We investigate the Susceptible-Infectious-Recovered contagion dynamics in a system of self-propelled particles with polar alignment . Using agent-based simulations, we show that the emerging spatial features strongly affect the contagion process, in addition to standard epidemic parameters given by the base reproduction number and duration of the individual infectious period . We find that the ordered homogeneous strongly disfavor the infection propagation, due to their limited mixing, and only propagate contagion for very high individual infectious periods . The disordered homogeneous states also display low contagion capabilities, requiring relatively high infection parameters to propagate the infection . Instead, the ordered inhomogeneous states display high contagion for a range of parameter values . In these states, the formation of bands and clusters favors contagion through a combination of processes that develop within and without these structures . Our results highlight the importance of the self-organized spatial dynamics in contagion processes, with implications for understanding of contagion process and its control in self-organized animal groups and human crowds.