1. From the Division of Epidemiology and Community Health (K.L., R.V.L.) and the Department of Neurology (K.L., G.V., D.C.A.), University of Minnesota, Minneapolis, Minn; the Minnesota Department of Health (A.W.T., J.M.P.), St. Paul, Minn; and the Centers for Disease Control and Prevention (X.T., M.G.G.), Atlanta, Ga.