How are host and parasite related?

Parasites are defined as organisms which live on or within some other living organisms deriving sustenance from it, the organism in which he lives is an host. A parasitic relationship is one in which one organism, the parasite, lives off of another organism, the host, harming it and possibly causing death.

Explanation:

answer; /// i believe that one of the causes is (a loss of habitat);

the roman republic began to expand when rome fought the punic wars and defeated carthage. the punic wars refer to the series of 3 wars fought among rome and carthage, before it ended in carthage's defeat.