Foothill abortion disease.

Ranchers in California and neighboring states have struggled with foothill abortion disease at least as far back as the 1940s. While the disease seemed to have little impact on the health of the pregnant cows grazing in the foothills, it resulted in their calves being aborted, stillborn or born so weak that they soon died. After more than 50 years of research, the tick-borne bacterium responsible for one of the most troubling and economically devastating cattle diseases in the Western United States has been named and genetically characterized by researchers at the University of California, Davis. Veterinary immunologist Jeffrey Stott and collegues physically examined the bacterium in tissue sections taken during postmortem exams of aborted calves. They then characterized it by partially sequencing three of its genes and named it "Pajaroellobacter abortibovis," recognizing the Pajaroello tick that carries the bacterium as well as its abortion-inducing impact on infected cows and their fetuses. The researchers have developed a preventive vaccine for foothill abortion disease, and the Vaccine trials to prevent the disease are now in the second year. In the 1980s, UC Davis School of Veterinary Medicine researchers found evidence that the infected cow fetuses were producing an immune response to an unidentified microbe. Between 2000 and 2010, Stott and colleagues identified the microbe as a member of the genus Myxococcus and developed techniques to grow the live bacteria in laboratory mice. Cells from such mice were eventually used to develop the vaccine. This bacterium is like no other animal pathogen ever described,as It replicates only once per day, which explains why it could not be cultivated using standard laboratory techniques. The bacterium also has a much smaller genome than the most closely related, characterized bacterium, indicating that Pajaroellobacter abortibovis has probably lost some of its genetic material as it evolved. The Pajaroello tick is as intriguing as the disease-causing bacteria it carries, Stott said. Unlike more common ticks that burrow their way into the skin of people and animals to feed, the Pajaroello is a soft-bodied tick and does not embed itself in its hosts. The Pajaroello lives in the decomposing plant litter at the base of trees, shrubs and rocks, and is attracted to cattle by the carbon dioxide the animals give off. Only once every few months, the tick makes the effort to pierce the cow's skin and feed on its blood for about 20 minutes. When the bacteria get into the cow's tissue, they travel to the cow's uterus,in cows and other ruminants, no antibodies are passed between the mother and the fetus, so the fetus is immunologically naive and very vulnerable. The fetal development accompanied by a developed immune system triggers an immunological response to the presence of the bacteria. The fetus destroys itself and usually dies about four months after the cow is infected.. The economic losses recorded in cases of foothill abortion disease is high, the disease which occurs in California's coastal mountains and the foothill regions of California, Southern Oregon and Northern Nevada, annually results in the death of an estimated 45,000 to 90,000 unborn calves.