Cryptosporidium, an apicomplexan parasite which infects the small intestine, is a leading cause of diarrheal mortality in children under five. In our cohort of Bangladeshi children, repeated infections occur before immunity develops, typically by age four. Due to the lack of effective treatments for infants, understanding the initial failure of adaptive immune response is crucial for future vaccine development. We observed that T follicular helper (Tfh) cells, involved in B cell activation, show an exhaustion-like phenotype in 2-year-old Bangladeshi children – a pattern not observed in American children. In untreated PBMCs, we found a higher percentage of activated (CD40L+) Tfh cells at age 2 compared to age 1 and 3. However, Tfh cells at age 2 fail to increase in activation upon stimulation with PMA/Ionomycin, correlating with peak Cryptosporidium infection rates. To further investigate the role of Tfh cells in Cryptosporidium immunity, we assessed the functional capacity of memory Tfh cells using an antigen-induced marker (AIM) assay. We identified Cryptosporidium-specific Tfh memory cells in the peripheral blood mononuclear cells (PBMCs) of children aged 5 and 6 by upregulation of CD69, CD40L, CD134, and/or CD137 following stimulation with Cryptosporidium extract. Preliminary data showed a correlation between Tfh cell activation and the number of Cryptosporidium infections by age five. Children who exhibited a robust memory response to stimulation had fewer than 2 infections by age 5, while those who had a poor memory response had up to 7 (p=0.0079). Additionally, children with a robust Tfh cell memory response tended to have high concentrations of Cryptosporidium-specific antibodies, whereas those with low concentrations did not (p=0.0479). These results suggest that highly functional memory Tfh cells are essential for effective antibody production and subsequent protection, highlighting their potential importance in the development of immunity to Cryptosporidium.