Map of Brazil highlighting areas with high Leishmaniasis risk.

Silent Spreaders: Mapping the Risk of Leishmaniasis in Brazil

Kai Mendoza in Health & Wellness December 2025 • 4 min read.

"New research unveils the distribution of sand flies carrying Leishmania, offering insights for targeted prevention and control in high-risk areas."

Leishmaniases are a group of diseases caused by protozoan parasites transmitted through the bite of infected phlebotomine sand flies. Visceral leishmaniasis (VL), the most severe form, is particularly concerning due to its potential fatality if left untreated. Brazil faces a significant burden of VL, especially in urban centers.

Understanding the distribution of these sand fly vectors is crucial for effective disease control. With approximately 270 sand fly species identified in Brazil, their presence is closely tied to specific ecosystems and ecological niches. Some species, like Lutzomyia longipalpis, are widespread and adaptable, while others, such as Lutzomyia cruzi, have a more restricted geographical range. Both are key vectors of Leishmania infantum, the parasite responsible for VL in Brazil.

To better understand and predict the spread of VL, researchers combined data from various sources, including sand fly collections, scientific literature, and disease surveillance systems. Using ecological niche modeling, they created occurrence probability maps for Lu. longipalpis and Lu. cruzi, identifying areas where these vectors are most likely to be present. This information is vital for implementing targeted surveillance and control measures.

Unveiling Sand Fly Hotspots: Data and Methods

Map of Brazil highlighting areas with high Leishmaniasis risk.

The study compiled occurrence records for Lu. longipalpis and Lu. cruzi from multiple sources:

Researchers also incorporated data on autochthonous (locally acquired) cases of visceral leishmaniasis from the Brazilian Ministry of Health's Notifiable Diseases Information System (SINAN/MS) from 2004-2016.

The sand fly collection of the Oswaldo Cruz Foundation (FIOCRUZ-COLFLEB).
The SpeciesLink database.
Systematic reviews of scientific articles, theses, and communications.

To map the potential distribution of the sand flies, the study used MaxEnt, an ecological niche modeling software, combined with environmental and climatic data. Key environmental variables included elevation, land surface temperature, vegetation index, and various climate factors like temperature and precipitation. The accuracy of the model was assessed using the Area Under the Curve (AUC) statistic, with values closer to 1 indicating higher predictive performance.

Implications for Disease Control

The study found Lu. longipalpis present in 229 Brazilian municipalities and Lu. cruzi in 27, with co-occurrence in 16 municipalities in the Central-West region. The widespread distribution of Lu. longipalpis aligns with the high number of VL cases reported in Brazil.

The predictive maps highlight areas where Lu. longipalpis and Lu. cruzi are likely to be present, even in regions where they haven't been explicitly recorded. This information is critical for guiding surveillance efforts and implementing targeted control measures, such as insecticide spraying or environmental management.

By identifying high-risk areas, public health officials can allocate resources more effectively, focusing on regions where interventions will have the greatest impact. The study provides a valuable tool for proactive disease management, contributing to the reduction of VL incidence in Brazil.

About this Article -

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This article is based on research published under:

DOI-LINK: 10.1093/jme/tjx094, Alternate LINK

Title: Occurrence And Probability Maps Of Lutzomyia Longipalpis And Lutzomyia Cruzi (Diptera: Psychodidae: Phlebotominae) In Brazil

Subject: Infectious Diseases

Journal: Journal of Medical Entomology

Publisher: Oxford University Press (OUP)

Authors: J. D. Andrade-Filho, R.G.C. Scholte, A.L.G. Amaral, P.H.F. Shimabukuro, O. S. Carvalho, R. L. Caldeira

Published: 2017-05-04

Everything You Need To Know

What causes Leishmaniasis, and which specific species are the main carriers in Brazil?

Leishmaniasis is caused by protozoan parasites transmitted through the bite of infected phlebotomine sand flies. Visceral leishmaniasis (VL), the most severe form, is of particular concern in Brazil due to its potential fatality if left untreated. The key vectors in Brazil are Lutzomyia longipalpis and Lutzomyia cruzi, which transmit Leishmania infantum, the parasite responsible for VL. Other forms of Leishmaniasis exist, such as cutaneous leishmaniasis, but Visceral leishmaniasis is the primary focus due to its severity.

How did the researchers map the distribution of the sand flies Lutzomyia longipalpis and Lutzomyia cruzi?

The study utilized ecological niche modeling, specifically employing MaxEnt software, to predict the distribution of Lutzomyia longipalpis and Lutzomyia cruzi. Researchers integrated data from sand fly collections (FIOCRUZ-COLFLEB), the SpeciesLink database, scientific literature, and autochthonous cases of visceral leishmaniasis from Brazil's Notifiable Diseases Information System (SINAN/MS). Environmental variables such as elevation, land surface temperature, vegetation index, and climate factors were incorporated into the model. The accuracy of the model was assessed using the Area Under the Curve (AUC) statistic.

What were the key findings regarding the distribution of Lutzomyia longipalpis and Lutzomyia cruzi across Brazilian municipalities?

The study identified that Lutzomyia longipalpis is present in 229 Brazilian municipalities, while Lutzomyia cruzi is found in 27. Sixteen municipalities in the Central-West region showed co-occurrence of both species. The widespread distribution of Lutzomyia longipalpis is consistent with the high number of VL cases reported throughout Brazil. This information helps to target surveillance and control measures more effectively.

What are the practical implications of knowing where Lutzomyia longipalpis and Lutzomyia cruzi are most prevalent?

Understanding the geographical distribution of Lutzomyia longipalpis and Lutzomyia cruzi allows for targeted public health interventions. By identifying high-risk zones, resources can be allocated efficiently for surveillance, vector control (such as insecticide spraying), and early diagnosis and treatment of Visceral Leishmaniasis. This targeted approach can reduce the burden of VL in affected communities. Further research could explore the effectiveness of different control strategies in these identified hotspots.

What aspects of Leishmaniasis and its spread weren't addressed, and what further research could improve our understanding and control efforts?

While the study successfully mapped the distribution of Lutzomyia longipalpis and Lutzomyia cruzi, it primarily focused on environmental and climatic factors. Future studies could incorporate socioeconomic data, such as poverty levels and access to healthcare, to further refine the risk assessment. Additionally, exploring the genetic diversity of Leishmania infantum and its impact on disease severity could provide valuable insights for developing more effective treatment strategies. Research into novel vector control methods, beyond traditional insecticide use, is also warranted.