The thematic maps produced from the data on L. (N.) whitmani’s spatial distribution in Spatial Circuits of ACL Production associated to the different types of Brazilian vegetation showed a widespread distribution of the vector. This was mainly true for municipalities where Dense Ombrophilous Forests, Decidual Ombrophilous Forests, Seasonal Semidecidual Forests, Ecological Tension Areas, Savanna and Steppe vegetation were predominant. The variety of vegetation types where the vector was found indicates its capacity to endure wide environmental variations and to expand to new areas, as described by Costa et al. [16]. These results reinforce the theory of vector presence in all Brazilian biomes, except for the Pampa, as previously suggested by Costa et al. [17] and Rangel et al. [18]. The fact that the vector occurred in all Brazilian states, except for Santa Catarina and Rio Grande Sul, also contributed for this study to conclude that the vector adapts smoothly to different types of vegetation, including environmentally impacted areas, where important Spatial Circuits of ACL are found. This conclusion supports studies performed by Costa et al. [6] on the widespread geographic distribution of L. (N.) whitmani in association with forest, cerrado and caatinga areas.
The great region of Tucuruí (C4) encloses areas in the states of Pará, Maranhão and Tocantins and suffers from great environmental impact due to external interventions, containing a high concentration of ACL human cases. In this region, L. (N.) whitmani is the predominant vector species, inhabiting both wild and human-occupied spaces [19, 6, 3]. In Tocantins, the applicable Spatial Circuit of ACL did not enclose the entire state. However, given the percentage of human cases of ACL resulting from human action (the construction of hydroelectric plants, agricultural activities and the establishment of settlements), it can be said that the disease has a powerful impact in the state. These human activities are likely to have enabled or facilitated the spread of L. (N.) whitmani to 136 out of the 139 municipalities that compose Tocantins [20, 21].
In the North region, L. (N.) whitmani acted within eight Spatial Circuits of ACL production (C3, C4, C12, C13, C15, C16, C17 e C18), but especially in the states of Amazonas and Pará, transmitting L. (V.) shawi, and using monkeys (Cebus apella, Chiropotes satanas), “royal” sloths, "bentinha" (Choloepus didactylus e Bradypus tridactylus) and quatis (Nasua nasua) as hosts. In this region, the vector inhabits tree trunks of primary forests and bites avidly when disturbed [22, 15, 23, 24, 8]. To the north of the Amazon river, in the states of Amazonas, Pará and Roraima – where important ATL Spatial Circuits are located – and in Amapá – where there is no defined Spatial Circuit of ACL - L. (N.) whitmani transmits L. (V.) guyanensis. In these areas, the vector´s hosts are sloths (Choloepus didactylus), tamanduás (Tamandua tetradactyla), the marsupial Didelphis sp. and the rodent Proechimys sp. [15, 25, 22, 26]. Recent studies on natural infection have shown the transmission of L. (V.) guyanensis by L. (N.) whitmani in Monte Dourado (PA), which brings back a discussion proposed by Lainson [27] on the taxonomic status of this vector [14].
Leishmania (V.) braziliensis is the main responsible for ACL in the northeast, southeast, south and center-west regions of Brazil. Important Spatial Circuits are located in the states of Maranhão, Ceará, Pernambuco, Bahia, Minas Gerais, Espírito Santo and Paraná. In these states, the populations of L. (N.) whitmani can be found in different environments and possess two fundamental criteria in the evaluation of phlebotomines´ vectoral competence: a spatial distribution that coincides with human cases of ACL, and anthopophilia due to the vector´s presence in peri-domiciliary environments [28, 29, 26, 5, 7].
Lutzomyia (N.) whitmani is capable of adapting and surviving deforestation in several regions of Brazil. This species´ presence has been recorded in Mata Atlântica Reserves, in the Amazon, in Cerrado, Caatinga, and Pantanal. But also in peri-domiciliary environments, where residential areas are close to forests [30, 6, 17]. Recently, Costa et al. [16] have performed a study on climate adequacy, and they indicate the south as the most conducive direction for future presence of L. (N.) whitmani. The authors also predict an expansion of the vector to the North region, particularly in the state of Amazonas, in spite of the drought foreseen for this region, with an intensification and expansion of the dry season [31]. The authors sustain that L. (N.) whitmani will remain in the North, and will maintain a larger area of climactic adequacy.
Compared to other regions in the country, the L. (N.) whitmani presents a distinct behavior in the North. There, the species was considered to be mainly wild, being captured in tree trunks and treetops, with low interest in biting humans [25]. Studies in the following years confirmed these observations, and suggested that, if this species was anthropophilic, this would only be the case in specific situations [29, 28]. According to the results of the present study for the North of Brazil, spatial circuit 12 is present in the region, associated with Open Ombrophilous Forests. This type of vegetation is associated with a relatively dry climate, predominant in 2 to 4 months per year, with temperatures ranging from 24 to 25°C. Other than the North region, this type of vegetation can also be found in the states of Bahia, Espírito Santo, Alagoas, Pernambuco and Paraíba [32]. Circuit 12 also encompasses an area of Dense Ombrophilous Forests. This vegetation’s main ecologic trades are the records of the highest temperatures and most abundant rainfall indexes of the littoral and Amazonic regions. Here, rainfalls are well distributed throughout the year, contributing to a bioecological context where there is barely any dry period (consisting in 0 to 60 days per year) [33]. As evidenced by the dissonant characteristics of these two types of vegetation, the L. (N.) whitmani is capable of adapting to very diverse environments. This vector´s role in ACL transmission in diverse epidemiologic patterns throughout Brazil has made the L. (N.) whitmani the single most important vector of ACL in the country. This vector is associated to three parasites of ACL: L. (V.) braziliensis, L. (V.) shawi and L. (V.) guyanensis.
Costa et al. [16] report that ACL tends to expand to the Northwest of Brazil, and that the disease is linked to recent deforestation areas. In old human occupation areas, the endemic character of the disease is closely related to modified residual forests, and in newer occupation areas, this endemic character is connected to the development of productive activities in contact with woods in their original form [8].
Lutzomyia (N.) whitmani is a species that can transmit ACL in both types of occupied areas: recent and old. This vector is responsible for the circulation of L. (V.) braziliensis, a species of parasite with a wider distribution and with a different epidemiology from L. (V.) shawi and L. (V.) gyanensis [34, 7]. As it transmits L. (V.) braziliensis, L. (V.) shawi and L. (V.) guyanensis; L. (N.) whitmani is considered the main vector of ACL in Brazil. It is found in areas with various types of vegetation cover - be they natural or impacted by human action -, and it is associated with important Spatial Circuits of ACL Production.
In order to locate the municipalities with ACL transmission, the Program of Tegumentary Leishmaniasis Vigilance (PV-LT) classifies municipalities into five categories, based on the composite indicator of tegumentary leishmaniasis (ICLT). The categories are: sporadic transmission, moderate transmission, low intense transmission, average intense transmission and high intense transmission [8]. The results obtained through the association of L. (N.) whitmani with Brazilian vegetation types, in the states where important Spatial Circuits of ACL Production occur can be converted into ICLT categories, as long as magnitude and incidence of the disease in each municipality is known.