An inflammation of the vein causes blood clots to form called

Phlebitis Definition. Phlebitis (fle-BYE-tis) is a condition in which a vein becomes inflamed (phleb=vein + it is=inflammation). The inflammation may cause pain and swelling. When the inflammation is caused by a blood clot or thrombus, it is called thrombophlebitis.

An epidemic is a large and localized outbreak of a sickness or disease.  a pandemic is a large global outbreak of a sickness or disease.