Development of vaccines against leishmaniasis.

A vaccine against leishmaniasis is the only practical means to control this disease in many epidemiological situations. Two approaches have been adopted: pragmatic and systematic. The pragmatic approach involves trial of crude leishmanial components in animals and then in humans if they meet safety requirements. The systematic approach requires identification of the protective immunogen(s), appropriate carrier and adjuvant, and determination of the immune responses and modes of presentation of the immunogens to achieve the desired effect. Progress have been made with both approaches. Killed Leishmania promastigotes have been used in Brazil for high risk individuals with encouraging results. Impressive results have also been observed with killed Leishmania plus BCG for immunotherapy of cutaneous leishmaniasis in Venezuela. With the systematic approach, recent research has identified some protective immunogens, cloned protective murine T-cells, developed primate models resembling the human disease, cloned and expressed genes of some potential immunogens, identified some features of the protective immune response, determined modes of presentation of immunogen to produce a protective response, and been able to protect mice (even/Balb/c) against L. major infection. The difficult part that remains is the implementation of a vaccine or any control measure in the poor communities where they are needed and where the lack of required infrastructure does not allow adequate coverage.