The complementary effect of latrines and increased water usage on the growth of infants in rural Lesotho.

The effects of water quantity and sanitation, alone and in combination with each other, on infant weight gain and length gain were examined. Data on 119 infants were collected from 20 villages in rural Lesotho between July 1984 and January 1985. The interactions between sanitation and increased water usage for weight gain (p = 0.007) and length gain (p = 0.006) were significant after potential confounding was controlled. The biggest growth effects were dependent on families possessing a latrine and increasing their use of water during the warm, wet season. Infants gained 1.031 kg (95% confidence interval (CI) 0.420 to 1.642) and 2.028 cm (95% CI 0.523 to 3.533) more when both positive factors were present, as compared with only having a latrine. Increasing water usage compared with not increasing water usage resulted in only 0.105 kg (95% CI -0.175 to 0.385) more weight gain and -0.309 cm (95% CI -1.005 to 0.387) more length in the absence of a latrine. Similarly, infants gained 1.106 kg (95% CI 0.484 to 1.728) and 2.076 cm (95% CI 0.559 to 3.593) more if both factors were operating than did infants whose families only increased their water usage. In the nonincreased water group, the difference in growth between having and not having a latrine was 0.180 kg (95% CI -0.093 to 0.453) and -0.261 cm (95% CI -0.951 to 0.429). Water supply programs should emphasize use of more water for personal hygiene, and sanitation programs should install toilet facilities where water usage is high or has been increased because of an educational program.