A virus that infects animals but was thought to be relatively harmless to humans might contribute to some cases of mental illness, according to virologist Norbert Nowotny, of the University of Veterinary Sciences in Vienna. The Borna disease virus, which causes a fatal brain disease in animals, might be linked to schizophrenia, depression and chronic fatigue syndrome in humans.
The virus infects the nervous system tissue in horses and sheep, and triggers severe brain inflammation. The animals stop eating, become depressed and in almost all cases progress to paralysis and death within 3 weeks. There is no effective treatment.
These types of severe reactions do not occur in humans who become infected, Nowotny says. ?In humans, only subtle changes are suspected, which may interfere with neurotransmitter activities leading to psychiatric disorders.?
There is a variety of evidence from several research groups to support his theory. For example, antibodies to the virus have been found with higher frequency in the blood of people with diseases such as panic disorder than in those who don?t have this condition. Nowotny has isolated the virus?s genetic material from a man with chronic fatigue syndrome.
But other researchers have questioned the validity of his results, suggesting human samples may have been contaminated with virus from animals. Scientists can only make an educated guess that the virus is transmitted through the nasal passage, and it is not clear whether the virus passes from animals to humans or if there is a specific human strain.
Also, the disease occurs only sporadically, usually in a small region in central Europe. This suggests there is an animal reservoir, such as a type of rodent, but so far none has been identified.
?Currently, there are many open questions,? Nowotny says. ?If it is true, then it would be the first time that there is a virus involved in human psychological disease. If it is true that there is a human form of Borna disease, then I would expect that it would be a human virus transmitted from human to human. By learning more about how the virus is transmitted we can take actions to prevent it from causing disease in humans and animals.?
Watch out for Fido and Fluffy.
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