Self-reported diarrhea in a control group: a strong association with reporting of low-pressure events in tap water.

In a recently conducted case-control study of sporadic cryptosporidiosis, 6.6% of subjects in the control group reported having had diarrhea in the 2 weeks before completion of the questionnaire. In an analysis of this control group, there was a very strong association between self-reported diarrhea and reported low water pressure at the faucet.