To borrow a term from my antivirus software, the body can "quarantine" infective agents,
preventing any symptoms, until many years later the quarantine barrier fails, and viable
pathogens are released. Even worse is tuberculosis. Patients with a healed "Ghon tubercle"
from adolescence, especially if weakened as by starvation, many ;years later may become
infectious again to children in their environment.That is why x-raying school teachers
protected many children.