system
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.
user
In epidemic, 1st step is -
assistant
The correct answer is  Investigation of an epidemic: Verification of diagnosis Confirmation of the existence of an epidemic Defining the population at risk Rapid search for all cases and their characteristics Data analysis Formulation of hypothesis Testing of hypothesis Evaluation of ecological factor Fuher investigation of population at risk Writing the repo Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 143