You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is In an epidemiological study, the first case whichcomes to the attention of the investigator is and explain in detail?
Index case Epidemiological terminology Primary case - is the _first case of a communicable disease introduced into the population unit under study. Index case - is the first case, that comes to the attention of the investigator, it is not always the primary case. Secondary cases - are those cases arising d/t contact with the primary case.