Which effect of the plague does the narrator in "The Decameron" describe as "even worse, and almost incredible" as he tries to convey the horror of that time period?

The effect of the plague that the narrator in "The Decameron" describes as "even worse, and almost incredible" as he tries to convey the horror of that time period is: Parents refused to care for their dying children.

Fathers and mothers refused to assist and care for their own children, it was as if their children did not belong to them.

The quote of this section of The Decameron reads:

"but even worse, and almost incredible, was the fact that fathers and mothers refused to nurse and assist their own children, as though they did not belong to them."

Therefore, what Bocaccio is shocked by is the fact that mothers and fathers did not take care of their own children. He tells us that they were too scared of the disease, and often left them to die. This is an example of the deep fear and shock that people experienced due to the plague, and the huge impact that it had on the population.