After wild pigs were linked to the deadly E. coli outbreak in California spinach nearly three years ago, Central Coast growers started shooting and poisoning wildlife.
Workers on one large farm killed 33 deer in a single year. Farmers poisoned ponds to get rid of frogs, ripped out trees and bushes and erected miles of expensive fencing.
But two years of testing wild animals and birds in the region suggests that only a small fraction actually carry the strain of Escherichia coli responsible for the contamination.
The results, released by the state Department of Fish and Game this week, "show that wildlife are not the Typhoid Marys some people think they are and some of the extreme measures are not necessary," said state wildlife biologist Terry Palmisano.
As part of an ongoing study of the pathogen, researchers collected samples from 866 animals, including 311 black-tailed deer, 184 feral pigs, 73 birds, 61 rabbits, 58 tule elk, squirrels, mice, skunks and coyotes.
Only four -- from a pig, a coyote and two elk -- tested positive for the lethal bacterium, E. coli 0157:H7. That is slightly less than half of 1%.
Three people, including a toddler, died in the spinach outbreak in the late summer of 2006. Federal authorities estimated that several thousand people were sickened across the country.
The contamination was traced to spinach grown on a cattle ranch east of Salinas. Although the precise source was never determined, the virulent E. coli was found in river water as well as in feces from cattle and wild pigs on the ranch.
The produce industry later adopted a voluntary set of standards for growing and handling leafy greens that amounted to a big "Keep Out" sign for any wildlife considered potential carriers of E. coli 0157:H7.
Big produce buyers also struck their own safety agreements with farmers, calling for even more precautions.
Requests jumped for state depredation permits allowing farmers to shoot wildlife damaging their crops. Growers who might otherwise have tolerated a deer browsing some lettuce shot the animals, fearing they couldn't sell a crop if safety auditors found droppings or tracks in a field.
"The buyers don't want even mice getting close," Palmisano said.
Baited PVC pipes with traps are a common sight along the edge of fields. Much of the Salinas River has been fenced. Grass along irrigation and runoff ditches has been dug up, leaving wide strips of bare ground.
