CD34 and infection: Here we report the infection of CD34+ umbilical cord blood hematopoietic stem cell engrafted humanized NSG mice with S. stercoralis, the successful infection of such humanized NSG mice with HTLV-1, and the coinfection of S. stercoralis and HTLV-1 in these humanized NSG mice with resultant alterations in cytokine responses and parasite development.