The epidemiology of visceral leishmaniasis in east Africa: hints and molecular revelations.

Visceral leishmaniasis appears in the form of notoriously devastating epidemics and as an endemic disease of sporadic nature. In an attempt to understand the nature of this difference and its underlying causes, and to identify possible mechanisms for the instigation of outbreaks, the current status of the characterization of the parasite, its taxonomy, host immunity and genetics, are reviewed with the main focus on eastern Africa, one of the places where the dichotomous epidemiology of the disease is most pronounced. The new molecular tools offer various insights into the understanding of the complex epidemiology of visceral leishmaniasis and the interplay between parasite and host factors. Further insights are also provided on the parts played by demography, genetic history and geography in shaping the overall global portrait of the disease.