The route of infection is best defined as:

• A. The manner in which a microorganism spreads from one individual to another
• B. The way a microorganism enters the body of a host
• C. How a disease progresses over time
• D. The way a host responds to a pathogen

Answer: (B)

The route of infection refers to the entry path a microorganism takes to enter the body's interior. It describes how a microbe gains access to the host, such as through inhalation into the lungs, ingestion into the gastrointestinal tract, or entry through broken skin or mucous membranes. This focuses on the portal of entry, not on how the microbe moves between people (that would be transmission), nor on how the disease develops over time (pathogenesis), or on how the host’s immune system responds. So the best way to define the route of infection is the method by which a microorganism enters the host’s body.