What is the first case of a paicular condition that comes to notice of a physician termed as?

Index case is the first case that comes to the attention of the investigator. Case is defined as a person in the population or study group identified as having the paicular disease, health disorder or condition under investigation. - Primary case: It is the first case of a communicable disease introduced into the population unit being studied. - Secondary case: are those developing from contact with a primary case.