What does the term 'carrier' refer to in the context of infectious diseases?

The term 'carrier' in the context of infectious diseases specifically refers to an individual who harbors a pathogen without exhibiting any symptoms of the disease. This means the person can still potentially transmit the infectious agent to others, even though they appear healthy themselves. Carriers play a crucial role in the epidemiology of infectious diseases, as they can contribute to the spread of infections without being detected due to the absence of visible symptoms.

In contrast, individuals showing symptoms of the disease are typically considered active cases rather than carriers, as their signs make the presence of the infection evident. Vaccinated individuals may have immunity and are less likely to become carriers, but the term 'carrier' is not applicable to them in this context. Finally, people who have recovered from a disease are often immune and do not carry the infectious agent in a transmissible form, making them distinct from carriers. Thus, the definition of a carrier focuses on the asymptomatic nature of the individual as it relates to infectious diseases.