Throughout the long history of human coexistence with microorganisms, infectious diseases have consistently been a major challenge to public health. Whether it's influenza viruses, rotaviruses, or the novel coronavirus, these tiny pathogens spread through multiple routes, including droplets, contact, air, and the digestive tract, posing a threat to our health and society. Understanding infectious diseases hinges on mastering three key elements: the source of infection (a person or animal carrying the pathogen), the transmission route (how the pathogen leaves the source of infection and reaches healthy individuals), and susceptible populations. Public health measures, such as vaccination, wearing masks, frequent handwashing, and maintaining social distancing, effectively control the spread and prevalence of diseases by breaking one or more of these links. Popularizing this knowledge is the cornerstone of building a social health defense line. Our interactive exhibit on "Common Infectio
