Diets of excessive protein, improper food combinations, or just overfeeding are known causes diarrhea. Infants that are fed inappropriate diets that include meat, dairy, refined sugar, or even chilled or heated fruits or vegetables, render their intestines an ecological mess. Even on a proper diet, it may take an extended period of time for the restoration of normal intestinal flora that is essential to process waste in the colon. But when anti-diarrhea medications of any type are added to the mix, the infant is rendered incapable of fully restoring that normal bacterial balance. That, together with malnutrition, accounts for the higher mortality rates there.
Diarrhea is also often a symptom of allergies.
If you really want to get holistic, consider the increasing rate of allergic children as one cause of the increased prevalence of diarrhea. But it's not profitable for any drug company to investigate such potential causes of diarrhea. Symptoms of this problem includes diarrhea, abdominal pain, intestinal bloating and possibly food intolerance. According to Dr. Wakefield, et.al., there is strong evidence linking the administration of MMR vaccine with the development of leaky gut, as well as Crohn's disease, non-specific colitis, and other digestive problems. But any sane parent would reject both.