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Deadly Snake Hunted for Lifesaving Venom

Brian Handwerk
for National Geographic News
March 10, 2003
 
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In Australia, life-threatening poisonous animals have always posed a hazard to humans. But some of the most dangerous also act as lifesavers. Such is the case with the notorious death adder, a snake that's essential to the production of lifesaving snakebite antivenins.

The National Geographic Channel tags along with snake wranglers from the Australian Reptile Park in Somersby, New South Wales, as they hunt death adders for their valuable and deadly venom. Death Adder Duet is an installment in the Snake Wranglers series, which brings viewers face-to-fang with the planet's most compelling snakes.

For more than 50 years, the staff of the Australian Reptile Park has raised and milked hundreds of venomous spiders and snakes—including the death adder—for their poisonous venom in order to create life-saving medicines.

The park's venom-milking program is the only supplier of venom to Melbourne's Commonwealth Serum Laboratories—makers of antivenins crucial to treating snakebite victims.



The work is time-consuming and not without hazard. Hundreds of milkings are necessary to create a single dose of antivenin. It's a difficult job, but one that pays tremendous dividends for public health. As John Weigel, director of the Australian Reptile Park, notes, the program helps save hundreds of lives each year.

"Producing the venom that's used to make the antivenin, that's part of the soul of us, part of our heritage and what we do," Weigel told National Geographic News. "We've done it for 55 years and it saves perhaps 280 to 300 lives a year. That's something we feel really good about."

From Deadly Venom to Healing Medicine

Thanks to the widespread availability of effective antivenins, snakebite fatalities in Australia have become rare in recent decades.

The nation's antivenin program suffered a setback two years, however, after a devastating fire raged through the Australian Reptile Park. The blaze gutted much of the park and killed most of its captive animals—including snakes used in the venom-milking program. Since the catastrophe, staff members have traveled Australia to collect venomous snakes in order to rebuild the program.

Death adder venom remains in particularly short supply. Snake wranglers are combing Australia for the reclusive reptiles. "We need something like 50 to 60 death adders to milk every two weeks in order to provide a sufficient quantity of venom," Weigel estimated.

Like that of other snakes, death adder venom, is a form of saliva. When a venomous snake bites, it injects venom into its victim through hollow fangs—though this does not happen with every bite.

In the milking process, a snake is prompted to bite through a latex membrane stretched over a glass beaker. Venom is collected in the beaker then later dried, weighed, and packaged by staff members wearing protective masks.

Dried venom is sent to the Commonwealth Serum Laboratories, in Melbourne, Victoria. Over long periods of time, some 250 huge Percheron horses are injected with tiny but increasing amounts of venom (the animals are unharmed). The horses produce natural antibodies to counteract the small amounts of poison in their systems. After about a year, blood plasma is extracted from the horses in a process as simple a human blood donation—plasma rich with antibodies that can neutralize snake venom.

Death Adders Hunted For Potent Venom

Capturing a death adder is difficult and dangerous. The snakes grow up to 75 centimeters (29.5 inches) long and are rather reclusive. They hunt by ambush—sometimes partially buried in sand, soil, or leaves—waiting for lizards, birds, or other small animals beneath low bushes and shrubs. The camouflaged snake uses the thin tip of its brightly-colored tail as a lure before striking its prey with large fangs six to eight millimeters (0.2 to 0.3 inches) long.

The several species of death adders are often ranked among the world's most deadly snakes—although their reputation may be a bit misleading. "These popular listings are often based on the potency of the snake's venom— the quantity of reconstituted dried venom it would take to kill a laboratory mouse or a human." Weigel explained.

While death adder venom is highly potent, such rankings often overlook important mitigating factors when determining how likely a human is to survive an encounter with the snake. Factors include the amount of venom typically injected during a bite, the likelihood of a death adder to strike and bite, and even the odds of encountering the snake in the wild. So while death adders rank among the most deadly snakes, the risks they pose to humans are not quite so high. This tempered threat is due to the high success rate of antivenin treatment and also decreased instances of human-snake encounters as the death adder's population has declined.

Nonetheless, hunting the snakes is dangerous. If left untreated, the death adder's bite is deadly. "It's one of those snakes that, if it bites and envenomates you, you can certainly die," said Weigel.

The snake's venom contains neurotoxins that can cause major respiratory paralysis within 6 hours of receiving a bite. "An untreated bite has a high death rate," Weigel explained. "In New Guinea, where we don't have much antivenin, the death rate remains something like 50-50."
 

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