CHAGAS-DISEASE, AFRICAN TRYPANOSOMIASIS, AND LEISHMANIASIS

American trypanosomiasis (Chagas' disease), African trypanosomiasis (sleeping sickness), and leishmaniasis are caused by protozoan parasites primarily transmitted to humans by insects. These illnesses are major public health problems in many developing countries. Development of effective programs for reducing transmission of these pathogens has been difficult, and treatment continues to be problematic. American trypanosomiasis is widespread in almost all Latin American countries, and transmission by insects and through transfusion of blood donated by infected persons causes many thousands of new cases each year. Research involving novel approaches to the diagnosis and treatment of Chagas' disease is being done in many countries, but recent achievements in the laboratory have not yet resulted in major changes in the way this illness is diagnosed or treated. Similarly, our understanding of the immunology of leishmaniasis and the genetics of the organisms that cause its three forms has expanded greatly in recent years, but this new knowledge has not found its way into practical applications. In contrast, the approval this past year of eflornithine, the first new drug for African trypanosomiasis in decades, offers the hope of markedly reduced mortality due to the West African form of sleeping sickness. Even with the addition of eflornithine to the group of drugs useful for African trypanosomiasis, however, a need persists for less toxic agents that are effective when given for shorter periods. Rational drug design projects involving the most recent technologies from several disciplines may provide the next generation of drugs for the treatment of African trypanosomes and other protozoa that cause human diseases.