Rattlesnakes are biting people in record numbers throughout California, according to Stuart Heard, executive director of the California Poison Control System. And calls generated to the agency from Santa Clara County are five-fold this year, he said.
The agency has received 48 percent more calls this spring. From April through June, Poison Control received 184 calls compared to 114 for the same months in 2011, he said.
Most of the calls come from hospitals and medical centers in southern California, where many homes have been built in the mountainous canyons where the rattlers often live, he said.
But Santa Clara County has also seen an increase, he said. From April through June six bites were reported. Last year during the same period only one bite was reported in May, he said. In 2010 the agency received four calls from April through June, he said.
But those numbers only reflect the calls Poison Control received regarding questions about issues such as complex cases and antivenin doses. Heard said he believes the actual number of bites to be much greater.
Last year was a very wet winter that provided a good food source for the snakes, but this year's drier spring and summer might cause the snakes to seek food sources closer to people, he said.
Rattlers usually emerge from hibernation in April. They kill their prey and defend themselves by injecting venom into victims.
The poison can cause swelling, severe pain, blurring vision, vomiting, paralysis, sweating, breathing difficulty, low blood pressure, weak or rapid pulse, hemorrhaging, and in severe cases, death. Skin and muscles around the bite can "necrotize" or die, requiring weeks of hospitalization and surgery, according to the National Institutes of Health.
Rattlesnakes bite about six to 10 people in Santa Clara County each year, according to the Santa Clara County Emergency Medical Services Agency, which sent out a public-service warning in early June.
Northern Pacific rattlesnakes are northern California's only native species of venomous snake. The snakes are not aggressive. Most bites are the result of accidental contact or surprise.
"They would much rather be left alone, given the chance," said Robert Norris, M.D., a Stanford Hospital and Clinics wilderness medicine expert and chief of emergency medicine.
Few people die from the bites. Annually, there are about 8,000 venomous snakebites nationwide, resulting in only about six deaths, Norris said.
Rattlers are generally active April through September but will sometimes emerge from hibernating in places like rodent holes, crevices and rock piles on warm winter or late-autumn days to sun themselves, he said.
Rattlesnakes inhabit grasslands, the woods and hiking trails.
"Really, just about anywhere. I've seen some patients who were bitten in Palo Alto; one was in her garden when it happened," Norris said.
In the last 11 years only one rattlesnake has been seen in the Palo Alto Baylands, Supervising Ranger Rich Bicknell said. Rattlers are more common in Pearson-Arastradero Preserve and Foothills Park.
Usually the snake is spotted near a trail or in the brush nearby. The last time he recalled a rattlesnake bite in one of the city's open-space areas was when a dog was bitten five or six years ago, he said.
Although it is counterintuitive, the bigger the snake, the less likely a person is to die from a bite, he said.
"Adult snakes have more experience. A big snake knows it has to swallow whatever it wants to eat whole. Adult snakes have learned, 'I can't eat that person.' Often they will bite but not inject venom," he said.
Producing venom takes energy. A large snake knows it might need that venom to fight a raccoon or other predator or to kill its food. But a little snake will bite and inject all the venom at one time, he said.
About 25 percent of the bites are "dry," meaning no venom was injected, but the bites still require medical treatment, according to the California Department of Fish and Game.
Bicknell's advice for dealing with a snake is straightforward: "Don't play with it."
If it is close enough to poke with a stick, it is close enough to bite, he said. A rattler can strike the distance of its body length when coiled.
"And they spring fast," he said.
If a rattlesnake crosses one's path, Norris recommends giving it the right of way. If it's not moving, one can walk around it, making sure to stay at least several feet away, he said. Rattlers are not aggressive: If they feel threatened, they will generally try to slither away or give their infamous warning rattle -- although some may have lost or have not yet grown rattles.
Santa Clara County recommends the following to avoid a snakebite:
Give the snake plenty of room to get away.
Wear heavy boots that are four inches above the ankle and long pants when hiking.
Always watch where stepping and be sure to be look for snakes in areas of high brush, under logs and when stepping over logs, or fallen trees.
Be observant for snakes sunning on rocks or trails, especially in the cooler times of day.
Never try to touch a snake or scare it away. Give the snake its space and back away to a safe place.
Tell a ranger or park staff if you see a snake, and never try to catch it.
In the rare care case of being bitten by a snake:
Do not panic. Remain calm and slowly move away from the snake.
Call 9-1-1 or send someone for help.
Do not apply a cold pack, tourniquet, cut the bite, or attempt to suck out venom.
Avoid movement of the area that was bitten.
Keep the bite at or below heart level.
Do not attempt to kill or catch the snake, but do try to remember what the snake looked like.
If there is time, take note of the time of the bite.
Wait for help. Emergency medical personnel will get the bitten person to a place where they can receive antivenin to counteract the effects of the poison.