Leishmaniasis in Brazil: VI. Observations on the seasonal variations of Lutzomyia flaviscutellata in different types of forest and its relationship to enzootic rodent Leishmaniasis (Leishmania mexicana amazonensis)

Abstract

The seasonal fluctuation of Lu. flaviscutellata is shown to be closely related to rainfall, the population of this species declining during the rainy season, between May and March, and increasing again during the dry season, reaching a peak towards December and January. A comparison of the numbers of Lu. flaviscutellata caught in different types of forest showed that this species is more common in the wetter forests of the “igapo” than in the drier “terra firme” forests, although similar seasonal fluctuations are noted in both types of forest. The close correlation between the numbers of Lu. flaviscutellata and the incidence of initial infections of Leishmania mexicana amazonensis in Oryzomys capito indicates that the major factor controlling the incidence of leishmaniasis is the number of sandflies.