1. From Bangur Institute of Neurology (S.K.D., A.B., T.R., J.R.), Kolkata, India; National Neurosciences Centre (T.K.B., C.S.M.), Kolkata, India; All India Institute of Hygiene and Public Health (D.K.R.), Kolkata, India; Indian Statistical Institute (A.C.), Kolkata, India; and Institute of Post Graduate Medical Education and Research (A.H.), Kolkata, India.