1　导言流行这一词起源于希腊文到来或停滞在一个地方 ,从原则上讲 ,任何疾病发病率突然增加 ,都需考虑这已构成流行。流行发生的基本必要条件是存在大量易感性人群 ,实际上 ,流行不仅仅是发病率的增加 ,也影响到一般人群的健康。很多疟疾的流行是与饥荒、经济危机、战争、穷困 1 Introduction The term prevalence originated in the Greek language or stagnated in one place, in principle, the sudden increase in the incidence of any disease, have to consider that this has become popular. The basic prerequisite for the occurrence of the epidemic is the existence of a large number of susceptible populations, in fact, the prevalence is not only an increase in the incidence, but also affect the general population health. The prevalence of many malaria is associated with famine, economic crisis, war, poverty