**2. American visceral leishmaniasis and** *Lutzomyia (Lutzomyia) longipalpis* **in Tocantins**

Tocantins is the newest of the 26 Brazilian states, its territory has 277,720.567 square kilometers, and it is located in the geographical center of the country, in the North Region (**Figure 1**). Most of the state is made up of plains and plateaus, and it has the largest river basin in the entire country, the Tocantins-Araguaia basin. Tocantins is one of nine states that form the Amazon region, its vegetation consists of 88% of the Cerrado biome and 12% of the Amazon biome (**Figure 1**). It has a semihumid tropical climate with two seasons: wet and dry. Its annual average temperature varies between 25°C and 29°C and average rainfall is around 1200–2100 mm [21, 22]. Among the phytoecological regions found in the state, the savannah (52%) and pasture (27%) are the majority [21, 23].

In the last decade, the state of Tocantins has suffered environmental changes from agricultural activities and construction of hydroelectric plants. In such scenarios, high numbers of human cases of leishmaniasis were recorded [24]. To quantify and describe the spatial and temporal distribution of AVL in Tocantins, the number of human cases recorded from 2000 to 2015 was provided by the Health Department of Tocantins State [personal communication]. All maps and spatial analysis were performed in ArcGIS (version 10.4).

In the analyzed period, Tocantins State had records of 4476 human cases of AVL in 124 of its 139 municipalities. From 2001 to 2013, 212 deaths were reported, and the municipalities Araguaína and Palmas (the state capital) reported 37% of the human cases of the state [24]. The spatiotemporal map (**Figure 2**) shows that human cases of AVL in the state are concentrated in the cities of Araguaína, Palmas, Porto Nacional, Paraíso do Tocantins, Araguatins, and Tocantinópolis, comprising 66% of the state's human cases. The municipality

**Figure 1.** Biomes of Tocantins State, Brazil. Source: IBGE. Map design: Laboratório Interdisciplinar de Vigilância Entomológica em Diptera e Hemiptera LIVEDIH/IOC/FIOCRUZ.

Ecoepidemiology of American Visceral Leishmaniasis in Tocantins State, Brazil: Factors Associated... http://dx.doi.org/10.5772/65852 95

**Figure 2.** Spatiotemporal profile of American visceral leishmaniasis human cases in the State of Tocantins, 2000–2015. Source: Health Department of Tocantins State. Map design: Núcleo de Geoprocessamento LIS/ICICT/FIOCRUZ.

**Figure 1.** Biomes of Tocantins State, Brazil. Source: IBGE. Map design: Laboratório Interdisciplinar de Vigilância

Entomológica em Diptera e Hemiptera LIVEDIH/IOC/FIOCRUZ.

94 The Epidemiology and Ecology of Leishmaniasis

**Figure 3.** Number of American visceral leishmaniasis human cases recorded in Araguaína municipality and in Tocantins State, 2000 –2015. Source: Health Department of Tocantins State.

Epidemiological surveillance is a major component of the Brazilian Control Program of Visceral Leishmaniasis (CPVL). The program has guidelines for stratifying municipalities under different categories, as areas with or without transmission of AVL. Through epidemiological analysis, health professionals and managers can thus classify the municipalities then adopt the adequate actions for monitoring, surveillance, and control of AVL [3].

According to the methodology proposed by the CPVL, municipalities with transmission are stratified according to the average of human cases reported in the last 3 years and then are categorized as sporadic, moderate, or intense transmission [3]. In Tocantins State, from 2004 to 2015, some municipalities remained classified as intense transmission, especially in the northern and central region, showing that the number of human cases remained high and constant throughout the years, especially in areas where there is high environmental impact (**Figure 4**).

From 2004 to 2015, intense transmission remained in the municipalities of Araguaína, Paraíso do Tocantins, Porto Nacional, and Palmas. However, municipalities such as Gurupi, Miracema do Tocantins, Nova Olinda, Araguatins, Carmolândia, Colinas do Tocantins, and Sampaio, in recent years, have moved from the sporadic or moderate category to the intense category, possibly due to environmental impacts. Other 57 municipalities were now classified as of sporadic transmission, originally being municipalities without transmission, comprising 50% of the municipalities with expansion of transmission. Only 15 municipalities, equivalent to 11% of the state, do not have transmission, and 34% of the municipalities have decreased the number of cases during the study period.

Ecoepidemiology of American Visceral Leishmaniasis in Tocantins State, Brazil: Factors Associated... http://dx.doi.org/10.5772/65852 97

of Araguaína is mainly responsible for the increased production of human cases in the state,

Epidemiological surveillance is a major component of the Brazilian Control Program of Visceral Leishmaniasis (CPVL). The program has guidelines for stratifying municipalities under different categories, as areas with or without transmission of AVL. Through epidemiological analysis, health professionals and managers can thus classify the municipalities then

**Figure 3.** Number of American visceral leishmaniasis human cases recorded in Araguaína municipality and in Tocantins

According to the methodology proposed by the CPVL, municipalities with transmission are stratified according to the average of human cases reported in the last 3 years and then are categorized as sporadic, moderate, or intense transmission [3]. In Tocantins State, from 2004 to 2015, some municipalities remained classified as intense transmission, especially in the northern and central region, showing that the number of human cases remained high and constant throughout the years, especially in areas where there is high environmental impact (**Figure 4**). From 2004 to 2015, intense transmission remained in the municipalities of Araguaína, Paraíso do Tocantins, Porto Nacional, and Palmas. However, municipalities such as Gurupi, Miracema do Tocantins, Nova Olinda, Araguatins, Carmolândia, Colinas do Tocantins, and Sampaio, in recent years, have moved from the sporadic or moderate category to the intense category, possibly due to environmental impacts. Other 57 municipalities were now classified as of sporadic transmission, originally being municipalities without transmission, comprising 50% of the municipalities with expansion of transmission. Only 15 municipalities, equivalent to 11% of the state, do not have transmission, and 34% of the municipalities have decreased

adopt the adequate actions for monitoring, surveillance, and control of AVL [3].

the number of cases during the study period.

State, 2000 –2015. Source: Health Department of Tocantins State.

96 The Epidemiology and Ecology of Leishmaniasis

with the temporal pattern of human cases matching the state's pattern (**Figure 3**).

**Figure 4.** Spatiotemporal profile of the stratification of municipalities for American visceral leishmaniasis in Tocantins State, 2004–2015. Source: Health Department of Tocantins State. Map design: Núcleo de Geoprocessamento LIS/ICICT/ FIOCRUZ.

To characterize the municipalities with the presence of the vector *L. (L.) longipalpis*, a literature search was held in the following databases: LILACS [25], MEDLINE [26], and SciELO [27]; using the keywords [28]: *Lutzomyia*, American visceral leishmaniasis, *L. (L.) longipalpis*, and Tocantins. Searches were also performed for conference abstracts, theses, dissertations, and monographs, and unpublished information was provided by the Health Department of Tocantins State [personal communication].

For the municipalities without information on the vector, it was assumed that *L. (L.) longipalpis* occurs where there are human cases of AVL, because so far *L. (L.) longipalpis* is the only vector species associated with the disease in the state of Tocantins and there is no record of *L. (L.) cruzi* in the state [personal communication Health Department of Tocantins State]. While this assumption does introduce a minor uncertainty in the analyses, not considering the presence of the vector in areas where AVL transmission is well-known would compromise the results.

From the scarce bibliographic records that were found (9), the vector was recorded in only 22 municipalities of Tocantins [29–37]. In contrast, there are records of human cases in 124 municipalities, which demonstrate the lack of entomological studies in the state (**Figure 5**).
