Table 3.

Inclusion Criteria for Controls

1. Resides in demographic surveillance system area

2. Matched to the index case as follows:  • Age: ○ ±2 mo for cases 0–11 mo ○ ±4 mo for cases 12–59 mo ○ May not exceed the stratum boundaries of the case, eg, a control for an 11-mo-old case must be between the ages of 9 and 11 mo and a control for a 13-mo-old must be between the ages of 12 and 17 mo  • Same sex  • Residence: lives in the same or nearby village/neighborhood as the casea  • Time: enrolled within 14 d of presentation of the case

3. No diarrhea in the previous 7 db

^aEach site followed an algorithm beginning with the case's village/neighborhood, and then proceeding to villages/neighborhoods located at an increasing distance from the case's village/neighborhood until a control could be identified.

^bControl children will be included in the analysis irrespective of whether they developed diarrhea after enrollment.