Borna disease virus infection in racing horses with behavioral and movement disorders

Borna disease virus (BDV) is a neurotropic agent with capacity to infect an d cause neurological disease in a broad range of warmblooded hosts includin g horses, sheep, cattle, cats, and possibly also humans. The epidemiology o f BDV is largely unknown. However, it is likely that subclinically infected animals may represent potential virus reservoirs. In two groups of Swedish racing horses, one clinically healthy and one consisting of horses with di ffuse neurological signs, the BDV seroprevalence was 24.5% and 57.7%, respe ctively. BDV RNA was detected in peripheral blood mononuclear cells in 8 ou t of 28 (28.6%) investigated horses, the majority of the BDV RNA-positive h orses belonging to the group with neurological signs. There was a close rel ationship between the Swedish equine BDV isolates and previously reported e quine BDVs in Europe. Our results point to an association of BDV infection with atypical disease patterns in horses such as diffuse mental and gait di sturbances. These findings may be of importance for the understanding of th e epidemiology of BDV infections in animals and man.