Hissstory: how the science of snake bite treatments has changed

Peter Hobbins, University of Sydney

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.

Complex colonial remedies

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).

Name your poison

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 slow premiere of antivenoms

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.

Two eternal questions

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?

Peter Hobbins, ARC DECRA Fellow, University of Sydney

This article was originally published on The Conversation. Read the original article.

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Meet El Niño’s cranky uncle that could send global warming into hyperdrive

Ben Henley, University of Melbourne; Andrew King, University of Melbourne; Chris Folland, Met Office Hadley Centre; David Karoly, University of Melbourne; Jaci Brown, CSIRO, and Mandy Freund, University of Melbourne

You’ve probably heard about El Niño, the climate system that brings dry and often hotter weather to Australia over summer.

You might also know that climate change is likely to intensify drought conditions, which is one of the reasons climate scientists keep talking about the desperate need to reduce greenhouse gas emissions, and the damaging consequences if we don’t.

El Niño is driven by changes in the Pacific Ocean, and shifts around with its opposite, La Niña, every 2-7 years, in a cycle known as the El Niño Southern Oscillation or ENSO.

But that’s only part of the story. There’s another important piece of nature’s puzzle in the Pacific Ocean that isn’t often discussed.

It’s called the Interdecadal Pacific Oscillation, or IPO, a name coined by a study which examined how Australia’s rainfall, temperature, river flow and crop yields changed over decades.

Since El Niño means “the boy” in Spanish, and La Niña “the girl”, we could call the warm phase of the IPO “El Tío” (the uncle) and the negative phase “La Tía” (the auntie).

These erratic relatives are hard to predict. El Tío and La Tía phases have been compared to a stumbling drunk. And honestly, can anyone predict what a drunk uncle will say at a family gathering?

What is El Tío?

Like ENSO, the IPO is related to the movement of warm water around the Pacific Ocean. Begrudgingly, it shifts its enormous backside around the great Pacific bathtub every 10-30 years, much longer than the 2-7 years of ENSO.

The IPO’s pattern is similar to ENSO, which has led climate scientists to think that the two are strongly linked. But the IPO operates on much longer timescales.

We don’t yet have conclusive knowledge of whether the IPO is a specific climate mechanism, and there is a strong school of thought which proposes that it is a combination of several different mechanisms in the ocean and the atmosphere.

Despite these mysteries, we know that the IPO had an influence on the global warming “hiatus” – the apparent slowdown in global temperature increases over the early 2000s.

Global temperatures are on the up, but the IPO affects the rate of warming.
Author provided, data from NOAA, adapted from England et al. (2014) Nat. Clim. Change

Temperamental relatives

When it comes to global temperatures we know that our greenhouse gas emissions since the industrial revolution are the primary driver of the strong warming of the planet. But how do El Tío and La Tía affect our weather and climate from year to year and decade to decade?

Superimposed on top of the familiar long-term rise in global temperatures are some natural bumps in the road. When you’re hiking up a massive mountain, there are a few dips and hills along the way.

Several recent studies have shown that the IPO phases, El Tío and La Tía, have a temporary warming and cooling influence on the planet.

Rainfall around the world is also affected by El Tío and La Tía, including impacts such as floods and drought in the United States, China, Australia and New Zealand.

In the negative phase of the IPO (La Tía) the surface temperatures of the Pacific Ocean are cooler than usual near the equator and warmer than usual away from the equator.

Since about the year 2000, some of the excess heat trapped by greenhouse gases has been getting buried in the deep Pacific Ocean, leading to a slowdown in global warming over about the last 15 years. It appears as though we have a kind auntie, La Tía perhaps, who has been cushioning the blow of global warming. For the time being, anyway.

The flip side of our kind auntie is our bad-tempered uncle, El Tío. He is partly responsible for periods of accelerated warming, like the period from the late 1970s to the late 1990s.

The IPO has been in its “kind auntie” phase for well over a decade now. But the IPO could be about to flip over to El Tío. If that happens, it is not good news for global temperatures – they will accelerate upwards.

Models getting better

One of the challenges to climate science is to understand how the next decade, and the next couple of decades, will unravel. The people who look after our water and our environment want to know things like how fast our planet will warm in the next 10 years, and whether we will have major droughts and floods.

To do this we can use computer models of Earth’s climate. In our recently published paper in Environmental Research Letters, we evaluated how well a large number of models from around the world simulate the IPO. We found that the models do surprisingly well on some points, but don’t quite simulate the same degree of slow movement (the stubborn behaviour) of El Tío and La Tía that we observe in the real world.

But some climate models are better at simulating El Tío and La Tía. This is useful because it points the way to better models that could be used to understand the next few decades of El Tío, La Tía and climate change.

However, more work needs to be done to predict the next shift in the IPO and climate change. This is the topic of a new set of experiments that are going to be part the next round of climate model comparisons.

With further model development and new observations of the deep ocean available since 2005, scientists will be able to more easily answer some of these important questions.

Whatever the case, cranky old El Tío is waiting just around the corner. His big stick is poised, ready to give us a massive hiding: a swift rise in global temperatures over the coming decades.

And like a big smack, that would be no laughing matter.

Ben Henley, Research Fellow in Climate and Water Resources, University of Melbourne; Andrew King, Climate Extremes Research Fellow, University of Melbourne; Chris Folland, Science Fellow, Met Office Hadley Centre; David Karoly, Professor of Atmospheric Science, University of Melbourne; Jaci Brown, Senior Research Scientist, CSIRO, and Mandy Freund, PhD student, University of Melbourne

This article was originally published on The Conversation. Read the original article.