An electromagnetic radiation (EMR) delivery system for delivering EMR at wavelengths, intensities, exposures, and durations to locations inside and/or outside a patient's body in, on, and surrounding a catheter and/or a catheter extension to prevent, reduce, and/or eliminate infectious agents in, on, or surrounding the catheter and/or catheter extension. A smart light engine box generates the therapeutic EMR, controls treatments, and monitors the health of the system. A fiber optic disposable makes at-home use of the EMR delivery system possible. Specific embodiments of the EMR delivery system for use with peritoneal dialysis catheters, dialysis accesses, and hemodialysis accesses are also disclosed.