What is a virus? 13 common viruses and the diseases they cause

Many of the viruses on this list are transmitted through droplets expelled when an infected person coughs or sneezes. — Photos: TNS

All of us are probably familiar with the word “virus”, but how many of us actually know what a virus is and how it acts?

A virus is an obligate intracellular parasite, which means that it can only reproduce inside a host cell, using the cell’s resources.