Elizabethan England. Elizabethan people suffer from some afflictions that no longer exist in modern England. Plague is the obvious example but it is by no means the only one. Sweating sickness kills tens of thousands of people on its first appearance in 1485 and periodically thereafter. It is a terrifying disease because sufferers die within hours. It doesn't return after a particularly bad outbreak in 1556 but people do not know whether it has gone for good; they still fear it, and it continues to be part of the medical landscape for many years. How does the paragraph develop the central idea that Elizabethans suffered from diseases that are unfamiliar to modern readers

Everyone knows about the plague.

The paragraph turns its attention to sweating sickness that has two major outbreaks: 1485 and about 70 years later in 1556. It's a terrifying disease because it acts almost as quickly as a poison. The fact that it could come and go kept people on edge.

We moderns likely do not know what it is and what controls it. Certainly speaking personally, this the first time I've heard of it and maybe that's not a good yardstick. After running across 6000 questions, you might think it would have come up once.

The paragraph you quoted only records two instances. After that people just worried about it. Today only medical historians really know what it is.