Which statement is true about the chain of infection?

Which statement is true about the chain of infection?

• A. All links must be present for infection to spread
• B. Infection can occur with only the agent present
• C. The portal of exit is optional
• D. The reservoir is always essential

Answer: (A)

The key idea is that infection spreads only when every link in the chain is present and capable of functioning. The chain of infection includes six elements: the infectious agent, a reservoir where the agent lives, a portal of exit for the agent to leave the reservoir, a means of transmission, a portal of entry to a new host, and a susceptible person. If any one of these links is missing or blocked, transmission cannot occur. That’s why the statement that all links must be present is true—the spread of infection depends on the complete chain being intact. For example, without a susceptible host or without a transmission route, the agent cannot move from one person to another, even if the agent is present. Likewise, blocking the portal of exit or the transmission pathway interrupts spread. The other options fail because they imply that infection can occur with incomplete linkage or minimize one necessary component, which the chain-of-infection model does not support.

The key idea is that infection spreads only when every link in the chain is present and capable of functioning. The chain of infection includes six elements: the infectious agent, a reservoir where the agent lives, a portal of exit for the agent to leave the reservoir, a means of transmission, a portal of entry to a new host, and a susceptible person. If any one of these links is missing or blocked, transmission cannot occur. That’s why the statement that all links must be present is true—the spread of infection depends on the complete chain being intact.

For example, without a susceptible host or without a transmission route, the agent cannot move from one person to another, even if the agent is present. Likewise, blocking the portal of exit or the transmission pathway interrupts spread. The other options fail because they imply that infection can occur with incomplete linkage or minimize one necessary component, which the chain-of-infection model does not support.