[Visceral leishmaniasis: clinical sensitivity and resistance to various therapeutic agents]

Visceral leishmaniasis is present in 61 countries but 90% of the 500,000 new cases that arise annually occur in five countries, i.e., India, Bangladesh, Nepal, Sudan, and Brazil. Annual mortality is approximately 59000 cases. Agents based on pentavalent antimony have been the mainstay of treatment for the last 60 years. In recent years, however, clinical resistance to these agents has been reported especially in the state of Bihar in India. Pentamidine and amphotericin B were introduced in the 1950s and 1960s. More recent additions to the therapeutic arsenal include liposomal amphotericin B, miltefosine, and paromomycin. Among these recent molecules, miltefosine, i.e., the only oral agent, appears most vulnerable because it involves long-term treatment and has a long half-life. The main therapeutic problems now being encountered are the emergence of acquired resistance to antimonials, the high cost of treatment, and failure of therapy in immunocompromised patients mainly due to concurrent human immunodeficiency virus (HIV) infection. For eradication initiatives such as the one aimed at eliminating leishmaniasis on the Indian subcontinent, the appearance of drug resistance increases the risk associated to parasite infection and, as for malaria, tuberculosis and HIV infection, raises fears that the problems in the implementation of public health policies will lead to highly refractory forms.