Schizophrenia and Bartonella spp. infection: A pilot case–control study

Recently, infections with emerging zoonotic bacteria of the genus
Bartonella have been reported in association with a range of CNS symptoms.
Currently, it remains unknown if Bartonella spp. infection is
associated with symptoms of schizophrenia/schizoaffective
disorder (SCZ/SAD). The objective of this study was to determine
if there is an association between Bartonella species infection and
SCZ/SAD. A secondary objective was to determine if SCZ/SAD
symptoms were more severe among participants with documented
Bartonella spp. infection. Using a case–control study design, 17
cases and 13 controls were evaluated with a series of clinical
and cognitive assessments. Blood samples were collected and tested for
Bartonella spp. infection using serological, microbiological, and
molecular techniques. People with SCZ/SAD were more likely than
healthy volunteers to have Bartonella spp. DNA in their
bloodstream, with 11 of 17 cases (65%) positive by
Bartonella spp. droplet digital PCR (ddPCR). In comparison, only
one healthy volunteer was Bartonella spp. ddPCR positive (8%, p =
0.0024). Based on serology, Bartonella spp. exposure was common among
people with SCZ/SAD (12 of 17) as well as among healthy
volunteers (12 of 13), with no significant difference between
the groups ( p = 0.196). Within the case group of people with
SCZ/SAD, there was no significant difference in SCZ/SAD severity
scores between people with and without ddPCR evidence of Bartonella spp.
infection. This pilot study provides preliminary evidence in
support of future investigations that should examine a
potential contribution of Bartonella spp. infection to SCZ/SAD.