**3. Etiological agents and vectors**

In the Americas, 11 dermotropic species of *Leishmania* which cause the disease in humans are currently recognized and 8 species have been described as affecting only animals. However, in Brazil, 7 species, there being 6 of the subgenus *Viannia* and 1 of the subge‐ nus *Leishmania,* have been identified. The three main species are: *Leishmania ( Leishmania) amazonensis* - distributed throughout the primary and secondary forests of the Amazon (Amazonas, Pará, Rondônia, Tocantins and the southwest of Maranhão southwest), particularly in *igapó* and forest areas of the "swamp-forest" type. Its presence extends to the regions of the Northeast (Bahia), Southeast (Minas Gerais and São Paulo) and Midwest

(Goiás); *Leishmania (Viannia) guyanensi* - apparently limited to the north of the Amazon Basin (Amapá, Roraima, Amazonas and Pará) and extending to the Guianas. It is found mainly in *terra firme* forests in areas that do not flood during the rainy season; *Leishmania (Vian‐ nia) braziliensis* – is widely distributed, from the South of Pará to the Northeast, also reaching the center-south of the country and some areas of the Eastern Amazon East. In the Amazon, the infection is usually found in dry land areas.

As the subgenus *Viannia*, there are other species of *Leishmania* that have been recently descri‐ bed: *L. (V) lainsoni, L. (V) naiffi* with a few human cases in Pará; *L. (V) shawi,* with human cases found in Pará and Maranhão. More recently, the species *L. (V.) lainsoni, L. (V.) naiffi, L. (V.) lindenberg and L. (V.) shawi* were identified in states of the North and Northeast regions [8]. In areas of transmission of *L. braziliensis* concomitantly or after resolution of the cutaneous disease, about 3% of patients with cutaneous *Leishmania*sis will develop the mucosal form of the disease [3].

Mucosal Leishmaniasis (ML) is a form of tegumentary Leishmaniasis associated with *L. braziliensis, L. panamensis* and less frequently with *L. amazonensis* [11]. The vectors of ATL are insects known as phlebotominae, belonging to the order *Diptera*, *Psychodidae* family, sub-family *Phlebotominae*, genus *Lutzomyia*, popularly known, depending on the geographical location, as straw-mosquito straw, *tatuquira, birigui*, among others [8]. Generally not exceeding 0.5 cm in length, with long and spindly legs and a dense body follicles. A characteristic of theirs is a hopping flight and keeping their wings erect, unlike other dipteral [9]. The vectors are *Lutzomya anduzei, Lutzomyia whitmani* and *Lutzomyia umbratilis*, which is the main vector, which usually lands during the day on tree trunks and attacks people in large numbers, when disturbed [16]. It is usually brownish ("straw-mosquito"), only the females being adapted with the respective mouth part to prick the skin of vertebrates and suck blood.

The genus *Lutzomyia* is responsible for the transmission of Leishmaniasis in the Americas, and there are 350 species catalogued, which are distributed from the South of Canada to the North of Argentina. Of these, at least 200 occur in the Amazon basin. Very little is known of their breeding grounds, with immature forms being found in debris of rock crevices, caves, roots of the soil and of dead and damp leaves, and also in the forks of trees in animal burrows - ie in moist but not wet soil, and in debris rich in decaying organic matter [9].
