Innate and Acquired Resistance to Amebiasis in Bangladeshi Children

Entamoeba histolytica infection and colitis occurred in 55% and 4%, respectively, of a cohort of Bangladeshi preschool children observed for 2 years. DNA typing demonstrated that infecting E. histolytica isolates were genetically diverse. Innate resistance to infection in children was linked to the absence of serum anti–trophozoite IgG. Most children who lacked serum anti–trophozoite IgG failed to develop it in response to a new infection. The serum anti–trophozoite IgG response clustered in families, which is consistent with genetic inheritance. Acquired resistance to infection was linked to intestinal IgA against the carbohydrate-recognition domain of the E. histolytica galactose N-acetyl-d-galactosamine lectin. This was associated with an 86% reduction in new infection over 1 year. Amebiasis is a common and potentially serious infection in children from Dhaka, and both innate and acquired immune responses limit infection