This work has several objectives. The first objective is to compare current "gold-standard" diagnostic techniques for these diseases with newer antigen detection and polymerase chain reaction techniques. The second objective is to delineate the protective role of innate and acquired immunity to E. histolytica. The investigators hypothesize that protective immunity is mediated both by innate immune responses initiated via Toll-like Receptor stimulation and acquired responses including mucosal immunoglobulin A (IgA) and systemic Interferon-γ. Acquired immune responses (peripheral blood mononuclear cell cytokine production and fecal IgA anti-cross reacting determinant) during amebic and cryptosporidial infection and disease will be determined in the children in the cohort. The third objective is to test for the association of genetic polymorphisms in innate and acquired immune genes with incidence of amebiasis. The investigators hypothesize that common genetic polymorphisms in genes of the innate and acquired immune system influence susceptibility to E. histolytica and Cryptosporidia infection or disease. The final objective is to test the role of human genetic polymorphisms and microbiome in protection from undernutrition. Genome wide scans and microbiome compositional analyses will be performed on children to determine if the nutritional status of the child correlates with these measurements.