Mystery of California's killer rattlesnakes solved

January 28, 2014
Mystery of California's killer rattlesnakes solved
Southern Pacific Rattlesnake. Credit: Chip Cochran.

( —A surge in snakebite deaths caused by one of North America's most dangerous snakes has been baffling doctors, but new research may hold the key to saving lives.

A study of Southern Pacific Rattlesnake , led by The University of Queensland's Associate Professor Bryan Fry, has found that by knowing the location where a person was bitten, doctors are better equipped to offer life-saving treatment.

"If clinicians know where a person was bitten, they will know how the patient is likely to be affected," Dr Fry said.

"These snakes live in habitats as diverse as the isolated Catalina Island, the high-altitude San Jacinto mountains, the grassy hills of Loma Linda and the desert transition zone of Phelan.

"In a two-hour drive from the desert floor to the top of the San Jacinto Mountains, the venom goes from destroying the blood to frying the nerves instead.

"Over millions of years, living in these very different habitats has led to specialised venom chemistry which needs to be understood to effectively treat snakebite patients."

Dr Fry and his team sampled venoms from four diverse regions, including Catalina Island, and analysed the venom chemistry and evolution.

The team found significant differences between populations.

"Mapping the geographical venom variation of this species has important implications for treating bites," he said.

Dr Fry said the study disproved previous reports that recent, rapid change in the venom was the cause, leading to increased reports of unusual and highly toxic effects in patients.

"Clinicians had been at a loss to explain what was happening," Professor Fry said.

"However, rather than changing rapidly, the venom varies dramatically between different populations of the snakes due to long-term adaptation to different environments."

Dr Fry also said reports of unusual effects were likely due to better record keeping and reporting and changes in human behavior, rather than any recent changes to the venom.

"New housing estates are being built on what used to be remote areas, and people with low snake awareness are coming into close contact with Southern Pacific Rattlesnakes," he said.

"Many times when a patient presents at the hospital it is because they tried to kill the snake and were bitten in the process."

Explore further: Vintage venoms lose none of their bite

More information: Kartik Sunagar, Eivind A.B. Undheim, Holger Scheib, Eric C.K. Gren, Chip Cochran, Carl E. Person, Ivan Koludarov, Wayne Kelln, William K. Hayes, Glenn F. King, Agosthino Antunes, Bryan Grieg Fry. "Intraspecific venom variation in the medically significant Southern Pacific Rattlesnake (Crotalus oreganus helleri): Biodiscovery, clinical and evolutionary implications." Journal of Proteomics, Available online 24 January 2014, ISSN 1874-3919,

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not rated yet Jan 29, 2014
What surge of snakebite deaths is the writer talking about? What doctors are baffled? In California the last fatal bite published was 2012. In the US there's only on average 12 fatal snake bites a year and where half are from rattlesnakes, it's rare the Southern Pacific is named. Dr Frys work is not an issue, but the writer's ( I say that loosely) attempt to explain it, is laughable. Yes snakes evolve like all other animals and by the way doctors treating snake bites are not ignorant to specie habitat facts.

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