Highlights Malaria, Chagas' disease, and leishmaniasis are the parasitic diseases causing the highest morbidity/mortality rates and have a worldwide distribution. Efforts to develop effective vaccines are urgent. The insufficient efficacy of subunit vaccines has led to renewed interest in vaccination strategies based on live parasites. Natural immunization after infection is more the norm than the exception, as shown by the higher percentage of asymptomatic individuals observed in endemic areas.
