[The epidemiological survey as a key instrument for events of Public Health importance].

The epidemiological survey is one of the key instruments, both in Public Health alerts or emergencies, and in epidemiological surveillance. Its main objective is to obtain information quickly, systematically, uniformly and easily. It is characterized by being dynamic and flexible, in addition to offering the relevant descriptive information of the epidemiological event studied: person, place and time . Thus, it allows us to quantify the frequency and distribution pattern of the event through measures such as incidence, prevalence or mortality, providing the basic information to propose a starting hypothesis.