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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
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Which viral infection always causes clinical disease in human beings-
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The correct answer is  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)