**1. Introduction**

[42] Rutledge LC, Ellenwood DA. Production of Phlebotomine sandflies on the open for‐

[43] Hanson WJ. The immature stages of the subfamily Phlebotominae in Panama (Dip‐

[44] Geoffroy B, Dedet JP, Lebbe J, Esterre P, Trape JF. Note sur les relations des vecteurs de leishmaniose avec les essences forestieres en Guyane Française. Ann Parasitol

[45] Cabanillas MRS, CastellónEG. Distribution of sandflies (*Diptera: Psychodidae*) on Treetrunks in a Non-flooded area of the Ducke Forest Reserve, Manaus, AM, Brazil*.* Me‐

[46] Apostila UFPE 2013.http://www.ufpe.br/biolmol/Leishmanioses-Apostila\_on\_line/

[47] Teodoro U, Vicent LSF, Lima EM, Misuta NM, Silveira TGV, Ferreira MEMCF. American cutaneous leishmaniasis: phlebotominae of the area of transmission in the

[48] Teodoro U, Thomaz-Soccol V, Kühl JB, Santos DR, Santos ES, Santos AR, Abbas M, Dias AC. Reorganization and cleaness of peridomiciliar area to control sand flies (Diptera, Pschodidae, Phlebotominae) in South Brazil. Arquivos Brasileiros de Biolo‐

North of Paraná, Brazil. Revista de Saúde Pública 1991;2(25) 129-33.

est floor in Panama: The species complement. EnvEntomol. 1975; 471-7.

tera: Psychodidae). PhD thesis.University of Kansas; 1968.

mórias do Instituto Oswaldo Cruz 1999; 94(3) 289-96.

Hum Com. 1986; 61(4) 491-05.

124 Leishmaniasis - Trends in Epidemiology, Diagnosis and Treatment

giaTecnológica 2004; 2(47) 205-12.

infogerais.htm.

#### **1.1. Leishmaniasis**

Leishmaniasis is a vector-borne disease transmitted by numerous sand fly species caused by obligate intracellular parasitic protozoa of the genus Leishmania. It can infect besides the man, a wide range of sylvatic and domestic mammal hosts producing either tegumentar or visceral lesions.

The life of *Leishmania* get going, when phlebotomine sand flies, mostly *Lutzomyia* in the New Word and *Phlebotomus* in the Old Wold, become infected during the blood meal, by ingesting infected mononuclear phagocytic cells. The amastigotes in the gut of sand flies, differentiates into promastigotes and multiply. In the *Viannia* subgenus the parasites develop in the hindgut of the vectors while in the *Leishmania* subgenus, the growth occurs in the midgut. In the insect's gut several promastigotes differentiate into metacyclic forms and migrate to the proboscis.

The parasites are transmitted by the bite of infected female of phlebotomine sand flies during the blood meal when the insects inject from their proboscis, the metacyclic promastigotes. Those forms are capable to survive inside the phagolysosomes of macrophages and other types of mononuclear phagocytic cells. Once inside of the cells, promastigotes differentiate into amastigotes, a stage that is associated mammal tissues. The amastigotes multiply by simple division and continue to infect other mononuclear phagocytic cells (Figure 1).

© 2014 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**Figure 1.** Life cycle of *Leishmania.*

Depending on the parasite and host species in addition to numerous factors related to the hosts' genetic background, the progress of the infection might be influenced, determining if the patient will become symptomatic or sick, eventually resulting in cutaneous or visceral leishmaniasis.

The geographical distribution of leishmaniasis includes 88 countries and almost 350 million of peoples live in these areas where the disease has been considered one of the most severe problem of public health. The majority of the countries affected are in the tropics and sub‐ tropics, consequently leishmaniasis covers a wide range from rain forests in Central and South America to deserts in West Asia [1,2] (Table 1 and 2).

Depending on the eco-epidemiological conditions, the leishmaniasis can present sylvatic or domestic transmission cycles (Figure 2). Among the most important factors composing those conditions, we could mention the environmental characteristics (biotic and abiotic factors) as well as the parasite, vector and host species involved.

The sylvatic cycles are quite ancient; they have been molded for millions of years before the emergence of man, through co evolutionary relationships among the parasite, vectors and The Geospatial Approach on Eco-Epidemiological Studies of Leishmaniasis http://dx.doi.org/10.5772/57210 127


**Table 1.** The main species of *Leishmania* from the Old World: with the correspondent clinical forms, regions of occurrence, vectors and mammal hosts. (? - Not known).


**Figure 1.** Life cycle of *Leishmania.*

126 Leishmaniasis - Trends in Epidemiology, Diagnosis and Treatment

America to deserts in West Asia [1,2] (Table 1 and 2).

well as the parasite, vector and host species involved.

leishmaniasis.

Depending on the parasite and host species in addition to numerous factors related to the hosts' genetic background, the progress of the infection might be influenced, determining if the patient will become symptomatic or sick, eventually resulting in cutaneous or visceral

The geographical distribution of leishmaniasis includes 88 countries and almost 350 million of peoples live in these areas where the disease has been considered one of the most severe problem of public health. The majority of the countries affected are in the tropics and sub‐ tropics, consequently leishmaniasis covers a wide range from rain forests in Central and South

Depending on the eco-epidemiological conditions, the leishmaniasis can present sylvatic or domestic transmission cycles (Figure 2). Among the most important factors composing those conditions, we could mention the environmental characteristics (biotic and abiotic factors) as

The sylvatic cycles are quite ancient; they have been molded for millions of years before the emergence of man, through co evolutionary relationships among the parasite, vectors and **Table 2.** The main species of *Leishmania* from the New World: with the correspondent clinical forms, regions of occurrence, vectors and mammal hosts. (\*- Putative).

mammal hosts. Mammal reservoirs and insect vectors have been continuously maintaining the parasites in equilibrium without human involvement.

In our time sylvatic cycles are restricted to wild places where disease outbreaks can eventually occur when people make incursions or settlements in those areas.

Concerning to domestic cycle an intra-domiciliary type (figure 2) of transmission is charac‐ teristic and the principal components for the disease establishment and maintenance, are the occurrence of vectors with the capacity of domiciliary human landing/biting, besides humans and domestic animals as mammal hosts [2].

**Figure 2.** Schematic drawing: eco-epidemiological picture of transmission cycles of Leishmanias.

The earliest steps for the origin of domestic cycles of leishmaniasis probably started around 12.000 years ago, when the ancient human populations began to practice sedentary agriculture and also have introduced domestic animals and livestock causing drastic alterations on the natural habitats.

As a result of such environmental modifications, a large avoidance of the sylvatic animals occurred from the surroundings of human habitations; that together with the insertion of new potential mammal hosts gave rise to a progressive adaptation process in some populations of sylvatic vectors toward a domiciliary behavior. Then little by little certain sand flies popula‐ tions adopted some introduced species as their new feeding sources [2-4].

In our time, after thousands of years of interaction with domestic mammals as hosts, some vectors hosts species that originally were totally sylvatic, have evolved to exist even in great urban areas, permitting the transmission of the parasite and its maintenance practically restricted to the participation of domestic and/or synanthropic hosts, sand fly and the man [5-7].

So, actually the eco-epidemiological picture of leishmaniasis could be represented as a complex puzzle where each piece is formed by the interaction of a parasite species with their correlated hosts and vectors, in a determined habitat. Nevertheless, it should not be considered as a static process because the occurrence of other parasite species, besides the action of the temporal component they can play a very important role, by influencing the whole process making it possible the occurrence of a variety of transmission patterns that sometimes may result in disease.

Considering the several difficulties to elaborate Leismaniasis control plans, probably the most significant is the high complexity of eco-epidemiological features of the disease. They are greatly influenced by the wide distribution of the parasites, the existence of a large variety of vector species in addition to the pressure of local environmental factors affecting the popula‐ tions of human hosts, vectors and reservoirs [3-4,8].

The leishmaniasis control measures in use, including spraying to eliminate the adult forms of the vector, diagnosis and treatment of human patients and elimination of seropositive dogs, have failed in preventing new epidemics [9,10].

Therefore, a spatial and temporal approach to analyze endemic foci of the disease could be very a useful method to understand the dynamic of transmission [11,12].

#### **1.2. Methods**

mammal hosts. Mammal reservoirs and insect vectors have been continuously maintaining

In our time sylvatic cycles are restricted to wild places where disease outbreaks can eventually

Concerning to domestic cycle an intra-domiciliary type (figure 2) of transmission is charac‐ teristic and the principal components for the disease establishment and maintenance, are the occurrence of vectors with the capacity of domiciliary human landing/biting, besides humans

the parasites in equilibrium without human involvement.

and domestic animals as mammal hosts [2].

128 Leishmaniasis - Trends in Epidemiology, Diagnosis and Treatment

natural habitats.

and the man [5-7].

occur when people make incursions or settlements in those areas.

**Figure 2.** Schematic drawing: eco-epidemiological picture of transmission cycles of Leishmanias.

tions adopted some introduced species as their new feeding sources [2-4].

The earliest steps for the origin of domestic cycles of leishmaniasis probably started around 12.000 years ago, when the ancient human populations began to practice sedentary agriculture and also have introduced domestic animals and livestock causing drastic alterations on the

As a result of such environmental modifications, a large avoidance of the sylvatic animals occurred from the surroundings of human habitations; that together with the insertion of new potential mammal hosts gave rise to a progressive adaptation process in some populations of sylvatic vectors toward a domiciliary behavior. Then little by little certain sand flies popula‐

In our time, after thousands of years of interaction with domestic mammals as hosts, some vectors hosts species that originally were totally sylvatic, have evolved to exist even in great urban areas, permitting the transmission of the parasite and its maintenance practically restricted to the participation of domestic and/or synanthropic hosts, sand fly Geographic information systems (GIS) and remote sensing (RS) are important tools that comprise computational systems, which permit to map and analyze environmental factors related to the spatial and temporal distribution environmental components that affect the distribution of diseases [12]. The availability of climatic, geological and phytographic digital data and the accessibility of GIS software also have permitted the implementation of several epidemiological studies in relation to ecological factors and disease prediction, as well as have been providing evidences that its use is indispensable before the elaboration of control plans [5, 11,12].

As examples of GIS software we could mention: ArcGis, TerraView, TerraHidro, Gvsig, etc.

The Remote Sensing is also an important data resource for presentation of vegetation, land cover and land use as well as the categorization of the habitats and population density of insect vectors, parasite and reservoir hosts [12,13].

An important feature available in GIS methodology consists of Kernel's method. It is consid‐ ered a new class of pattern analysis algorithms also utilized in GIS, which can operate on a wide-ranging types of data and relationships. Correlation, factor, cluster and discriminant analysis are just some of the types of pattern analysis tasks that can be performed on data as diverse as sequences, text, images, graphs and of course vectors. The method provides also a natural way to merge and integrate different types of data [5,14].

Kernel density estimators belong to a class of estimators called *non-parametric* density estima‐ tors. In comparison to parametric estimators where the estimator has a fixed functional form (structure) and the parameters of this function are the only information we need to store, Nonparametric estimators have no fixed structure and depend upon all the data points to reach an estimate [15].

Differently from conventional histograms where it is necessary to sub-divide the whole data in equal intervals and also to determine the end point of each interval, producing a not smooth representation. On the kernel method those problems can be minimized by the production of a kind of smooth histogram [15] (Figure 3).

**Figure 3.** Depiction of doghouses geo-referenced and canine leishmaniasis cases in function of serological titers, rep‐ resented by histograms and Kernel method (ArcGis).

Other attributes of GIS methodology very useful to the study epidemiology of leishmaniasis is the possibility to create digital maps after performing cluster analysis on the populations of vectors and mammal hosts, including the man; and also to represent circumscribed areas in the same maps, indicating potential regions of vector flight or putative hosts' home ranges [11,14,16] (Figure 4 and 5).

Clustering is a method also applied in GIS, and comprises a common technique for statistical data analysis used in many fields, including machine learning, data mining, pattern recogni‐ tion image analysis and bioinformatics.

So, the use of new technologies based on eco-epidemiological indicators is essential on the identification of circumstances that impair the spread and maintenance of the disease and certainly could be used to set priorities for implementing disease control measures, thus reducing operational costs and increasing their effectiveness.

In conclusion, the notorious difficulty in controlling the transmission of leishmaniasis, a disease caused by a parasitic protozoa described at 1903 and that still persists currently showing a re-emerging pattern in some places, indicates that such parasites have been developing a great number of evolutionary advantages and despite all the efforts of scientists an effective control was not achieved yet. It is important to remember that those organisms

parametric estimators have no fixed structure and depend upon all the data points to reach an

Differently from conventional histograms where it is necessary to sub-divide the whole data in equal intervals and also to determine the end point of each interval, producing a not smooth representation. On the kernel method those problems can be minimized by the production of

**Figure 3.** Depiction of doghouses geo-referenced and canine leishmaniasis cases in function of serological titers, rep‐

Other attributes of GIS methodology very useful to the study epidemiology of leishmaniasis is the possibility to create digital maps after performing cluster analysis on the populations of vectors and mammal hosts, including the man; and also to represent circumscribed areas in the same maps, indicating potential regions of vector flight or putative hosts' home ranges

Clustering is a method also applied in GIS, and comprises a common technique for statistical data analysis used in many fields, including machine learning, data mining, pattern recogni‐

So, the use of new technologies based on eco-epidemiological indicators is essential on the identification of circumstances that impair the spread and maintenance of the disease and certainly could be used to set priorities for implementing disease control measures, thus

In conclusion, the notorious difficulty in controlling the transmission of leishmaniasis, a disease caused by a parasitic protozoa described at 1903 and that still persists currently showing a re-emerging pattern in some places, indicates that such parasites have been developing a great number of evolutionary advantages and despite all the efforts of scientists an effective control was not achieved yet. It is important to remember that those organisms

estimate [15].

a kind of smooth histogram [15] (Figure 3).

130 Leishmaniasis - Trends in Epidemiology, Diagnosis and Treatment

resented by histograms and Kernel method (ArcGis).

tion image analysis and bioinformatics.

reducing operational costs and increasing their effectiveness.

[11,14,16] (Figure 4 and 5).

**Figure 4.** Vegetation, land cover and land use patterns and general distribution of canine leishmaniasis cases, with the respective serological titers, from an endemic focus in Brazil (ArcGis).

**Figure 5.** Visual interpretation of an aerial mosaic of photographs from an endemic focus in Brazil, showing the area of influence of the vector flight and the general distribution of canine *Leishmania* infections in addition to the serolog‐ ical titers (source: website of the Pereira Passos Institute http://www.armazemdedados.rio.rj.gov.br/).

have been dwelling on earth for millions of years before of us and it certainly represents that they have skills we not elucidated yet.
