Before It Causes Disease, a Pathogen Must First Cross

Question

Before it causes disease, a pathogen must first cross:
A) the lining of the stomach.
B) the blood-brain barrier.
C) from the blood into a cell.
D) an epithelium barrier.

Accepted Answer

Pathogens must first cross an epithelial barrier, which can be the skin or the lining of the gastrointestinal, respiratory, or urogenital tracts, to initiate infection. This is a critical step in the pathogenesis of many diseases.