Assessing the Impact of Unnecessary Antibiotic Treatment on the Development of Appropriate Adaptive Immune Responses in Malnourished Bangladeshi Infants

The investigators are examining the role of circulating T follicular helper (Tfh) cellsin the induction of the antibody responses. The investigators hypothesize that Tfh cellactivation is impaired in Bangladeshi children and that this activation failure isassociated with a history of antibiotic use. The results of the investigators'preliminary studies suggest that antibiotic treatment could have a detrimental effect onthe development of an appropriate adaptive immune response against Cryptosporidium.Antibiotic treatment for children with cryptosporidiosis, rotavirus and adenovirus40/41is not currently recommended (supportive therapy only), although usually given tochildren in Dhaka, Bangladesh. This study will randomly assign children with diarrhea dueto Cryptosporidium, rotavirus or adenovirus 40/41 to two groups. Supportive treatmentwould be provided in both groups, but in group #1, antibiotic treatment would be withheldwhile group #2 will receive usual care which normally will include antibiotic treatment.The investigators will monitor the children for one year to measure T follicular helperfunction, antibody production, and reinfection.