Bartonella DNA more common in patients with psychosis

Research also identifies limitations with antibody testing.

NC State University doctor and researcher sits reading at her desk.

Researchers at North Carolina State University used DNA testing to show that Bartonella is more likely to be found in people with certain psychiatric disorders than in those without. Bartonella DNA was found in the blood of 43% of patients with psychosis compared to 14% in the control population.1

Bartonella are a group of vector-borne bacteria transmitted primarily via arthropods like fleas, lice and potentially ticks, but also by the animals that harbor them. For example, the species Bartonella henselae is associated with cat scratch disease, which until recently was thought to be a short-lived (or self-limiting) infection. There are at least 45 different known Bartonella species, of which 18 have been found to infect humans.2

The samples were provided by Dr. Shannon Delaney from Columbia University, where previous research showed that inflammatory markers are also elevated in patients with psychosis. Researchers from both universities agree that further research is required to understand these associations.

As an infectious disease researcher, I believe that infection should be critically examined as a potential cause of diseases for which the cause is unclear or unknown…Bartonella infection could be one possible candidate.

Dr. Edward Breitschwerdt

Another interesting finding in this research was that antibody testing for Bartonella was negative in some samples where Bartonella DNA were present, raising further questions about the sensitivity of antibody testing for these infections, and the overall rate of infection. All of these findings demonstrate an urgent need for further research regarding the association between infections such as Bartonella and mental health.


  1. Delaney S, Robveille C, Maggi RG, Lashnits E, Kingston E, Liedig C, Murray L, Fallon BA and Breitschwerdt EB (2024) Bartonella species bacteremia in association with adult psychosis. Front. Psychiatry 15:1388442. doi: 10.3389/fpsyt.2024.1388442
  2. Bartonella DNA Found in Blood of Patients With Psychosis,” retrieved June 8, 2024

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