Ticks collected in Santa Clara County, California, carried Bartonella bacteria that infect cats, dogs, cattle and sometimes humans, according to a new study. Bartonella henselae, the agent of "cat scratch" disease, usually causes a mild fever in humans but can be serious or fatal in patients with a weakened immune system.
"At the least we can say that ticks carry Bartonella DNA and could be potential vectors," said Bruno Chomel, professor of veterinary medicine at the University of California, Davis, and one of the authors of the study.
Chomel and graduate student Chao-Chin Chang, working with colleagues from the Santa Clara County Department of Health Services, collected ticks and tested them for Bartonella DNA. Almost 20 percent of the ticks collected were infected with Bartonella species found in cats, dogs, cattle and other animals.
Although there is no clear evidence that humans can develop the disease from tick bites, there were some reported cases of cat scratch disease where the only risk factor was a tick bite, said Chomel.
More research is needed to find out the role of ticks and other animals in transmitting these bacteria between animals and to humans, Chomel said.
The study is published in the April issue of the Journal of Clinical Microbiology.