GHTM research unveils parasite–host interactions, explores the role of cats and dogs in leishmaniasis and tracks emerging sand fly vectors transmission across Europe.
On the occasion of World Neglected Tropical Diseases (NTD) Day, we recognize the ongoing challenges posed by diseases that disproportionately affect the world’s most vulnerable populations. Leishmaniasis, a neglected tropical disease, remains a major public health concern, causing significant human and animal suffering while receiving comparatively little attention and resources. GHTM | IHMT NOVA is committed to advancing research and One Health approaches that improve understanding, prevention, and control of these diseases.
Leishmaniasis: A Neglected Tropical Disease
Leishmaniasis is a neglected tropical disease affecting some of the world’s poorest populations. Linked to malnutrition, displacement, poor housing, weakened immunity, and limited resources, the disease remains a major public health challenge, as highlighted by the World Health Organization (WHO). In Europe, human visceral and cutaneous leishmaniasis caused by Leishmania infantum is endemic in southern countries, where dogs serve as the main hosts and reservoirs. Transmission occurs through bites from Phlebotomus (Larroussius) sand fly species, whose range, traditionally confined to Mediterranean regions, is now expanding northwards due to climate change and human activities, creating new hotspots for infection.
The Role of Dogs and Parasite–Host Communications
Dogs are the primary domestic reservoir of Leishmania parasites, playing a key role in parasite maintenance within communities due to their close contact with humans. Infection begins in the skin when parasites are inoculated during a sand fly’s blood meal. From there, critical events unfold as parasites interact with skin and immune cells, such as macrophages and dendritic cells, modulating the host immune response to ensure survival, replication, and persistence.
The miL3DSkin project (“New approaches on neglected cutaneous Leishmaniasis: tridimensional (3D) skin models and miRNA signatures”), funded by the Fundação para a Ciência e Tecnologia (FCT) and coordinated by Armanda Rodrigues, researcher from VBD-GHTM Research Group, is exploring this first encounter between parasite and canine host. By combining advanced 3D skin culture models with molecular biology, a multidisciplinary team of researchers and students from national and international institutions is uncovering how Leishmania parasites and parasite-derived extracellular vesicles (EVs) communicate with the host and influence gene regulation via microRNAs. Embedding a One Health vision, these insights could lead to better diagnostics and treatments, improving animal wellbeing.
Tracking Emerging Vectors: The CLIMOS Project
To address emerging risks, the CLIMOS project, a 45-month Horizon Europe initiative led by GHTM | IHMT-NOVA and coordinated by Carla Maia, researcher from the VBD-GHTM Research Group, brings together 29 partners from 16 countries to develop an Early Warning System (EWS). The system forecasts shifts in sand fly distribution and activity, assesses transmission risks and socioeconomic burdens of fly-borne diseases, and provides evidence-based policy advice through One Health strategies.
During the 2023–2024 trapping seasons across 12 countries, over 96,000 sand fly specimens from 26 taxa were collected, dominated by Larroussius species such as P. perniciosus, P. perfiliewi, and P. tobbi. Notably, CLIMOS recorded P. perfiliewi for the first time in Slovenia, extending this key vector’s range in the Balkans, while experimental studies confirmed the vectorial competence of P. mascittii—Europe’s northernmost and most widely distributed sand fly—for L. infantum. The project also confirmed that P. perfiliewi can support the development of L. tropica (endemic in the Eastern Mediterranean, Middle East, North Africa, and parts of South Asia) and L. major (endemic across North Africa, the Middle East, Central Asia, and West Asia), species responsible for cutaneous leishmaniasis outside Europe, raising concerns about the introduction of exotic species to new areas. Climate projections using machine-learning and ecological niche models further highlight future shifts in sand fly distribution across the continent, with moisture identified as a key driver.
Some findings are already available in Parasites & Vectors' dedicated CLIMOS collection.
Expanding the Focus: Cats as Potential Hosts
While dogs remain the main reservoir, recent evidence indicates that cats may also play a role in maintaining Leishmania infantum in domestic environments. Previous GHTM research developed by Carla Maia and her team has shown that cats are frequently exposed to the parasite, can develop clinical disease, are bitten by sand flies, and may carry parasites genetically identical to those found in dogs, humans, and vectors. This suggests that cats may share the same transmission cycle and that infected cats could potentially pass the parasite on to sand flies, contributing to its spread.
To better understand feline leishmaniasis in Portugal, GHTM researchers are conducting:
- A nationwide survey of domestic cats in collaboration with Universidade Lusófona and DNATech to estimate seroprevalence.
- A study characterizing clinical occurrence of feline leishmaniasis, engaging veterinarians who have diagnosed or observed cases of feline leishmaniasis to better understand how the diagnosis, treatment, and prevention of this zoonosis are being addressed in cats in Portugal.
These studies help clarify the role of cats in transmission cycles, supporting more effective One Health strategies.
Towards Better Control and Prevention
From decoding parasite–host communication in dogs to tracking emerging vectors across Europe, and explore the role of cats in leishmaniasis transmission, GHTM research combines cutting-edge science with a One Health perspective. By integrating molecular biology, epidemiology, and veterinary science, our work contributes to improved diagnostics, treatments, and early warning systems, ultimately reducing the burden of leishmaniasis for humans and animals alike.
This article is published as part of the World Neglected Tropical Diseases (NTD) Day celebrations. To learn more about our work on neglected tropical diseases, see our related news:
World Neglected Tropical Diseases Day: Advancing Research to Leave No One Behind
Advancing Research on Helminth Neglected Tropical Diseases at GHTM
Sleeping Sickness: GHTM Research and Response on World Neglected Tropical Diseases Day
[…] World NTD Day: Decoding Leishmania from Dogs to Emerging European Vectors […]