Breastfeeding and the Risk of Life-threatening Enterotoxigenic Escherichia coli Diarrhea in Bangladeshi Infants and Children John D. Clemens, MD*‡; Malla R. Rao, MPH*‡; J. Chakraborty*; Mohammed Yunus, MD, MSc*; Mohammed Ali, MSc*; Bradford Kay, DrPH*; Frederick P. L. van Loon, MD, MPH*; Abdullah Naficy, MD, MPH‡; and David A. Sack, MPH*§ ABSTRACT. Objective. To assess the relationship be- tween breastfeeding and the risk of life-threatening en- terotoxigenic Escherichia coli (ETEC) diarrhea among Bangladeshi infants and young children <36 months of age. Design. Case– control study. Setting. A rural Bangladesh community. Participants. A total of 168 cases with clinically se- vere ETEC diarrhea detected in a treatment center-based surveillance system during 1985 to 1986 and 3679 controls selected in three surveys of the same community during the same calendar interval. Outcomes. Cases and controls were compared for the frequency of antecedent breastfeeding patterns. Results. Compared with other feeding modes, exclu- sive breastfeeding of infants was associated with signif- icant protection against severe ETEC diarrhea (relative risk [RR]  0.51; 95% confidence interval [CI]: 0.28,0.96). However, during the second and third years of life, the risk of this outcome was similar in both breastfed and nonbreastfed children (RR  0.98; 95% CI: 0.45,2.12), and no significant overall protective association between breastfeeding and severe ETEC diarrhea was evident during the first 3 years of life (RR  0.86; 95% CI: 0.43,1.74). Conclusions. Exclusive breastfeeding appeared to protect infants against severe ETEC diarrhea, but breast- feeding was not associated with protection after infancy, nor was it associated with a major overall reduction of severe ETEC disease during the first 3 years of life. Al- though not diminishing the importance of breastfeeding, our findings suggest that other interventions, such as immunization and education about proper food hygiene, may also be required in efforts to prevent this major pediatric disease. Pediatrics 1997;100(6). URL: http:// www.pediatrics.org/cgi/content/full/100/6/e2; enterotoxi- genic Escherichia coli, breastfeeding, diarrhea. ABBREVIATIONS. ETEC, enterotoxigenic Escherichia coli; LT, heat labile toxin; ST, heat stable toxin; RR, relative risk; CI, confidence interval. E nterotoxigenic Escherichia coli (ETEC) is a major infectious etiology of pediatric diarrhea in de- veloping countries and a significant cause of death in these settings. 1,2 Despite the potential effec- tiveness of case management of ETEC diarrhea with suitable rehydration therapy, many children in de- veloping countries fail to receive adequate rehydra- tion for diarrheal illnesses, 3 and even appropriate rehydration will not necessarily prevent the nutri- tional faltering that has been associated with ETEC diarrhea. 4 For these reasons, interventions to prevent ETEC diarrhea are needed. Promotion of breastfeeding has been accorded an important role in primary health care programs in developing countries. 5 Several indirect lines of evi- dence suggest that breastfeeding may protect infants and young children against ETEC diarrhea. Ingestion of hyperimmune colostrum has been shown to pro- tect suckling newborn animals against natural ETEC infections. 6 Moreover, oral administration of hyper- immune colostrum to adult human volunteers pro- tected them against an experimental ETEC infectious challenge. 7 However, surveillance data from devel- oping countries have often revealed an appreciable incidence of ETEC diarrhea during infancy, 8 when breastfeeding is common, questioning whether breastfeeding is actually associated with a lower risk of ETEC diarrhea in these settings. In this paper, we report a case– control study of the association between breastfeeding and the risk of severe ETEC diarrhea in rural Bangladeshi infants and young children. We chose severely dehydrating ETEC diarrhea as the study endpoint, because this outcome is of clear public health importance. More- over, we selected rural Bangladesh as the setting for addressing this issue, because breastfeeding has been shown to be related protectively to several enteric infections in this setting. 9 –11 METHODS Setting for the Study The study was conducted in the Matlab field studies area of the International Centre for Diarrhoeal Disease Research, Bangladesh, a rural area with approximately 200 000 residents. In conjunction with a field trial of oral cholera vaccines initiated in 1985, 12 sur- veillance was instituted for all patients seeking care for diarrhea at the three Matlab diarrheal treatment centers. In this surveillance, patients received systematic clinical and microbiological assess- ments, and selected dietary and sociodemographic information was collected. Fecal specimens were evaluated for ETEC by testing five lactose-fermenting colonies for heat labile (LT) and heat stable From the *International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh; ‡National Institute of Child Health and Human Development, Bethesda, Maryland; §Johns Hopkins School of Public Health, Baltimore, Maryland; and Centers for Disease Control and Prevention, Atlanta, Georgia. Received for publication Oct 3, 1996; accepted Jul 7, 1997. Reprint requests to (J.D.C.) Division of Epidemiology, Statistics, and Pre- vention Research, National Institute of Child Health and Human Develop- ment, 6100 Executive Blvd, Bethesda, MD 20892-7510. PEDIATRICS (ISSN 0031 4005). Copyright © 1997 by the American Acad- emy of Pediatrics. http://www.pediatrics.org/cgi/content/full/100/6/e2 PEDIATRICS Vol. 100 No. 6 December 1997 1 of 7 by guest on November 13, 2017 http://pediatrics.aappublications.org/ Downloaded from