Could a virus cause Parkinson's disease?

(CNN) -- Michael J. Fox's new memoir hit the bookstores on Tuesday.

CNN NewsPass VIDEO CNN's Rhonda Rowland reports scientists want to know why four people -- including Michael J. Fox -- who worked together in Canada have developed Parkinson's disease. (April 2) Play video

In the book, he chronicles his entire life -- his childhood in western Canada, his television and film career and now his work as an advocate for Parkinson's disease awareness and research.

While Fox is promoting his book, a Canadian TV documentary that touches on his life is drawing attention. It claims that four people, including Fox, who worked together in Canada during the late 1970s have all contracted Parkinson's.

As CNN Medical Correspnondent Rhonda Rowland reports, the possible connection is raising questions.