David Mabey of the London School of Hygiene and Tropical Medicine in the United Kingdom and his team will test whether treatment with the broad­-spectrum antibiotic azithromycin can prevent growth faltering linked to environmental enteropathy, which is prevalent in young children of developing countries. They will utilize a double blind, randomized, controlled trial of Malawian children aged 1­-60 months, and analyze growth over a two year period after a single administration of either the antibiotic or a placebo control. They will also analyze immune responses and composition of the intestinal microbiota to identify the molecular pathways underlying environmental enteropathy. Their aim is to improve growth and development in affected infants in low­-income countries.