What is likely the cause of young Kristoforas' death? What message is Sinclair communicating through this incident?

That spring, little Kristoforas dies. He is killed by a tubercular sausage. An hour after eating the sausage, he begins crying in pain and dies before a doctor can reach him. Even children can't get basic nutrition. Sinclair is saying that children, the most vulnerable in society that should be protected, suffer at the hands of the Capitalist system.