Ecological niche modelling and predicted geographic distribution of Lutzomyia cruzi, vector of Leishmania infantum in South America

Abstract

In some transmission foci of Leishmania infantum in Brazil, Lutzomyia cruzi could be considered the main vector of this pathogen. In addition, L. cruzi is a permissive vector of L. amazonensis. Its geographical distribution seems to be restricted and limited to Cerrado and Pantanal biomes, which includes some areas in Brazil and Bolivia. Considering that predicting the distribution of the species involved in transmission cycles is an effective approach for assessing human disease risk, this study aims to predict the spatial distribution of L. cruzi using a multiscale ecological niche model based in both climate and habitat variables. Ecological niche modelling was used to identify areas in South America that are environmentally suitable for this particular vector species, but its presence is not recorded. Vector occurrence records were compiled from the literature, museum collections and Brazilian Health Departments. Bioclimatic variables, altitude, and land use and cover were used as predictors in five ecological niche model algorithms: BIOCLIM, generalised linear model (logistic regression), maximum entropy, random forests, and support vector machines. The vector occurs in areas where annual mean temperature values range from 21.76°C to 26.58°C, and annual total precipitation varies from 1005 mm and 2048 mm. Urban areas were most present around capture locations. The potential distribution area of L. cruzi according to the final ecological niche model spans Brazil and Bolivia in patches of suitable habitats inside a larger climatically favourable area. The bigger portion of this suitable area is located at Brazilian States of Mato Grosso do Sul and Mato Grosso. Our findings identified environmentally suitable areas for L. cruzi in regions without its known occurrence, so further field sampling of sand flies is recommended, especially in southern Goiás State, Mato Grosso do Sul (borders with Mato Grosso, São Paulo and Minas Gerais); and in Bolivian departments Santa Cruz and El Beni.

Assessing geographic and climatic variables to predict the potential distribution of the visceral leishmaniasis vector Lutzomyia longipalpis in the state of Espírito Santo, Brazil

“…In Brazil, the municipality of Itapira, located in the state of São Paulo (SP), was the focus of an SDM study for predicting a risk area for the spread of cutaneous leishmaniasis [ 36 ], whereas environmental niches for VL were studied in the state of Bahia (BA) [ 37 ]. VL risk areas were also investigated in the Brazilian states of Piauí [ 38 ], Mato Grosso do Sul [ 39 , 40 ], Minas Gerais (MG) [ 41 ], and Rio de Janeiro (RJ) [ 42 ]. In ES, Meneguzzi et al (2016), using SDM, investigated the association between cutaneous leishmaniasis cases and five sandfly vectors, with Lutzomyia intermedia considered the main vector in the state for its strongest associations with disease cases [ 43 ].…”

Visceral Leishmaniasis in Bolivia: Current Status

“…longipalpis include Lu. cruzi 13 , 14 and less related species that have adapted to environments with anthropic modifications, such as Migonemyia migonei 15 , 16 , can act as L. infantum vectors in VL areas where Lu. longipalpis is not present, or in scenarios in which two or more species display sympatric presence.…”

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“…Unfortunately, regardless of its global prevalence and devastating impact on the lives of millions of individuals, the disease is still considered as neglected tropical disease, mainly affecting underprivileged communities, associated with poor economic conditions, inadequate access to shelter, healthcare and medication 2 . Sudden outbreak and the spread of the disease is associated with the changes in environmental conditions which is making more prone ambience for the growth of sand-fly vector, while the emigration of the people into the endemic areas are increasing the risk of mass individuals 3 . With passing time, the reservoir of the disease is increasing, and the major concern related to this disease is its co-occurrence with HIV 4 .…”