This individual is a healthy carrier.
A healthy carrier (sometimes called asymptomatic carrier) refers to a person whose organism is infected by a microorganism (virus, bacteria, parasite) without presenting any clinical manifestation.
This absence of reaction may result either from a weakness of the infectious agent or from the effectiveness of the defenses of the subject.
Nevertheless, a healthy carrier can transmit a disease to other people. This is for example the case of hemophilia or certain genetic pathologies.