> So what about Fox and the suspected Leo and Me cluster? Did they all breathe in some environmental toxin in the studio? Or did they perhaps pass the disease to each other? One theory, that has been around for years, is that Parkinson's could be caused - or perhaps triggered - by a viral infection, maybe even influenza.
> Dr Donald Calne, of the University of British Columbia Hospital, is treating two of the cast of Leo and Me. He told the Chicago Sun-Times that studies have found there to be an increased risk of clusters among certain workers who operate closely together - principally teachers, medical workers, loggers and miners. They could, the theory goes, be exposed to more viruses than most people, and this might cause them to develop the disease.