<prompt> Index case refers toFirst case of a communicable disease introduced into the population unit being studiedFirst case to come to attention of investigatorDeveloping from contact with primary caseAn individual who has signs and symptoms connected to the suspected pathogens  <response>: First case of a communicable disease introduced into the population unit being studied Primary case First case to come to attention of investigator Index case Developing from contact with primary case Secondary case An individual who has signs and symptoms connected to the suspected pathogens Suspect case 