传染源、传播途径和易感人群是传染病发生和流行的三个基本环节，管理传染源、切断传播途径、保护易感人群，都可以有效地防止传染病的发生和流行。要实施上述三项措施，并发挥其最大效能和潜力，自然要求人们都能懂得这种措施的必要性和实施这种措施的的最佳时机及方法，... Sources of infection, routes of transmission, and susceptible populations are three basic links in the occurrence and prevalence of infectious diseases. Managing infectious sources, cutting off transmission routes, and protecting vulnerable populations can effectively prevent the occurrence and spread of infectious diseases. To implement the above three measures and to exert their maximum efficiency and potential, it naturally requires people to understand the necessity of such measures and the best time and method to implement such measures,...