Subclinical BDV infections have been shown to predominate in horses, with the only symptoms being attacks of colic. A number of researchers have posited an infectious etiology for human affective disorders. Descriptive epidemiologic studies have shown that schizophrenia is unequally distributed in time and place. More recently, a case control study supported the association of cat ownership with schizophrenia. These findings have demonstrated a wide geographic distribution of BDV, with studies conducted in Central Europe, North America, East Africa and Japan.
Most viruses demonstrate organ specificity, including nervous tissue.
The rabies virus is an example of a zoonotic neurotropic viral agent, transmitted by saliva and spread intra-axonally to the central nervous system causing a fatal encephalitis. The rabies reservoir includes a wide variety of mammals which, upon occasion, include humans. Independent of present day serosurveys and limited intervention studies, to hypothesize that a virion such as BDV causes lingering, subacute central nervous dysfunction, is not implausible or irresponsible. Morse SS, Emerging Viruses, Oxford University Press, New York, 1993.