Researchers at the UC Davis School of Veterinary Medicine are working to develop a vaccine to prevent a bacterial disease that annually causes the loss of 45,000 to 90,000 calves, costing $6.3 million to California cattle producers.

Foothill abortion, a bacterial disease also known as epizootic bovine abortion, is transmitted by bites from the pajaroello tick. This tick lives in the soil around trees, in dry brush areas and around rock outcroppings of foothill rangelands. Although infected pregnant cows show no obvious clinical symptoms, they will abort their calves anywhere between six to nine months into the pregnancy. (The gestation period for a cow is nine months, the same as for humans.) Some infected cows will carry the pregnancy to term, but their calves are born weak and fail to thrive.

Research has identified a particular bacterium, never before described, as the cause of foothill abortion. Progress on developing a vaccine has been slow due to the inability to culture the bacteria in the laboratory; however, researchers are currently using molecular approaches to begin characterizing this unique bacterium.

"There is evidence that the infected cows and their fetuses are producing an immune response to the bacterium," said Jeffrey Stott, a veterinary pathologist who is leading the effort to develop a vaccine for foothill abortion. "This is encouraging because it indicates that a properly formulated vaccine should be effective in preventing this disease."

The School of Veterinary Medicine recently received a $50,000 contribution from the California Cattlemen's Association to support research focused on developing a vaccine for foothill abortion.

Stott and colleagues are hopeful that an experimental protein-based vaccine can be developed and might be available for immunizing heifers and cows in about three years.