Which viral infection always causes clinical disease in human beings-: (A) Rubella, (B) Poliomyelitis, (C) Measles, (D) Chicken pox
Answer is C. Rubella unfections are in fact subclinical.This represents the one of the major difference between measles and rubella(Ref.PARK'S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE 21st Edition page no.136)