Contagion

Roles: pathogen, host, carrier, vector, transmission, infection, epidemic, containment, quarantine, inoculation, immunity, herd-immunity, outbreak, virulence

The population-level spread of disease through transmission from host to host. Where the medicine frame centers on the clinical dyad (healer treats patient), contagion centers on epidemiological dynamics: how pathogens move through populations via vectors and carriers, how outbreaks escalate into epidemics, and how collective measures (quarantine, inoculation, herd immunity) contain them. As a source domain, contagion is especially productive for phenomena that spread person-to-person without full awareness — ideas, emotions, behaviors, financial panics — because it foregrounds involuntary transmission, exponential growth, and the tension between individual exposure and population-level intervention.

As Source Frame (3)

• Computer Virus Is Biological Infection → network-security
• Dangerous Beliefs Are Contagious Diseases → mental-experience
• Failure Isolation Is Quarantine → software-engineering, systems-thinking