"In this work, we showed the irreversible leishmanicidal activity of the E. purpurea extract, by incubating the parasite for 30 min in a medium with the extract followed by culturing in a fresh medium. This suggests a metabolic injury that could not be reversed. Therefore the extract of Echinacea can be used both orally (for immunostimulation) and topically (for wound healing) in leishmaniasis. At present we are working on a project to find the active leishmanicidal compound(s) of the extract and the mechanism (s) of action." http://ijpr.sbmu.ac.ir/?_action=articleInfo&article=713
Keep in mind that the parasites were put into a medium that contained Echinacea extract. In other words, a much higher concentration than can be acheived by ingesting the extract. But it might be a good topical treatment for the "skin-only" type of this disease.