Background:  From January until March 2006, during a period of heavy rainfall, Botswana reported a 4-fold increase in diarrhea cases and a 25-fold increase in diarrhea deaths in children <5 years old compared with 2004 to 2005. A mulitidisciplinary team investigated the outbreak at a large hospital.

Methods:  We reviewed inpatient records, interviewed caregivers, and tested stool specimens for enteric pathogens. A case-control study compared children in the emergency department for diarrhea with those who had other illnesses. A community survey examined diarrhea, malnutrition, and death rates in the surrounding community.

Results:  Among 154 inpatients with diarrhea, 96% were <2 years old; 90% of those were not breastfeeding. Of children <1 year old, half were receiving free infant formula through Botswana’s national program for prevention of mother-to-child transmission of HIV. Of the 144 with test results, 93 (65%) had HIV-positive mothers, and 23 of 131 (18%) were HIV-infected. Cryptosporidium, enteropathogenic E. coli, and Salmonella were the most commonly identified pathogens. Medical records indicated that half of the patients had poor growth before the illness, 30 of 147 (20%) developed kwashiorkor, and 32 of 154 (21%) died. Children who developed kwashiorkor had higher mortality (37% vs 17%, p = 0.03). No breastfeeding children died, compared with 28 of 122 (23%) of non-breastfeeding children. The case-control study included 56 cases and 72 controls. After adjusting for socioeconomic status and age, not breastfeeding was the most significant risk factor for having diarrhea. Storing household drinking water, overflowing latrines near the home, and caregivers not washing their hands after using the toilet were also associated with diarrhea. The community survey indicated that diarrhea was twice as common among children who were not breastfed, that acute malnutrition was more common than previously reported in Botswana, and that the estimated under-5 death rate during the outbreak was 4 times the historical death rate.

Conclusions:  During a multi-pathogen outbreak of diarrhea in Botswana, non-breastfed children under 2 years old were most affected, and malnutrition contributed to high mortality. Careful attention to water quality, sanitation, hygiene, and nutrition is essential for children who are not breastfeeding. Support for increased breastfeeding among HIV-positive and HIV-negative women may reduce the risk of another serious outbreak.