Background:  In early 2006, a severe outbreak of diarrhea occurred among young children, coinciding with heavy rains and widespread water contamination. Pediatric diarrhea surveillance reported 3.5 times the usual number of cases and 25 times the usual number of deaths between January and March. Cryptosporidium and enteropathogenic E. coli were the most common pathogens identified. Botswana is HIV prevalent among pregnant women (33.4% in 2005 surveillance), and the national program for prevention of mother-to-child transmission of HIV (PMTCT) provides free infant formula and advises HIV-infected women not to breastfeed. Many HIV^– women also bottle-feed their infants. An estimated 35% of all infants under the age of 6 months are not breastfed.

Methods:  All pediatric inpatients <5 years old with diarrhea in the country’s second-largest referral hospital from February 20 to March 10, 2006 were followed by chart review until April 10. Their mothers were interviewed, and mothers and infants were tested for HIV.

Results:  Of 154 diarrhea inpatients, 96% were <2 years old, 90% of those were not breastfed in the 2 weeks before illness, and 33 (21%) died. Among patients with HIV results, 23 of 131 (18%) were HIV infected and 93 of 144 (65%) had an HIV⁺ mother. Malnutrition was common:  of 99 children, 51 (52%) with growth records exhibited no growth in the previous 3 months; severe acute malnutrition (kwashiorkor or marasmus) developed in 38 of 147 (26%) during or after the diarrhea. Kwashiorkor was a significant risk factor for death (RR = 2.0, 95%CI 1.1 to 3.8) and tended to be more common in HIV^– children (27% vs 9%, RR 3.0, 95%CI 0.75 to 12.5). No breastfeeding children died (RR 6.1, 95%CI 0.39 to 93.4). HIV in mother or child was not a risk factor for death. Infants who died while receiving formula through the PMTCT program had received an average of 51% of the formula they should have received after birth, and 60% had not gained weight in the 3 months prior to illness.

Conclusions:  Most of the severe morbidity and mortality occurred in children who were HIV^–, not breastfeeding, and not growing well. Severe acute malnutrition following diarrhea was the most important predictor of death, and was associated with inadequate prior formula supply in some babies. Breastfeeding provides optimal nutrition and prevents diarrhea, and policy revisions to increase breastfeeding among HIV^– and HIV⁺ women should be considered.