ALL COLIFORMS ARE NOT CREATED EQUAL - A COMPARISON OF THE EFFECTS OF WATER SOURCE AND IN-HOUSE WATER CONTAMINATION ON INFANTILE DIARRHEAL DISEASE

Storing drinking water in the home is common in the developing world. Several studies have documented increased concentrations of fecal coli forms during household storage. This has led to the belief that in-hou se water contamination is an important transmission route for enteric pathogens and, moreover, that improving water source quality is not wa rranted until that quality can be maintained in the home. We contend t hat in-house water contamination does not pose a serious risk of diarr hea because family members would likely develop some level of immunity to pathogens commonly encountered in the household environment. Even when there is no such immunity, transmission of these pathogens via st ored water may be inefficient relative to other household transmission routes, such as person-to-person contact or food contamination. A con taminated water source poses much more of a risk since it may introduc e new pathogens into the household. The effects of water source and in -house contamination on diarrheal disease are estimated for 2355 Filip ino infants. The results confirm our hypothesis: contaminated water so urces pose a serious risk of diarrhea while contamination of drinking water in the home does not. Water boiling is shown to eliminate the ri sk of diarrhea due to water source contamination. The results imply th at improvements in water source quality are more important than improv ing water storage practices.