Bacteria from cat-scratch fever potentially linked to schizophrenia, UW-Madison study says

MADISON, Wis. -- Infection from bacteria associated with cat-scratch disease could potentially play a role in schizophrenia and schizoaffective disorder, according to a pilot study conducted in part by a UW-Madison veterinary medicine professor.

Researchers took blood samples from 17 people with medically managed schizophrenia or schizoaffective disorder and a control group of 13 healthy adults to test for evidence of Bartonella infection, which is associated with cats exposed to fleas and potentially ticks.

Of the 17 patients with schizophrenia, 12 had Bartonella DNA in their blood, compared to only one of 13 in the control group. Both groups reported similar pet ownership and flea exposures.

The study, published this month in the journal Vector-Borne and Zoonotic Diseases, was not able, by design, to show a causal link between Bartonella infection and schizophrenia. But researchers plan to do a larger study to see whether the preliminary results are borne out.

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Erin Lashnits, who recently joined the UW-Madison faculty, participated in the research while at North Carolina State University. Researchers have been looking at the connection between bacterial infection and neuropsychiatric disease for a while, with some studies suggesting cat ownership is associated with schizophrenia from a parasite that can cause toxoplasmosis, Lashnits said.

"So, we decided to look at another cat-transmitted infectious agent, Bartonella, to see if there could be a connection," she said in a statement.

Bartonella are bacteria historically associated with cat-scratch disease, also known as cat-scratch fever, which until recently was thought to be solely a short-lived, or self-limiting, infection. In people, the condition can include a bump or blister at the site of a cat scratch or bite, and lymph nodes may swell. People may also feel tired and have a headache or fever.

"While there is emerging understanding of neuropsychiatric illnesses such as schizophrenia as disorders of brain networks, the question about the actual causes remains unanswered," co-author Flavio Frohlich, associate professor of psychiatry at the UNC School of Medicine, said in a statement. "To our knowledge, this is the very first work that examines a potential role of Bartonella in schizophrenia."

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