传染病是一类由致病微生物引起的,并可相互传播的疾病。目前发现传染病的种类正在不断发生转变,有的消灭了,有的死灰复燃,有的则是首次出现的。许多因素促成了传染病的发生和再发,其中较为关键的是人口高速增长、都市化、人类行为、贫困和气候环境状况恶化。 Infectious diseases are a group of diseases caused by pathogenic microorganisms that can spread to each other. It is now found that the types of infectious diseases are constantly changing, some eliminated, some resurgence, while others are the first to appear. Many factors have contributed to the occurrence and recurrence of infectious diseases. The more crucial ones are the rapid population growth, urbanization, human behavior, poverty and deteriorating conditions of climate and environment.