流行病学调查的目的主要是找出疾病发生的原因,以便有针对性地及早采取措施,制止疾病的蔓延和流行。但是,人们常常在疾病流行时或病人发生较多的时候才进行调查,而对散发病例不重视,即使调查也不及时。由此,造成病情扩大和蔓延。1 调查的重要性 所谓散发是指病例散在或零星地出现而言。任何传染病在人群中发生传播必须具备传染源、传播途径和易感者三个 The purpose of epidemiological investigations is mainly to find out the causes of the disease so that targeted and early measures can be taken to stop the spread and prevalence of the disease. However, surveys are often conducted at the time of the epidemic or at a time when the patient is experiencing a high incidence, with little regard for sporadic cases, even if the investigation is not timely. As a result, resulting in the expansion and spread of the disease. 1 The importance of the survey The so-called dissemination is the case of scattered or sporadic appearance. The transmission of any infectious disease in the population must have the source of infection, transmission and susceptibility of three