Parkinson's disease is a neurogenerative disease that affects more than 1 million people in the U.S. While some cases are caused by genetics, the cause is unknown in most.

A progressive neurological disorder affecting 10 million people globally, Parkinson’s can cause disruptive symptoms such as tremors, immobility and loss of balance. Now, scientists at Northwestern Medicine have discovered that a usually harmless virus — the Human Pegivirus — may be a contributor to the disease.