What is a person called when they carry a pathogenic microorganism but do not show symptoms?

A person who carries a pathogenic microorganism without displaying any symptoms is referred to as a carrier. This term is significant in the context of infectious diseases because carriers can spread the microorganism to others, even though they themselves do not exhibit any signs of illness. The existence of carriers plays a crucial role in the transmission dynamics of many infectious diseases, as they can unknowingly pose a risk to others.

Contamination refers to the presence of unwanted substances in a sample or environment, but it does not specifically capture the nuanced role of an individual who is asymptomatic yet capable of spreading a pathogen. High risk generally describes individuals who are more likely to contract or be affected by a disease, rather than focusing on asymptomatic carriers. The term infectious implies the ability to transmit a disease, but it is broader and does not specifically denote individuals who are asymptomatic. Thus, the term carrier accurately encapsulates the situation being described in the question.