People cannot get Borna virus from eating meat or other products of infected animals, Bode said. Not all infected animals show symptoms. But horses can go through episodes of apathy, energy loss and sleepiness before reaching a complete remission, she said. Traces of Borna virus are found in a part of the horse brain that controls emotion, suggesting the behavior comes from interference there rather than a general reaction to feeling ill, she said. Infected cats can stagger and also act depressed and apathetic, Bode said.
Cats can also recover on their own.
No antiviral treatment has been found. Prior evidence of human infection has included detection of immune system proteins that appear to signal exposure to the virus, and the finding of proteins and genetic material that appear to be from Borna virus. Bode and colleagues have found that the viral proteins and genetic material tend to appear during or near episodes of depression, suggesting that the virus can promote depression when it is activated from a dormant state. But scientists suspect infection causes no problem in most people, she said. Instead, it may bring on depressive episodes in people predisposed by their genes or other factors, maybe by disrupting communication between brain cells, she said.