So WE are a sickness, a disease. That’s what he’s saying.
Jmo, a close allegory to what the nazi's thought of Jews.
“He was the commander of a vast shadowy army, un underground network of conspirators dedicated to the overthrow of the State.
– George Orwell, 1984. Part 1, Chapter 1.
This refers to Emmanuel Goldstein, a scapegoat for the Thought Police and the principal enemy of the Party.