**3. Geographical variables**

#### **3.1. Worldwide variables**

In the terms of biosphere, geographical variables of leishmaniasis transmission are associated with tropical zone as well as hot and the wet climates with regular pluvial index [10]. The countries that are underdeveloped as well as the developing countries show the highest incidence of leishmaniasis transmission (figures 3 and 4).

Indeed, both human LV and LC follow the geographical distribution of the insect vector (see [15] ); it is found globally between tropics but has also been detected in some regions with relatively rigorous winter such as in France [16], Portugal, Russia and China [3].

Based on the information available since past ten years, in Africa, the data on reported cases of LV are sparse and the reported cases in sub-Saharan African region are scarce (table 1); Nigeria had just one reported case within this period [3]. However, in Eastern African countries, LV is endemic and the reported cases have increased above predicted expectation in the last 20 years [9]. The countries with the most infections are Sudan [17, 18], Ethiopia [2, 9], South Sudan [3], Somalia, Uganda, Kenya [9] and Eritrea [3] (table 1, figures 3 and 4).

As for LC, Sub-Saharan region (figures 3 and 4) showed elevated number of the reported cases than cases for LV, i.e., 154 cases of LC in comparison to 1 case of LV; whereas the countries with higher number of LC cases are Cameroon and Nigeria respectively. In Eastern Africa, interestingly, Eritrea is the country with the lowest cases of LV and the highest cases of LC, while other countries in this region have no reported cases in the past ten years (table 1). In general, in African subcontinent, the number of reported cases of LV is much higher than those of LC, i.e., 8,571 of LV in comparison to 204 of LC.

**Figure 3.** World LV distribution in the last 10 years.

**2. Materials and methods**

108 Leishmaniasis - Trends in Epidemiology, Diagnosis and Treatment

**2.1. Inclusion criteria**

**2.2. Exclusion criteria**

contents as the most recent papers used here.

incidence of leishmaniasis transmission (figures 3 and 4).

of LC, i.e., 8,571 of LV in comparison to 204 of LC.

**3. Geographical variables**

**3.1. Worldwide variables**

The goal of this chapter is to collect the information from an extensive literature using the followings electronic databases: MEDLINE, Plos, PubMed, LILACS, CAPES periodic, Open Journal System, Scielo and Google Academic. The descriptors used were*: leishmaniasis, leishmaniasis visceral, leishmaniasis cutaneous, leishmaniasis mucocutaneous, Phlebotomine, the sand flies, the geographical aspects of leishmaniasis* and the *environmental aspects of leishmaniasis*.

Indexed papers published in the last 20 years; classic indexed papers on more ancient and

Papers that did not mention the main ideas used in this chapter and the texts with the same

In the terms of biosphere, geographical variables of leishmaniasis transmission are associated with tropical zone as well as hot and the wet climates with regular pluvial index [10]. The countries that are underdeveloped as well as the developing countries show the highest

Indeed, both human LV and LC follow the geographical distribution of the insect vector (see [15] ); it is found globally between tropics but has also been detected in some regions with

Based on the information available since past ten years, in Africa, the data on reported cases of LV are sparse and the reported cases in sub-Saharan African region are scarce (table 1); Nigeria had just one reported case within this period [3]. However, in Eastern African countries, LV is endemic and the reported cases have increased above predicted expectation in the last 20 years [9]. The countries with the most infections are Sudan [17, 18], Ethiopia [2, 9], South Sudan [3], Somalia, Uganda, Kenya [9] and Eritrea [3] (table 1, figures 3 and 4).

As for LC, Sub-Saharan region (figures 3 and 4) showed elevated number of the reported cases than cases for LV, i.e., 154 cases of LC in comparison to 1 case of LV; whereas the countries with higher number of LC cases are Cameroon and Nigeria respectively. In Eastern Africa, interestingly, Eritrea is the country with the lowest cases of LV and the highest cases of LC, while other countries in this region have no reported cases in the past ten years (table 1). In general, in African subcontinent, the number of reported cases of LV is much higher than those

relatively rigorous winter such as in France [16], Portugal, Russia and China [3].

severe areas. Some textbooks have also been used to elaborate this chapter.

**Figure 4.** World LC distribution in the last 10 years.


**Table 1.** Geographical distribution of LV and LC in Africa based on reference [3].

In Asian subcontinent from the Middle East to Central Asia, significant LV prevalence was only found in Iraq with more than 1,000 reported cases; in China, Georgia and Iran the reported cases ranged at little over 100. In this Asian region, the reported cases of LC are much higher than those of LV, i.e., 61,015 of LC in comparison to 2,497 of LV. As regards to LC, more than 1,000 cases were reported in Iran, Afghanistan, Pakistan, Saudi Arabia and Iraq; and in Yemen and Uzbekistan the number of reported cases was over 100 (table 2) (figures 4 and 5).

In Indian subcontinent [3, 20] and in Southwestern Asia [3, 21], there are more than 1,000 reported LV cases in countries like India, Bangladesh and Nepal; in this same territory LC cases higher than 100 in number have only been reported in Sri Lanka and India. The reported total LV cases are higher than LC cases in Indian Subcontinent and in Southeastern Asia, i.e., 42,623 of LV in comparison to 478 of LC (table 2, figures 4 and 5).

In Asia, overall number of the reported LC cases is higher than those of LV cases, i.e., 61,493 of LC while 45,120 of LV.


**Table 2.** Geographical distribution of LV and LC in Asia based on reference [3].

**Reported cases in Africa**

*Sub-Saharan African region*

*Eastern African region*

In Asian subcontinent from the Middle East to Central Asia, significant LV prevalence was only found in Iraq with more than 1,000 reported cases; in China, Georgia and Iran the reported cases ranged at little over 100. In this Asian region, the reported cases of LC are much higher than those of LV, i.e., 61,015 of LC in comparison to 2,497 of LV. As regards to LC, more than 1,000 cases were reported in Iran, Afghanistan, Pakistan, Saudi Arabia and Iraq; and in Yemen

In Indian subcontinent [3, 20] and in Southwestern Asia [3, 21], there are more than 1,000 reported LV cases in countries like India, Bangladesh and Nepal; in this same territory LC cases higher than 100 in number have only been reported in Sri Lanka and India. The reported total LV cases are higher than LC cases in Indian Subcontinent and in Southeastern Asia, i.e., 42,623

In Asia, overall number of the reported LC cases is higher than those of LV cases, i.e., 61,493

and Uzbekistan the number of reported cases was over 100 (table 2) (figures 4 and 5).

Eritrea 100 50 Ethiopia 1860 0 Kenya 145 0 Somalia 679 0 Sudan 3742 0 South Sudan 1756 0 Uganda 288 0 **Total 8570 50**

**Table 1.** Geographical distribution of LV and LC in Africa based on reference [3].

of LV in comparison to 478 of LC (table 2, figures 4 and 5).

of LC while 45,120 of LV.

Cameroon 0 55 Cote d'Ivore 0 1 Ghana 0 27 Mali 0 58 Nigeria 1 5 Senegal 0 8 **Total 1 154**

110 Leishmaniasis - Trends in Epidemiology, Diagnosis and Treatment

**Visceral leishmaniasis Cutaneous leishmaniasis**

In the Mediterranean region, countries with more than 100 reported LV cases are Morocco, Italy, Spain, Albania and Algeria; for LC, the countries with more than 1,000 reported cases are Algeria, Syria, Tunisia, Libya, Morocco and Turkey (table 3, figures 3 and 4). Israel, Egypt, Jordan and Palestine are on lower tier of LC prevalence, in these countries, over 100 LC cases have been reported (table 3, figures 3 and 4). Thus in this region, overall number of the reported LC cases is much higher than LV cases, i.e., 85,886 of LC in comparison to 874 of LV in the last ten years.


**Table 3.** Geographical distribution of LV and LC in the Mediterranean region based on reference [3].

In Latina America, the number of LV cases have increased in northern Argentina [22], in areas bordering Brazil and Paraguay, in Colombia [23], in Venezuela [24] as well as in North America [25] ; recently one case has been recorded in Uruguay as well [19] (table 4).

Brazil is the only country in the Americas with over 1,000 reported cases of LV, in other countries the reported cases of LV are lower than 100 (table 4). In contrast, LC is relatively widespread with 10 countries that have over 1,000 reported cases, these are Brazil, Colombia, Peru, Nicaragua, Bolivia, Venezuela, Panama, Ecuador, Costa Rica and Honduras in descend‐ ing order of prevalence. Additionally, 5 countries show over 100 reported cases, they are Mexico, Guatemala, Paraguay, Argentina and French Guyana respectively (table 4).

LC cases is much higher than LV cases, i.e., 85,886 of LC in comparison to 874 of LV in the last

**Reported cases in the Mediterranean region**

Albania 114 6 Algeria 111 44050

Bosnia and Herzegovina 2 0

**Table 3.** Geographical distribution of LV and LC in the Mediterranean region based on reference [3].

[25] ; recently one case has been recorded in Uruguay as well [19] (table 4).

In Latina America, the number of LV cases have increased in northern Argentina [22], in areas bordering Brazil and Paraguay, in Colombia [23], in Venezuela [24] as well as in North America

**Visceral leishmaniasis Cutaneous leishmaniasis**

ten years.

112 Leishmaniasis - Trends in Epidemiology, Diagnosis and Treatment

An interesting aspect in the Americas is the inclusion of the United States in the world scenario with 42 reported cases of LC [25].

The overall number of the reported cases of LC is much higher than those of LV, i.e., 66,983of LC in comparison to only 3,668 of LV in the American subcontinent.

Specifically in Brazil, and mostly in other developing countries, leishmaniasis was restricted to rural areas; however, currently the disease has advanced to other regions and has reached urban peripheries [26-28]. This demonstrates that the urbanization process is one of the major factors for the scattering of leishmaniasis.


**Table 4.** Geographical distribution of LV and LC in the Americas, based on references [3], [19] and [25].

The geographical distribution of leishmaniasis in the world appears to be changing, firstly, the variation of global climate [25, 29] could be increasing the area of Phlebotomine niches; and secondly, the globalization of economy increases the migration of the people among countries thereby increasing the contact of people with Phlebotomine niche where leishmaniasis is either incipient or non-existent. The former hypothesis could be explained by the growing economy in BRIC countries, such as Brazil, Russia, India and China; among these India and Brazil are endemic to leishmaniasis.

Nowadays, the geographical distribution of leishmaniasis is similar for LC and LV in the continents; however, differences exist among the countries. Indeed, approximately 57% of countries studied here showed both LC and LV. Nevertheless, in the last ten years the number of the reported LV cases in the world is approximately 58,413 with 77.2% in Asia. In contrast, the number of the reported LC cases in the world is approximately 214,082 with almost 40% of those in the Mediterranean region.

In fact, the reported LC cases are much higher than those reported for LV. A possible explan‐ ation for this scenario is the number of LC parasites, there are over 20 parasites causing LC whereas only just few parasites cause LV. Although there are only few sand fly species that are vectors for both LV and LC, both conditions have the same kind of reservoir hosts [30].

The above problems that have emerged from studying the worldwide geographical distribu‐ tion must be resolved with the collaborative prevention measures by the countries where leishmaniasis is endemic; such cumulative force would lead to the global solutions to eradicate this disease.

#### **3.2. Regional variables**

Regional variables represent areas of the countries where the probability of existence of leishmaniasis has increased. In fact, there are internal regions in different countries such as the rural zone and the urban periphery where the incidence of leishmaniasis has increased (figure 6). A plausible explanation for such increase is the higher density of Phlebotomine and natural reservoir hosts of the parasites inhabiting these areas; these areas in the developing countries are infused with poverty where people live and work close to the forests or the woodlands.

In the developing countries, leishmaniasis was a rural disease, however, it was found to be associated with the growing urbanization. This disease began to develop in the urban periph‐ ery in Brazil and it was noted around 1970s [31]. A probably explanation of such spreading is the internal migration of the people from the rural zone to the urban areas [30].

People that arrive from the rural zones to the urban areas usually have limited and scant financial resources and therefore, they inhabit the periphery of the towns that are regions with the woodland and he forest remnants; they are basically inter topical zones. Such city periphery is a risk zone for the dissemination of leishmaniasis since here the contact among humans, Phlebotomine and their hosts is maximized. Indeed, some reservoir hosts are used as the pets and others are raised in peridomicile to feed these people.

This regional geographical distribution of leishmaniasis incidence must be analyzed by public health agencies to identify and verify the risk zone for leishmaniasis. Additional studies are also required to identify all the causative factors; specifically the data on Phlebotomine niches, presence of natural reservoir hosts of *Leishmania* and the sanitary quality of the habitat for the people are of utmost importance.

The geographical distribution of leishmaniasis in the world appears to be changing, firstly, the variation of global climate [25, 29] could be increasing the area of Phlebotomine niches; and secondly, the globalization of economy increases the migration of the people among countries thereby increasing the contact of people with Phlebotomine niche where leishmaniasis is either incipient or non-existent. The former hypothesis could be explained by the growing economy in BRIC countries, such as Brazil, Russia, India and China; among these India and Brazil are

Nowadays, the geographical distribution of leishmaniasis is similar for LC and LV in the continents; however, differences exist among the countries. Indeed, approximately 57% of countries studied here showed both LC and LV. Nevertheless, in the last ten years the number of the reported LV cases in the world is approximately 58,413 with 77.2% in Asia. In contrast, the number of the reported LC cases in the world is approximately 214,082 with almost 40%

In fact, the reported LC cases are much higher than those reported for LV. A possible explan‐ ation for this scenario is the number of LC parasites, there are over 20 parasites causing LC whereas only just few parasites cause LV. Although there are only few sand fly species that are vectors for both LV and LC, both conditions have the same kind of reservoir hosts [30].

The above problems that have emerged from studying the worldwide geographical distribu‐ tion must be resolved with the collaborative prevention measures by the countries where leishmaniasis is endemic; such cumulative force would lead to the global solutions to eradicate

Regional variables represent areas of the countries where the probability of existence of leishmaniasis has increased. In fact, there are internal regions in different countries such as the rural zone and the urban periphery where the incidence of leishmaniasis has increased (figure 6). A plausible explanation for such increase is the higher density of Phlebotomine and natural reservoir hosts of the parasites inhabiting these areas; these areas in the developing countries are infused with poverty where people live and work close to the forests or the woodlands.

In the developing countries, leishmaniasis was a rural disease, however, it was found to be associated with the growing urbanization. This disease began to develop in the urban periph‐ ery in Brazil and it was noted around 1970s [31]. A probably explanation of such spreading is

People that arrive from the rural zones to the urban areas usually have limited and scant financial resources and therefore, they inhabit the periphery of the towns that are regions with the woodland and he forest remnants; they are basically inter topical zones. Such city periphery is a risk zone for the dissemination of leishmaniasis since here the contact among humans, Phlebotomine and their hosts is maximized. Indeed, some reservoir hosts are used as the pets

the internal migration of the people from the rural zone to the urban areas [30].

and others are raised in peridomicile to feed these people.

endemic to leishmaniasis.

this disease.

**3.2. Regional variables**

of those in the Mediterranean region.

114 Leishmaniasis - Trends in Epidemiology, Diagnosis and Treatment

**Figure 5.** The map of city of Palmas, northern Brazil, is shown. On the left the dots represent reported cases fo leish‐ maniasis in this municipality from 2007 to 2012. The Kernel map of the same locality is demonstrated on the right, where darker/stronger color indicates the higher number of cases. The bigger dots (left) and the dark color distribu‐ tion (right) are present in periphery of the town, that is closest to the forest.

Briefly, the geographical areas of leishmaniasis dissemination are the rural zones and the urban peripheries.

In geographical and regional terms the best way to start the fight against this disease, is the construction of a risk map for each municipality where leishmaniasis is endemic; it will indicate the points where the eradication effort should be focused. Such approach would include the elimination of Phlebotomine along with the complete removal and killing of the natural reservoir hosts of *Leishmania* from the population. We shall not address these specific problems in this chapter, however, georeferencing studies using adequate maps such as Kernel maps (figure 5), utilizing the new technologies for geographical representation along with spatial analysis of databases [32] appear to be the principle strategies to combat leishmaniasis.

Leishmaniasis is a complex multi-systemic disease [33], and therefore, it requires multidisci‐ plinary team effort of public health agencies working together with the health professionals and the scientists to generate the most positive results towards its eradication.

Specifically as regards to the topic of this chapter, the monitoring of the reported cases from the data is an important tool on the geographical variables to control leishmaniasis since it may spread by the internal migration of the people to endemic areas and increasing its incidence due to elevated person-to-person transmission in the crowded living conditions [32].

The analysis of the geographical region is the first step to monitor leishmaniasis, however, majority of causes for endemic outbreak are associated with the natural environment as well as man-made factors such as the human migration, the deforestation, the urbanization and the malnutrition [34].
