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.