A question that has been simmering for years in the veterinarian community is now attracting the interest of physicians as well: Do the bacteria that cause cat scratch disease—a typically mild illness with flulike symptoms—also cause chronic fatigue syndrome? Decades of case reports hint at associations between fatigue, chronic headaches, numbness, pain and cognitive impairment and infection with Bartonella. Yet researchers still do not have clear answers.

Recent research found fragments of Bartonella species' DNA in 41 percent of 296 patients examined by a rheumatologist. Many of them had visited multiple specialists without finding relief from their symptoms. The findings, published in May 2012 in Emerging Infectious Diseases, drew criticism in two letters to the editor, published last November, which expressed concerns with patient inclusion criteria and a low threshold cited as evidence of infection. “We must be cautious before attributing illnesses X, Y and Z to Bartonella infection without solid evidence,” says Christina Nelson, a medical epidemiologist at the U.S. Centers for Disease Control and Prevention, who adds that the study results were difficult to interpret.

Complicating matters is the pathogen's elusive biology: it evades detection within hosts by changing proteins on its surface and by hiding inside blood vessels. In addition, the organism can shift strategies depending on whether it is in a mammalian host, such as a cat or dog, or an insect vector, such as a flea or tick. “We are not even at the tip of the iceberg” when it comes to understanding Bartonella, says Jane Koehler, a professor of medicine at the University of California, San Francisco.

This article was originally published with the title Stealth Pathogen.

3 Comments

1. 1. cfsboston 10:28 PM 12/31/12

   Chapter 33 of Hillary Johnson's: Osler's Web: Inside the Labyrinth of the Chronic Fatigue Syndrome (CFS) Epidemic is entitled "HIV-NEGATIVE AIDS."
   
   Neenyah Ostrom's book "America's Biggest Cover-up: 50 More Things...CFS and Its Link To AIDS" cites as # 1 thing: "Some CFS Patients May Be Non-HIV AIDS Cases."
   
   NON HIV AIDS cases, ICD-coded "CFS," are cited in medical journals since 1992.
   
   Will CFS ever make any progress unless we acknowledge this fact?
   
   UK PROGRESSIVE recently published one of my letters about my life with NON HIV AIDS. This is its 9th publication on 4 continents -->
   
   http://ukprogressive.co.uk/the-aids-like-disease-seldom-mentioned/article20891.html
   
   or just google "non hiv aids"

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2. 2. denswei 01:05 PM 1/5/13

   Interesting parallels with Lymes disease…..

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3. 3. Laroquod 12:59 PM 1/6/13

   This just in! Scientists know nothing about this particular issue. When asked by reporters, they repeatedly stated that they can make no conclusions. More news on this highly important and completely unsurprising lack of knowledge is coming in our 10-page feature report. You read it here on *Scientific American*.

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