New bacterium related to cat scratch fever isolated at UCSF

A close cousin of the potentially fatal bacterium that debilitated hundreds of AIDS patients in the late 80s has been isolated at the University of California at San Francisco, reported a press release from the UCSF News Office. The bacterium was found in a woman who had been on an international vacation. Although she has since recovered, she suffered potentially life-threatening anemia, a rash, an enlarged spleen, insomnia, and a high fever that lasted for several weeks.

At first she was diagnosed with malaria or typhoid fever, two infections that commonly occur in returning travelers. But further genetic work revealed that the woman, who had traveled in the Peruvian Andes, was infected with a new bacterium that had never been discovered in a human being.

The new species, named Bartonella rochalimae, is closely related to one spread by body lice in the trenches during World War I, commonly called trench fever. It is also similar to a bacterium identified approximately 10 years ago as the cause of cat scratch disease, Bartonella henselae, which infects more than 25,000 people a year in the United States.

The discovery is reported in the June 7 issue of The New England Journal of Medicine.

Prior to 1990 no Bartonella infections had been isolated in the U.S. The new discovery is the sixth species identified that can infect humans, said Dr. Jane Koehler, professor of infectious diseases at UCSF, in the press release.

Koehler encountered her first patient infected with Bartonella in 1987 at the AIDS Clinic at San Francisco General Hospital Medical Center.

“The bacteria were eating away a bone in the arm of an AIDS patient—for months,” Koehler recalls in the press release. “They can cause extremely painful lesions and tumors of blood vessels on the skin of immunocompromised patients. But when I saw this patient, this type of infection had never been seen at UCSF, and the bacterium causing the infection was unknown."

Koehler’s group went on to discover that two different Bartonella species—one related to trench fever and one related to cat scratch disease—can cause these disfiguring and potentially fatal infections in AIDS patients.

Caregivers and medical staff need to know about the different species so AIDS patients are cautioned about the dangers of cat scratches and exposure to body lice, Koehler explained in the press release. Medical staff should know to look for Bartonella infections if someone with a persistent, unexplained high fever has a cat, has been homeless or has been in the Andes Mountains.

“As we continue to discover new pathogens and how humans get infected with them, we improve our ability to diagnose, prevent and treat our patients,” Koehler notes in the press release. “This enables us to use our work in the laboratory to benefit patients in the clinics and hospital.” (The Advocate)