This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!
If a lethally poisonous snake bites another lethally poisonous snake of the same species does the bitten snake suffer healthwise or die? – Ella, age 10, Wagga Wagga.
That’s a great question.
If a venomous snake is bitten by another venomous snake of the same species, (for example during a fight or mating), then it will not be affected.
However, if a snake is bitten by a venomous snake of another species, it probably will be affected.
This is probably because snakes have evolved to be immune to venom from their own species, because bites from mates or rivals of the same species probably happen fairly often.
But a snake being regularly bitten by another snake from a different species? It’s unlikely that would happen very often, so snakes haven’t really had a chance to develop immunity to venom from other species.
Many people believe that snakes are immune to their own venom so that they don’t get harmed when eating an animal it has just injected full of venom.
But in fact, they don’t need to be immune. Scientists have found that special digestive chemicals in the stomachs of most vertebrates (animals with backbones) break down snake venom very quickly. So the snake’s stomach can quickly deal with the venom in the animal it just ate before it has a chance to harm the snake.
People that have snakes as pets often see this. If one venomous snake bites a mouse and injects venom into it, for example, you can then feed that same dead mouse to another snake. The second snake won’t die.
By the way, scientists usually use the word “venomous” rather than “poisonous” when they’re talking about snakes. Many people often mix those words up. Poisons need to be ingested or swallowed to be dangerous, while venoms need to be injected via a bite or a sting.
Some snakes can inject their toxins into their prey, which makes them venomous. However, there seem to be a couple of snake species that eat frogs and can store the toxins from the frogs in their body. This makes them poisonous if the snake’s body is eaten. Over time, many other animals will have learned that it is not safe to eat those snakes, so this trick helps keep them safe.
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Despite the common belief that Australia has some of the most venomous snakes in the world, our new research shows being bitten by a snake is uncommon in Australia and dying from a snakebite is very rare.
And of the few unlucky people to collapse after venom enters their bloodstream, a bystander performing cardiopulmonary resuscitation (CPR) is the most likely thing to save them.
These are just some of the findings from 10 years of data from the Australian Snakebite Project published today in the Medical Journal of Australia.
Although many people go to hospital with a suspected snakebite, many do not turn out to have envenomation (when venom enters the bloodstream) after all.
In more than 90% of cases people are bitten by a non-venomous snake, venom is not injected when the snake bites (known as a “dry bite”) or are not even bitten by a snake (known as a “stick” bite).
Our analysis of about 1,548 cases of suspected snakebites from all around Australia, showed there were on average just under 100 snake envenomations a year, and about two deaths a year.
The most common snakebites were from brown snakes, then tiger snakes and red-bellied black snakes. Brown snakes were responsible for 40% of envenomations. Collapsing, then having a heart attack out of hospital was the most common cause of death (ten out of 23), and most deaths were from brown snakes.
Venom from a snakebite travels via the lymphatic system to the bloodstream. There, it circulates to nerves and muscles where it can cause paralysis and muscle damage. In the blood itself, the venom destroys clotting factors, which makes the blood unable to clot, increasing the risk of bleeding.
In the most severe cases, most commonly in brown snake bites, someone can collapse because they have low blood pressure (we don’t know for certain what causes the low blood pressure). In this situation, insufficient blood is pumped around the body for the brain and other vital organs.
Clearly the accurate diagnosis of snake envenomation and the timely administration of antivenom are essential to treating snakebites in hospital.
But when people collapse, CPR will keep the blood circulating to the vital organs – and is life-saving – however inexpertly a bystander performs it.
In other words, we found basic first aid before people reached hospital, of which bystander CPR is one, may be more important than any changes in how people are treated in hospital to improve people’s chance of survival. People who survived after collapsing received CPR on average within one minute of being bitten compared with 15 minutes for those who died.
Our study also showed that in most cases, people used other first-aid measures (pressure bandages and immobilising both the limb and the patient). These aim to prevent the venom travelling from the bite site, via the lymphatic system, to the bloodstream.
Our study confirmed the role of antivenom in treating snakebites and the need for it to be administered before irreversible damage is done to the nervous system and paralysis occurs.
However, we found one in four patients given antivenom had an allergic reaction to it and about one in 20 have severe anaphylaxis requiring urgent treatment.
So it is essential only patients with snake envenomation, and not just a suspected snakebite, are treated with antivenom. We found 49 patients (around 6%) were given antivenom unnecessarily, out of the total 755 patients who received it.
So we need to find ways to make sure patients get antivenom as early as possible. This requires laboratory tests that can identify patients with snake envenomation in the first couple of hours after the bite.
It is also essential anyone bitten by a snake or suspected to be bitten by a snake seeks immediate medical attention and goes to hospital by ambulance.
But the best thing is to avoid being bitten in the first place:
Summer is traditionally Australia’s snake bite season, when both snakes and people become more active. The human death toll is now admirably low, but it wasn’t always so.
Although colonial statistics are highly unreliable, in 1882-1892 about 11 people died from snake bites across Australia a year. Since then, the continent’s population has grown from 2.2 million to 24.3 million, yet on average just two people died from snake bites a year in 2001–2013. While improved transport, communications and ambulance services have all contributed, so have the first aid and medical measures used to counteract snake venom.
A typical case from 1868 suggests the complexity – and desperation – of colonial remedies. When Victorian railway workers killed a brown snake at Elsternwick Station, they threw its body to stationmaster John Brown. Either the serpent was still alive, or Brown brushed its fangs, when he struck it “with an angry gesture”. The usual signs of envenomation (venom injected into the skin) soon appeared: vomiting, physical weakness then creeping paralysis followed by “coma”. Death, seemingly, was inevitable.
The stationmaster was rushed to nearby Balaclava, where surgeon George Arnold tied a ligature (tourniquet) around Brown’s arm before slicing out the bite site, hoping to remove the venom. He then poured ammonia (a hazardous chemical used today in cleaning) onto the wound to neutralise any remaining venom before urging Brown to drink six ounces (175mL) of brandy to stimulate his circulation.
He waved pungent smelling salts under Brown’s nose then applied a paste-like poultice of mustard to his patient’s hands, feet and abdomen to alleviate internal congestion. Further stimulation followed via electric shocks before the staggering, semi-conscious stationmaster was marched up and down to keep him awake – and alive. Brown, nevertheless, kept deteriorating.
Arnold urgently summoned the colony’s only medical professor, George Halford at Melbourne University, who reluctantly agreed to apply his new snake bite remedy. He opened a vein in Brown’s arm and injected ammonia directly into the bloodstream. The stationmaster revived almost immediately, leading another doctor to assert “the injection of Ammonia saved the man’s life” (do not try this at home).
John Brown’s treatment followed a pattern familiar across Australia from 1800 into the 1960s. While many of the 1868 interventions now seem bizarre – or downright dangerous – they made sense in historical context. Until well into the 20th century, snake bite treatments alternated between three fundamental approaches.
In common with today’s understanding, most European settlers, and many Indigenous cultures, considered venom to be an external “poison” that moved through the body. Physical measures such as ligature or suction were thus common to expel venom or limit its circulation.
A second strand of remedies, from mustard poultices to injected ammonia, sought to counteract its ill effects in the body, often by stimulating heart function and blood flow.
The third approach was to directly neutralise venom itself, for instance, pouring ammonia onto the bite.
Until the 1850s, physical measures dominated, while the next 50 years were the heyday of opposing-action treatments. When Halford’s intravenous ammonia fell from favour (as it didn’t seem to work), it was replaced in the 1890s by injections of another notorious poison: strychnine. At first even more popular than ammonia, this highly toxic plant-based poison was blamed for killing more patients than it saved. Yet by far the most popular colonial remedy, both with practitioners and patients, was drinking copious quantities of alcohol, especially brandy.
The third approach, directly neutralising venom, underlay both Australia’s hugely popular folk “cures” and the novel “antivenene” technology developed in the 1890s. Now they are known as antivenoms and are created by injecting venom into (generally) horses, prompting an immune response, then purifying antibodies from their blood to inject into snake-bitten patients.
But antivenenes suffered a slow gestation in Australia. The first, targeting black snake venom, was developed in 1897; experimental tiger snake antivenene followed in 1902. But antivenenes are tricky to produce, distribute and store. They also proved difficult to administer, sometimes provoking life-threatening anaphylactic reactions (a severe allergic response).
It wasn’t until 1930 that commercial tiger snake antivenene came onto the Australian market.
Other injections targeting a wider range of serpents. “Polyvalent” antivenene, which is effective against multiple venoms, only emerged from the mid-1950s. Meanwhile, patients continued to undergo various first-aid measures, particularly ligatures and Condy’s crystals (potassium permanganate, used to clean wounds) applied to the bite in the hope of inactivating venom.
Current snake bite management only stabilised in the 1980s. Two developments were key: rapid tests to identify the injected venom and a new first-aid strategy.
Scientist Struan Sutherland pioneered the “pressure immobilisation technique”. This recommends tightly wrapping a bandage around the bitten region, adding a splint and minimising movement to slow venom spread.
Not washing or cutting the bite site leaves a venom sample to aid identification and so choose the most appropriate antivenom.
But today’s management is still being evaluated because both venoms and treatments still pose clinical challenges, including severe reactions and long-term damage.
And just as in 1868, two eternal questions remain critical: was it truly a deadly serpent, and did it inject enough venom to kill?