Leishmania is endemic in some areas but it’s not pandemic due to its need of a vector (the sandfly) that cannot reproduce in some areas.

Why is it easier to treat than HIV?, well the HIV can insert itself into the DNA of its host cell making it extremely difficult to completely eradicate; we can only control the mature viruses but we cannot remove its genetic code from infected cells; as for leishmaniasis, it’s a parasite for wich we have several medications and can be completely eradicated (but it’s not easy, sometimes lengthy IV treatments are needed).

Does the immune system have defenses against Leishmania?? Yes, the infected cells can express some particles in its membrane wich makes them recognizable to the acquired immune system, the infected cells are surrounded by a bunch of other cells causing a “granulomatous inflammation” containing the infection in a single place (most of the times, not always effective) that we can see in the form of skin ulcers or lumps inside the organs (depends of the leishmania type).

Can it be contain by the immune system to a single place? Yes. Can it resolve without treatment? Most likely not.