A method for treating a microbial infection, including an infection from a protozoan pathogen, such as Trypanosoma brucei rhodesiense and Plasmodium falciparum, in a subject in need thereof by administering to the subject an effective amount of a dicationic imidazopyridine compound or a dicationic tetrahydro-imidazopyridine compound. Processes for synthesizing dicationic imidazopyridines and dicationic tetrahydro-imidazopyridines and the novel dicationic imidazopyridine and dicationic tetrahydro-imidazopyridine compounds themselves.