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Fleas and CVBDs

DR. BREITSCHWERDT: We know that fleas carry several Bartonella species, and Wolbachia species has been amplified and sequenced out of fleas and dog blood. Fleas carry Bartonella species known to cause endocarditis in dogs and also in people, as well as other problems. So flea biology relative to the role of fleas in transmitting infectious agents is clearly more important than once thought only a few years ago.

DR. HOSTETLER: What is really going on out there related to Bartonella species infections in people and dogs?

DR. BREITSCHWERDT: In North America, Bartonella species infection was discovered as a cause of disease in people because of the HIV epidemic. From that very early association it became more obvious that Bartonella species was the cause of cat-scratch disease. If you read the older literature, about 10% of all people with cat-scratch disease had osteomyelitis, thrombocytopenia, and pleural and pericardial effusions, which were considered atypical manifestations of the disease. Those “atypical” manifestations are not so atypical and are due to persistent intravascular or intralymphatic infections with Bartonella species. There are a large number of papers finding Bartonella organisms in transplant patients and describing granulomatous hepatitis, granulomatous splenitis, and granulomatous lymphadenitis in children.

In our laboratory, we’ve developed a new way of growing Bartonella species out of the blood of dogs and people. Both can maintain a persistent Bartonella bacteremia for months to years. In a manuscript that was just accepted by the Journal of Clinical Microbiology, we present data suggesting that a mother transmitted this organism to two of her children; one is still infected 10 years later, the other died nine days after birth.5

DR. MATHER: Does the high incidence of immune suppression factor into that?

DR. BREITSCHWERDT: Yes, it’s an important factor of Bartonella infection that’s been demonstrated both in veterinary and human medicine. The very first Bartonella organism isolated from a dog would have never occurred if it were not for the fact that the veterinarian was immunosuppressing the dog and treating it for lupus.

We’ve seen subsequent examples of veterinarians treating immune-mediated thrombocytopenia, immune-mediated polyarthritis, or immune-mediated meningoencephalitis in which we were able to detect Bartonella species in blood samples by using PCR, but still couldn’t grow it without completely changing our approach. Endocarditis is probably the best example. Immunosuppression likely raises the level of bacteremia and allows the organism to localize to the heart valve.