Diarrhea is the 2nd most common cause of child deaths worldwide. In fact, diarrhea is the cause of 4% of all deaths worldwide and that adds up to around 2.2 million people each year (according to the WHO).
When you see a large crack in the wall, you have to be careful because you never know if the crack has gone down to the foundation. When impoverished people get diarrhea, it could just be a week long, surface level sickness, or it could have tapped into their foundation and be the thing that kills them.
Diarrhea is 100% preventable.