EIF5A and parasitic infectious disease: This study has also provided an answer to a long-standing conundrum on the biological importance of polyamines: spermidine is needed for eIF5A hypusination, which is essential for protein translation in Entamoeba. Our work will provide an insight into the physiological significance of eIF5A and its post-translational modifications in other pathogenic eukaryotes and potentially lead to the formulation of control measures against parasitic diseases.