Persistent (chronic) infection is defined as which?

• A. An infection with no active multiplication of the agent
• B. A chronic infection with continued low-grade survival and multiplication of the agent
• C. An infection that is always clinically evident
• D. An infection restricted to one organ system

Answer: (B)

Persistent infection means the pathogen is not cleared by the host and remains in the body for a long time, with the agent continuing to survive and multiply at low levels. This ongoing, low-grade replication keeps the infection alive over extended periods, sometimes with intermittent symptoms but often with little to no noticeable signs. This contrasts with latent infections, where replication is essentially paused for a time, and with infections that are fully cleared or rapidly resolved.

The description that best fits this idea is a chronic infection with continued low-grade survival and multiplication of the agent, because it captures the idea of ongoing presence and limited, persistent replication. The other statements don’t fit: no active multiplication describes a purely latent state, not persistence; infections that are always clinically evident are not a defining feature of persistence since many chronic infections can be asymptomatic; and being restricted to one organ system is about localization, not the persistence of the organism over time.