In the study, infants born by C-section had fewer colonies of Escherichia and Shigella bacteria than those born vaginally.

CNN: Connection between dirty diapers, childhood health

For example, four different sorts of food-borne bug Salmonella, Shigella, Campylobacter and Yersinia can cause reactive arthritis, a painful inflammation of the joints that may last months or even years.

ECONOMIST: Bugged by disease

In adults, C. difficile infection is associated with diarrhea and unpleasant side effects, and while babies don't seem to be as affected by the bacteria, the presence of C. difficile could push out the Escherichia and Shigella that are so critical to developing a strong and healthy immune system.

CNN: Connection between dirty diapers, childhood health