LONDON (Reuters Health) Jan 09 - Controversial evidence presented at a microbiology meeting here on Wednesday could, if confirmed, trigger another revolution in our understanding of mental illness.

Prof. Norbert Nowotny, from the University of Veterinary Sciences, Vienna, told researchers that Borna disease virus might be linked to schizophrenia, depression and chronic fatigue syndrome in humans.

In horses and sheep, the neurotropic virus triggers a severe meningoencephalitis. The animals stop eating, become depressed and in almost all cases progress to paralysis and death within 3 weeks. There is no effective treatment.

No such severe reactions are thought to occur in humans, Dr. Nowotny said at the meeting hosted by the European Societies of Clinical and Veterinary Virology and the Society for General Microbiology at the Royal College of Physicians in London. "In humans, only subtle changes are suspected, which may interfere with neurotransmitter activities leading to psychiatric disorders," he said.

A variety of evidence from several research groups supports the 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 controls. Dr. Nowotny's own lab has isolated the virus' genetic material from a man with chronic fatigue syndrome.

One lab in Japan has also reported finding higher incidence of antibody to the virus in people who work with horses.

But other researchers have questioned the validity of some results, suggesting samples may have been contaminated with virus from animals, leaving the scientific community split over whether the association is real.

Other unanswered questions include the epidemiology of the disease. Scientists only suspect 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 in a small endemic region in central Europe, which suggests there is an animal reservoir, such as a rodent, but so far none has been identified.

"Currently, there are many open questions," Dr. Nowotny acknowledged in an interview with Reuters Health. "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," he suggested. "By learning more about how the virus is transmitted we can take actions to prevent it from causing disease in humans and animals."

The next step in clarifying the issue is to conduct multi-centre trials that could rule out questionable results achieved in single labs, he said. Such trials are currently underway and publications should follow shortly.

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