The promotion of proper infant feeding practices and the improvement of environmental sanitation have been two important strategies in the effort to reduce diarrhoeal morbidity among infants. Breast-feeding protects infants by decreasing their exposure to water- and foodborne pathogens and by improving their resistance to infection; good sanitation isolates faecal material from the human environment, reducing exposures to enteric pathogens. Taken together, breast-feeding and good sanitation form a set of sequential barriers that protect infants from diarrhoeal pathogens. As a result, breast-feeding may be most important if the sanitation barrier is not in place. This issue is explored using data from a prospective study of 2355 urban Filipino infants during the first 6 months of life. Longitudinal multivariate analyses are used to estimate the effects of full breast-feeding and mixed feeding on diarrhoeal disease at different levels of sanitation. Breast-feeding provides significant protection against diarrhoeal disease for infants in all environments. Administration of even small portions of contaminated water supplements to fully breast-fed infants nearly doubles their risk of diarrhoea. Mixed-fed and weaned infants consume much greater quantities of supplemental liquids, and as a result, the protective effect of full breast-feeding is greatest when drinking-water is contaminated. Similarly, full breast-feeding has stronger protective effects among infants living in crowded, highly contaminated settings.
PIP: Breast-feeding and good sanitation protect infants by decreasing their exposure to water- and foodborne diarrheal pathogens and by improving their resistance to infection. Using data from the Cebu Longitudinal Health and Nutrition Survey of 3080 children living in urban and rural areas of metropolitan Cebu city, Philippines, longitudinal multivariate analyses estimated the effects of full breast-feeding and mixed feeding on diarrheal disease at different levels of sanitation. 14 interviews of mothers were conducted during the third trimester of pregnancy, soon after birth, and every 2 months thereafter until the child was 2 years of age. The sample came from a 12-month cohort of all births in 17 randomly selected urban and periurban communities. Of the 2555 women recruited, 2355 had single, live births between April 1983 and May 1984. In urban Cebu, by 2 months of age 38% of the infants were mixed-fed, 19% were completely weaned, and 20% received nonnutritive liquids in addition to breast milk. The infants who were fully breast-fed dropped to fewer than 10% by the end of the first 6 months. During the first 6 months of life of the weaned children, breast-milk substitutes accounted for 88% of the total weight consumed at 2 months; 75% at 6 months. About half of the mixed-fed infants consumed breast-milk substitutes at 2 months of age. Approximately a quarter of those given the substitutes were exposed to milk products that had been stored without refrigeration for over an hour. By 4 months of age, semisolid foods were being given to almost half of the mixed-fed and weaned infants, and improper storage was common. In the multivariate model, both breast-feeding and environmental sanitation were important determinants of diarrheal disease during the first 6 months. The protective effect of full breast-feeding relative to no breast-feeding was large and statistically significant. Mixed-feeding had a somewhat smaller, yet statistically significant effect.