Snakebites rising, tougher to treat
To add insult to injury, Riverside County rattlers are state's most lethal, an expert says:
By MARK MUCKENFUSS
The Press-Enterprise
Doctors who treat rattlesnake bites in Southern California say they are seeing more bites in recent years and an increase in more-serious cases where patients don't fully respond to antivenin treatments.
Inland Empire residents may be at even greater risk, since experts say one local rattler has the most potent venom of any in the state.
Hard data is elusive because there is no mandatory reporting system, but anecdotal information from experts seems to indicate an increase in incidents. Some blame new housing construction in outlying areas for encroaching on the natural habitat of rattlesnakes.
Late April and May is the most active period for snakes in Southern California.
Story continues below.
Last weekend, Mike Zerwekh, of Moreno Valley, was bitten by a rattlesnake in the hills southwest of Corona. On Monday, Sherry Brown was bitten near her home in the High Desert community of Lucerne Valley. Both were airlifted to Loma Linda University Medical Center for treatment.
Loma Linda emergency room physician Dr. Sean Bush is recognized as a specialist in treating snakebites. He has appeared on the television show "Venom ER."
Zerwekh identified the snake that bit him as a Southern Pacific -- the snake Bush blames most for the rising number of serious bites he is seeing.
"The Southern Pacific has long been overlooked as one of the most, if not the most dangerous snakes in Southern California or even all of California," Bush said.
What makes treating the bites a challenge, he said, is that the venom from one Southern Pacific rattler may be different from that of another and many of the components of the venom remain unknown.
"The venom is real variable," he said.
Most dangerous is the Mojave toxin, named for the Mojave rattlesnake found in desert areas. Mojave toxin has also been found in some Southern Pacific rattlesnakes.
In addition, Bush and other experts said, one person's reaction to a snakebite can be markedly different from another's, even if they were subjected to the same venom.
Unresponsive Toxins
Experts say some toxins are showing up in snakebites that are not responsive to antivenin.
Bush said scientists recently identified a compound in some snake venom called hellerase.
"It's possible the antitoxin we use doesn't adequately neutralize that toxin," he said. "We're suspecting (hellerase) could be related to uncontrollable muscle twitching after the bite."
The twitching made one patient look as if he had something crawling under his skin. While not damaging, Bush said, "It just keeps on going. In that case, it lasted for five days."
Richard Clark is director of toxicology at UC San Diego Medical Center. He says he and his colleagues have seen a similar trend.
"All of us seem to have the general impression that we've seen some sicker patients," Clark said. He has noticed more patients with symptoms related to neurological toxicity, such as rapid heartbeat and low blood pressure.
Clark said it's hard to know what the real numbers are. He heads the San Diego division of the California Poison Control System, a statewide agency that recorded 269 snake bites last year.
"That's the tip of the iceberg," Clark says. "A lot of the people I know don't call the poison center to report cases. I have a colleague who sees a lot of snakebites and he never calls us."
Clark said he suspects the problem is mostly the result of more home building in remote foothill areas, which are prime habitat for the Southern Pacific rattlesnake.
"We have kids bitten in school yards because they're building homes right on the edge of a canyon where there are rattlesnakes," he said. In addition, the landscaping of these areas with greener vegetation and water draws even more wildlife, including snakes.
Venom Not Evolving
Some scientists have speculated snake venom may actually be changing in Southern California. They theorize that rodents -- a snake's primary food -- have developed a resistance to certain toxins and that there is a natural selection for snakes with more potent venoms. But William Hayes, a professor of earth and biological science at Loma Linda University, said he sees no evidence of that.
"Venom is not rapidly evolving to become more toxic," Hayes said. "That's not the way evolution works."
Hayes also likes to debunk the myth that baby rattlesnakes are more dangerous. It's true, he said, that the potency of venom decreases as a snake ages -- the Mojave rattlesnake is an exception to this -- but bigger snakes have more venom to inject. It's also untrue, he said, that baby rattlesnakes cannot control the amount of venom they inject.
Whether a snake is small or large, it appears anyone bitten in the Inland region may face a greater risk than if they encountered a rattlesnake elsewhere.
Elda Sanchez is assistant director of the Natural Toxins Research Center at Texas A&M University. She recently studied five different Southern Pacific snakes from Riverside and San Bernardino counties.
"The snakes in Riverside County are more lethal than in other counties of California," Sanchez said.
She said scientists are also looking at the effectiveness of current antivenins.
Don Boyer, curator of herpetology at the San Diego Zoo, said about 10 years ago a different pharmaceutical company began producing the majority of antivenin used in hospitals.
Antivenin is created by injecting other animals -- primarily horses -- with small amounts of venom and then harvesting the antibodies produced to battle the venom. A broad mix of venoms is combined for the initial injection to obtain an antivenin that will neutralize a wide range of potential bites. Some speculate that the current antivenin in use may not be broad enough.
"This new antivenin is molecularly much smaller and I think there may be a slightly different species composition involved," Boyer said. Studies are under way to determine whether a different antivenin produced in Mexico is more effective.
Boyer said he doesn't think the public needs to be overly alarmed. Snake bites are still rare. Most occur when people unnecessarily molest snakes.
"Rattlesnakes are part of the environment and very important," Boyer said. "They help control the rodent population. There's reasons why it's good to have rattlesnakes around."
Reach Mark Muckenfuss at 951-368-9595 or mmuckenfuss@PE.com
SNAKE AID
If you have a snake problem on your property, call your local animal control:
Riverside County Animal Control: 888-636-7387
San Bernardino Animal Control: 800-472-5609
RELATED
Snake's venom felt in seconds
End
 | ||||||
