Thermotherapy v. antimonials: what happens after the healing of cutaneous leishmaniasis lesions?

The long-term effects of meglumine antimoniate (chemotherapy) or exposure to an environmental temperature of 37 degrees C (thermotherapy) on the evolution of Leishmania mexicana infections and on the response to challenge infections six months after treatment were compared in susceptible (BALB/c) and partially resistant (C57BL/6) mice. Thermotherapy was better than chemotherapy in that it healed lesions quicker and prevented relapses in the partially resistant mice during the observation period. However, both treatments appeared equally effective in terms of clinical cure. Neither treatment cleared all parasites from the hosts and both impaired the hosts' immune response to a challenge infection. The results indicate that specific immunity fades with time post-infection and that the persistence of the parasite in a clinically cured host does not maintain protective immunity against challenge infections.