Environmental conditions, health behavior, and mortality in siblings as risk indicators of night blindness.

The purpose of the study was to estimate the association of environmental factors (water and sanitation), health behavior (breast feeding practice and vaccination), and mortality among siblings with night blindness. A total of 5,420 children were enrolled in a cross-sectional study from 2,101 households in the northern part of Bangladesh, a high risk area for night blindness. One hundred twenty-four children were reported by parents to have night blindness. Our results indicated that environmental factors, health behavior, and the death of siblings were significantly associated with the occurrence of night blindness in crude analyses, as well as in analyses with adjustment for a number of potential confounding variables. The strongest association was noted for sibling death. The findings support the notion that night blindness should not be viewed as an isolated health problem and that approaches aimed at improving vitamin A status should also include interventions directed to environmental and health-associated behavioral factors.