What kind of things might make a host susceptible to infection?

Answer 1

Infection is the detrimental colonization of a host organism by a foreign parasite species.

pathogenesis(why infection occurs)Persistent infection occur because the body is unable to clear the organism after the initial infection. Persistent infection are characterized by the continual presence of the infectious organism resulting in recurrent relapses.There are some viruses that can maintain a persistent infecting different cells of the body. A typical example is the herpes virus which tends to hide in nerves and become reactivated when specific circumstances arise.