GREEN VALLEY — T.J. Lundgren didn’t see the rattlesnake coiled under the prickly pear.
The Green Valley firefighter and paramedic was pulling weeds near his fire station as part of a regular weekly maintenance day to keep the grounds tidy. As he reached down to grab a handful of grass surrounding a cactus, he felt a prick on his left hand and jumped back.
“I looked down at my hand and there was a small drop of blood,” he said. “I thought maybe I got poked by the cactus. Then I heard a rattle.”
Peering cautiously around the prickly pear, Lundgren saw the perpetrator: a western diamondback rattlesnake, perhaps 2 feet long. He headed inside to give his co-workers the bad news.
“I knew from my training that you want to stay calm,” Lundgren said. “You don’t want to elevate your heart rate at all.”
He removed his watch, knowing that his hand was likely to swell. His co-workers marked the bite area with a permanent marker to record the initial amount of swelling. Doctors use this technique to document the venom’s toxic march through the affected limb.
As Lundgren sped to the University of Arizona Medical Center in the back of an ambulance, he silently hoped that the rattlesnake had delivered a “dry bite,” meaning no venom had been injected. No such luck.
“By the time we got to the hospital, within maybe 45 minutes, the swelling was down past my wrist,” he said. When Lundgren arrived, doctors began evaluating his condition to decide what to do next.
Science of a bite
As spring marches on, reptiles throughout southern Arizona are emerging from hibernation. For Chuck Wunder, operations division chief of the Green Valley Fire District, that means an uptick in call volume from area residents seeking removal assistance.
“When the weather hits the mid-80s, we start picking up,” he said, “and typically for us, that is late March or early April.”
Wunder said people should avoid wrangling reptiles on their own. His team is trained in snake removal and can safely relocate venomous creatures to remote, unpopulated areas.
But what happens in a case like Lundgren’s, when someone is in the wrong place at the wrong time, and a bite occurs?
“Essentially,” Dr. Leslie Boyer said, “a rattlesnake has venom for the purpose of making lunch hold still and go down easier.” Boyer is the director of the University of Arizona’s VIPER Institute, which studies the genes of venomous animals to develop better drugs and diagnostic tools.
Boyer said rattlesnake venom contains chemicals that can make a small animal faint to keep it from running away. Other components act as a meat tenderizer, breaking down tissue as the venom spreads through the victim.
Part of the venom is also “basically digestive juices,” she said, “similar to what the human pancreas would put into a steak.” These juices allow snakes to use their victims’ own circulatory system to aid in digestion before dinner, Boyer said, “which is a handy thing because they can’t chew.”
Art of antivenin
Back at the hospital, doctors were preparing to administer antivenin to Lundgren. Antivenin, according to Boyer, is used to describe brand name, biologically derived venom remedies. Personally, she prefers the general term “antivenom,” pointing to its adoption by the World Health Organization and other groups, including the VIPER Institute.
“There is so much argument about it that you know it’s a trivial thing,” she said.
Indeed, UAMC doctors were probably not debating the issue as they diagnosed Lundgren. The more pressing issue was how much antivenin they should use to begin treatment.
“It’s not a science,” Boyer said. “It’s more of an art.” There is no simple diagnostic test that allows doctors to determine how much antivenin to give and how fast to give it. That’s partly because the amount of venom a snake delivers can vary greatly, “for reasons that only the snake knows,” she said.
The goal of an emergency room doctor is to neutralize as much venom as possible right away. But the decision is based on indirect evidence, such as the patient’s condition or other indicators like blood platelet levels. One of VIPER’s long-term goals is to improve diagnostic tests to make the use of antivenom less of an art and more of a science.
The doctors at UAMC decided to start Lundgren with 10 vials of antivenin and see how he reacted. It had been two hours since the rattlesnake struck, and the swelling had advanced up his forearm to his bicep. “The pain was getting pretty unbearable,” he said. “It felt like someone was just squeezing my bones down my whole arm.”
Doctors responded by elevating his hand to distribute the venom evenly throughout his damaged limb. If the swelling didn’t stop soon, a fasciotomy might be required, meaning Lundgren’s arm would be sliced open to relieve the pressure.
Antivenin is created by giving small doses of venom to mammals like horses or sheep. The animals produce immune responses to each injection, and over the course of many months, they build up antibodies to protect themselves. The VIPER Institute reassures concerned animal lovers that this really isn’t such a bad career choice for domestic animals.
“The idea,” Boyer said, “is to give them a low enough amount that they don’t get sick from it.” Eventually, she said, the animals become so immunized that “if they were bitten by a whole bunch of snakes, all at once, they could shrug it off.”
At that point, the animal becomes a blood donor. Its antibodies are separated, purified and used to create antivenin. In order to prolong shelf life, hospitals store it in powder form and reconstitute it as needed. Although U.S. antivenin supplies vary each year, Boyer said southern Arizona hospitals always have enough on hand to administer a starter dose and can quickly obtain more as needed.
As for Lundgren, the initial dose of 10 antivenin vials finally stopped the swelling. He avoided the gruesome fasciotomy, but doctors ended up administering an additional six vials over the next 24 hours to fully neutralize the rattlesnake’s effects. He was released from the hospital after two-and-a-half days, and gradually regained use of his hand with the help of a physical therapist. It would be another month before his arm fully returned to normal.
The VIPER Institute is continuing to work on improving the treatment for venomous bites and stings. In 2011, Boyer’s team helped secure the first FDA approval for scorpion antivenin. It marked the culmination of 12 years of cross-border collaboration with scientists in Mexico.
In the meantime, Lundgren has some simple advice to avoid an unfortunate encounter with a venomous snake: Check places you can’t see before sticking your hands or feet there.
“If you can’t see the ground,” he said, “just double-check.”
Be snake smart
• Avoidance is the best policy. The Arizona Poison & Drug Information Center says 50 to 70 percent of reptile bites it investigates occur when someone is trying to “kill, capture or harass” a venomous animal. This includes dead snakes, which may still have the reflexes to strike.
• Don’t put limbs where you can’t see. Be particularly wary of placing your hands and feet in deep grass, weeds, woodpiles and rocks.
• Call for assistance. Creatures you see in your back yard are probably just “passing through,” according to the Arizona Poison & Drug Information Center.
• Seek help immediately if bitten. Call 911 or head to the nearest medical facility. Field remedies like constricting bands and venom extractors generally do more harm than good and should be avoided. Try to stay calm, and remove any clothing or jewelry from the affected area. Southern Arizona rattlesnake antivenin is one-size-fits-all, so there is no need to risk capturing a snake that has bitten someone.
• For more information: Arizona Poison & Drug Information Center, 1-800-222-1222 or online: www.pharmacy.arizona.edu/centers/arizona-poison-drug-information-center.