxic land snakes, but also some of the deadliest sea snakes. Surprisingly, Australia only averages three or four snakebite deaths every year and has recorded just one death from a sea snake in the last 80 years. Sea snakes may be deadly but they’re also mellow, and you have to go out of your way to get one to bite you.
To put Australia’s dangerous reptiles in perspective, many of us go our entire lives without ever meeting a snake, and 99 percent of us run into them less than a handful of times. Despite many hours hiking in bushland, and playing golf and traveling all over the country, I have seen snakes only twice in the last 20 years. The first was a Western Brown on a remote road in Western Australia; the second was an Eastern Brown on a golf course on the east coast. Both times, the snake simply slithered away.
Most snakebite victims live in Asia, which is less known for its venomous snakes. The country with the most annual snakebite deaths is tiny Sri Lanka.
| Region | Low Estimate | High Estimate |
|---|---|---|
| Asia | 15,385 | 57,636 |
| Australasia | 2 | 4 |
| Caribbean | 107 | 1,161 |
| Europe | 48 | 128 |
| Latin America | 540 | 2,298 |
| North Africa / Middle East | 43 | 78 |
| North America | 5 | 7 |
| Oceania | 227 | 516 |
| Sub-Saharan Africa | 3,529 | 32,117 |
| Total: | 19,886 | 93,945 |
Source: Wikipedia
Snake venom is merely modified saliva. It combines many different proteins and enzymes. There are four types of snake venom:
Myotoxins Small, basic peptides that lead to severe muscle death by restricting blood supply. These peptides act very quickly, causing instantaneous paralysis to prevent prey from escaping. The victim eventually dies from an inability to breathe.
Cardiotoxins Attack the muscles around the heart, leading to heart failure.
Haemotoxins Kill red blood cells, disrupt clotting, and/or cause organ degeneration and general tissue damage. Some venoms reduce the level of clotting (coagulation) of blood and have been chemically developed into anticoagulation drugs. Other haemotoxins trigger rapid clotting, causing blood vessels to become blocked.
Neurotoxins Destroy nerve tissue and can have immediate or long-lasting impact by causing neurons to malfunction or by disrupting inter-neuron communication. Certain neurotoxins are so potent that they have been developed into chemical weapons, such as the nerve agent Sarin, which can kill a person within 10 minutes.
No snake venom contains just one type of toxin –- most snake venom is a cocktail. This variable combination makes reactions to snakebite vary from species to species.
The most venomous snakes in each continent are:
North America
Over 20 species of venomous snake live in North America. Every state except Alaska has at least one, but they only live in 4 of 10 provinces in cooler Canada. The five most dangerous snakes in North America, in no particular order, are:
Cottonmouth
Also known as the water moccasin, it is the only semi-aquatic viper in the world. A strong swimmer, it lives in the southeastern United States, including remote islands in the Gulf of Mexico.
Cottonmouth. Photo: Pest Wiki
Its powerful cytotoxic venom is so destructive that it can eat away flesh and lead to grisly amputations. Their preference for hiding in water and attacking when least expected means that bites are also relatively frequent.
Timber rattlesnake
Timber rattlesnakes are large, with long fangs and potent venom, which they can pump into their prey in alarming amounts. Thankfully, their mild temperament and characteristic warning rattle means that very few fatalities occur. This patient snake often gives lengthy warnings before attacking.
Black diamond rattlesnake
This dangerous rattler boasts no fewer than seven different subspecies, some of which have a highly toxic venom that attacks nerve endings, requiring a much higher dose of antivenom to treat. They roam widely across the western half of North America, from British Columbia to northern Mexico.
Tiger rattlesnake
The tiger rattlesnake has the smallest head of any rattlesnake, but this pit viper has an incredibly potent venom and is considered the most dangerous snake in the Western Hemisphere.
Tiger Rattlesnake. Photo: californiaherps.com
The tiger lives only in a small area near the Arizona-Mexico border, and few bites have been documented. The small amount of venom it injects per bite also limits fatalities.
Copperhead
The copperhead is perhaps responsible for the most bites of any snake on this list. The snake isn’t inherently more aggressive but tends to “freeze” when approached and will bite when accidentally stepped on.
The copperhead also has what is believed to be the weakest venom of all pit vipers.
Also in the top 10 are the Eastern coral snake, western diamondback, eastern diamondback, prairie rattlesnake and Mojave rattlesnake.
Europe
Europe does not have the range or potency of the venomous snakes of other continents, but a number of species can still cause human deaths. The top five are:
Nose-horned viper
Occurs in southeastern Europe, from Hungary and Austria to Italy, Romania, former Yugoslavia and northern Albania.
Nose-Horned Viper. Photo: ultimate exotics.co.za
Asp viper
Found in southwestern Europe: northeastern Spain, Andorra, most of France, Monaco, Italy, San Marino, Switzerland, Slovenia and southwestern Germany.
Turkish viper
Not surprisingly, found in Turkey.
European viper or adder
From western Britain to the Russian Pacific. Known in antiquity as the asp, it was thought to be the snake that Shakespeare had Cleopatra embrace after the death of her beloved Mark Anthony. Others assert that the literary culprit was a horned viper. Ruining a good story of suicide-by-asp, modern scholarship suggests that she drank poison.
Lataste’s viper or snub-nosed viper
Found mainly on the Iberian Peninsula and northwestern Africa.
Africa
The African continent is home to many different snake species, some of which are among the world’s most dangerous, including:
Black Mamba
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The black mamba is not the most venomous African snake, but is the most feared because of its size and aggressiveness. With an average length of 2.5m, black mambas are the fastest of all indigenous African snakes, and often strike more than once. Their venom, powered by both neurotoxins and cardiotoxins, can cause a human to collapse after just 45 minutes. Without antivenom, death is almost certain, usually within 7 to 15 hours.
Puff Adder
Considered to be Africa’s deadliest snake because it is responsible for the most human fatalities. It ranges throughout sub-Saharan Africa and relies on its exceptional camouflage for protection. It freezes rather than flees from potential danger. As we’ve seen with other species, this increases the danger, because it is easy to step on.
Boomslang
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Restricted to sub-Saharan Africa, the boomslang is one of the most venomous snakes on the continent. Its haemotoxic venom disables the body’s natural blood-clotting and triggers uncontrollable external and internal bleeding. Boomslangs are typically timid, though, and flee rather than attack.
Gaboon Viper
The Gaboon viper holds several records: Its giant five-centimetre fangs are the longest of any venomous snake. Through them, it also injects the most venom, and is the heaviest snake in the viper family. It lives in forests throughout West, Central and parts of East Africa and is largely nocturnal.
Egyptian Cobra
The Egyptian cobra occurs throughout most of North Africa above the Sahara, and in parts of West and East Africa. Glands behind its eyes produce a deadly neurotoxin that affects the nervous system, ultimately causing death from respiratory failure. (The chest muscles and diaphragm are paralyzed, and the victim can’t breathe.) Egyptian cobras are typically docile unless threatened, in which case they will assume an upright posture and spread their characteristic cobra hood as a warning before striking.
Rounding out the top 10 are the West African carpet viper, Cape Cobra, eastern green mamba, Mozambique spitting cobra and Rinkhals.
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Mozambique spitting cobra. Watch your eyes.
Asia
The most dangerous snakes in Asia are:
King Cobra
This highly intelligent snake from Thailand, southern China, the Malaysia Peninsula and the Philippines can reach up to 5.5 metres long, making it the largest venomous snake in the world. While its neurotoxic venom is not the most potent, the amount of venom it releases is enough to kill an elephant.
King Cobra. Photo: natgeotv.com
Common Cobra or Asiatic Cobra
A very common species found throughout Asia, it is responsible for many deaths annually, partly because it lives around farms, fields and even inside houses, where it searches for rodents. The cobra readily bites when aroused or threatened. Its venom is highly neurotoxic, causing respiratory paralysis and tissue damage.
Egyptian Cobra
This extremely dangerous snake also turns up in Iraq, Syria and Saudi Arabia.
Once aroused, it will attack and continue striking until it feels it can escape. Its neurotoxic venom — much stronger than the Common Cobra’s — causes paralysis and death from respiratory failure.
Green Tree Pit Viper
This small arboreal snake lives in India, Burma, Malaysia, Thailand, Laos, Cambodia, Vietnam, China and Taiwan. Though not considered a deadly species, it remains dangerous especially because most of its bites occur in the head, shoulder and neck, as it strikes from low overhanging branches.
Habu Pit Viper
This Japanese snake often hides in old houses and rock walls. It is quite aggressive, has bitten many people, and its bite is potentially lethal. Its haemotoxic venom causes pain and considerable tissue damage.
Saw-scaled viper. Photo: she-india.org
A special mention goes to the small Saw-scaled viper of Syria, Israel, Jordan, Lebanon, Iraq, Iran, Saudi Arabia, Pakistan and Sri Lanka. This ill-tempered snake will attack any intruder and is responsible for more human deaths in Asia than all the other venomous snakes combined. Its highly haemotoxic venom is said to be five times more toxic than that of cobras.
Central and South America
Fer-de-Lance
Its long fangs can deliver a large cocktail of various toxins. Very fast and easily irritated, it rises up if threatened. Affected limbs often require amputation if not treated.
Fer de Lance. Photo: epicadventurescr.com
Mexican West Coast Rattlesnake
One of the largest rattlesnakes in the world, it produces large amounts of highly toxic venom.
South American Rattlesnake
The most venomous of all rattlesnakes, it lives mainly in South America but also turns up in Mexico, Columbia, Venezuela, Brazil, Bolivia, Paraguay, Argentina, Peru and Guyana. The likelihood of death from its bite can reach 75 percent if not treated. Their venom also causes vision problems and even permanent blindness.
Golden Lancehead
Only found on a small island called lha da Queimada Grande, also known as Snake Island, off the coast of Brazil. Its venom is considerably stronger than that of other lancehead snakes.
Common Lancehead
Mostly found near banana and coffee plantations, where it preys on small animals. In the past, lancehead bites meant near-certain death. Today, antidotes are effective, if administered in time.
And finally, we come to:
Australia
Inland Taipan
The most venomous snake in the world, it is estimated that the venom from a single bite can kill 100 grown men or kill one man in about 45 minutes.
Reclusive and rare, the inland taipan hides out in remote, rocky terrain. It hunts the long-haired rat in confined burrows. To finish off prey quickly, it injects more than 40,000 times the amount of venom needed to kill a 200g rat.
The inland taipan, the world’s most venomous snake. Photo: theaustralian.com.au
The snake’s neurotoxic poison causes gradual paralysis and compromises breathing. As if this were not enough, its venom carries an anticoagulant, so that victims can also haemorrhage internally to death. Myotoxins also dissolve muscle and other tissues, and the wound can cause significant kidney damage. Click here to see the late Crocodile Hunter Steve Irwin’s encounter with the inland taipan.
Eastern Brown Snake
Found along Australia’s east coast, from far north Queensland down through New South Wales, Victoria and into South Australia, the Eastern brown snake is responsible for approximately 60 percent of the fatal snakebites in this country. Adults grow two metres long and are swift and aggressive. They have the second-most venomous bite of any terrestrial snake, after the inland taipan. When threatened, this snake raises its body off the ground, in a characteristic “S” shape.
Eastern brown snake. Photo: naturalist.org
Western Brown Snake
Also known as the Gwardar, the Western brown snake is widespread across Australia. It favours dry habitats as well as eucalyptus forests, woods and grasslands. While its venom isn’t as potent as its eastern cousin, the Western Brown delivers a bite with three times as much venom, triggering nausea, headaches and abdominal pain. Cats and dogs can experience paralysis.
Tiger Snake
Variations in colour and pattern make the tiger snake difficult to identify, but as its name suggests, it is usually striped. Found throughout southern parts of Australia, its highly neurotoxic venom has a mortality rate between 40 and 60 percent, if untreated. Tiger Snakes are a protected species throughout most of Australia.
Coastal Taipan
In contrast to its timid cousin, coastal taipans are aggressive and possess the third most toxic venom of any terrestrial snake in the world. Dwelling in northern and eastern Australia, they grow up to two metres long and deliver their venom through 12mm fangs, the longest of any Australian snake. When threatened, the coastal taipan strikes ferociously, injecting a neurotoxin that rapidly causes headaches, nausea/vomiting, convulsions, paralysis, internal bleeding and kidney damage.
Rounding out the top 10 species not to meet in a dark alley are the common death adder, red-bellied black snake, mulga snake, small-eyed snake and lowland copperhead.
If you travel through areas inhabited by such formidable creatures, there are some common-sense precautions:
Avoiding Snakes and Bites
- Bites mainly occur when the snake is disturbed or provoked. Obviously, the safest way not to be bitten is to avoid these snakes.
- Be careful where you put your hands and feet. Snakes like to hide where they can’t be seen, such as holes in the ground, rock crevices, fallen logs or long grass. Use a headlamp at night, because many snakes are active after dark.
- Wear protective clothing. Thick clothing such as jeans and boots offer some protection.
- Almost one in five snakebites happen when people provoke the snake. Always give the snake space to move away or go around it.
- Snakes can’t hear well but can sense vibrations in the ground. In the bush, make noise and stomp your feet to scare off any nearby snakes.
When in doubt, seek treatment
Snakebites don’t always look like snakebites, and people sometimes don’t immediately realize that they’ve been bitten. The bite may look like a slight scratch, or show just minor swelling; there may be no pain or other symptoms. Even so, always perform first aid and seek treatment.
Snakebite symptoms can include:
- Puncture marks (or small, very visible scratches)
- Difficulty breathing
- Bruising or swelling
- Headache, confusion or dizziness
- Blurred vision, muscle weakness or collapse
- Nausea, vomiting or abdominal pain
- Irregular heartbeat
- Tingling, stinging or burning skin
- Bleeding or paralysis
In 2017, Australia’s Royal Flying Doctor Service completed the Australian Snakebite Study, involving over 1,500 patients and more than 10 years worth of snakebite data. The results challenged many long-held perceptions about where snake attacks occur and how to treat them.
The most important dos and don’ts include:
- Do NOT wash the area of the bite or try to suck out the venom. It is extremely important to retain traces of venom for use with venom identification kits.
- Do NOT incise or cut the bite or apply a high tourniquet. Cutting or incising won’t help. High tourniquets are ineffective and can be fatal if released.
- Do bandage firmly, splint and immobilize to stop the spread of venom. All major medical associations recommend slowing the spread of venom by placing a folded pad over the bite area and then applying a firm bandage. It should not stop blood flow to the limb or constrict the veins. Only remove the bandage in a medical facility, as the release of pressure will cause a rapid flow of venom through the bloodstream.
- Do NOT allow the victim to walk or move their limbs. Use a splint or sling to minimize all movement. Put the patient on a stretcher or bring transportation to the patient.
- Do seek medical help immediately, as death or permanent injury can sometimes occur within a few hours.
The new study also prompted the Service to reverse previous long-standing advice about the importance of identifying the colour and type of snake. Tracey King, Senior Flight Nurse, with the Service noted: “Recent advances in medication mean we can now treat any snakebite with a generic polyvalent antivenom, so identification is no longer necessary.”
Many variables can affect the outcome of a snake envenomation, including the size, age and health of both the snake and the victim. The body temperature, even the mood of a particular snake, in addition to its toxicity and quantity of venom delivered, all make a big difference in the outcome.
The final word: Don’t let the risk of snakebite keep you from enjoying the outdoors. By researching the area and taking sensible precautions, you can significantly reduce the chance of getting bitten. In extreme cases, it might just save your life.
