Q. In the cases you described, is there evidence that treating with antibiotics improved any of the nonspecific symptoms in the affected people?
A. An authoritative review in the human literature published two or three years ago on how to treat Bartonella species infection in people focuses on treating cat scratch disease, which generally isn't treated with antibiotics because no antibiotic, including azithromycin, has made a difference in patients with cat scratch disease. I do not think we know how to treat chronically Bartonella-infected immunocompetent people yet. Some patients who receive antibiotics show improvement in clinical signs and later have undetectable antibodies and organism DNA, whereas other patients do not improve with antibiotic therapy.
Q. Physicians would be excited about having a test to detect acute or chronic bartonellosis. But in your studies, why are the numbers small and lacking controls?
A. We have done a controlled study with the Duke University Medical Center that we hope will be finished soon. And this study involved ill veterinarians and healthy veterinarians who provided blood samples at a national veterinary meeting, plus a cohort of people with minimal exposure to animals and arthropods as a control population. My frustration is that I believe there is a potential for a hidden epidemic, yet there is only one NIH-funded study regarding Bartonella species in this country. It's difficult to do good science without funding.
Q. Can you comment on the relationship of Bartonella species infections to uveitis in cats? It's a hot topic in veterinary ophthalmology because Bartonella species are found in a large percentage of cats.
A. We've cultured and PCR-confirmed B. henselae in the aqueous humor of cats, but I doubt it's there because it is the primary pathogen in cats with uveitis.
Q. Is there any evidence of head lice becoming Bartonella species vectors for kids?
A. To my knowledge, no data suggest that Bartonella species transmission has occurred via head lice. In a study from San Francisco last year, 33% of body lice and 25% of head lice were found to contain B. quintana DNA.1 But as in ticks, finding organism DNA in a potential arthropod vector doesn't mean the parasite is vector competent.
1. Bonilla DL, Kabeya H, Henn J, et al. Bartonella quintana in body lice and head lice from homeless persons, San Francisco, California, USA. Emerg Infect Dis 2009;15(6):912-915.