Biology subjects

Calzolari, M.

Publications and source records attributed to Calzolari, M..

4 recordsLinked to original sources

bioRxiv2026

Multilocus microsatellite typing (MLMT) reveals high genetic diversity of Leishmania infantum strains causing tegumentary leishmaniasis in northern Italy

BackgroundTegumentary leishmaniasis (TL) caused by Leishmania infantum has re-emerged in northern Italy, raising questions about the genetic diversity and population structure of circulating parasites and their potential role in shaping different clinical outcomes. Methodology/Principal findingsMultilocus microsatellite typing (MLMT) based on 15 polymorphic loci was applied to 44 L. infantum strains obtained from TL cases diagnosed between 2013 and 2024 in the Emilia-Romagna region. These strains were compared with sympatric isolates from VL cases, dogs and sand flies. MLMT revealed a considerable genetic variation among TL-associated strains, with 43 distinct multilocus genotypes identified. Population structure analyses using Bayesian clustering, multivariate approaches and phylogenetic reconstruction consistently identified three highly differentiated genetic populations (Fst >0.25). TL strains were divided into two main populations: one shared with VL-associated strains (PopB; 9/44) and a second population found exclusively among TL cases (PopC; 28/44). In contrast, the canine-associated population (PopA) showed no overlap with TL cases in this region. Populations also displayed divergent heterozygosity patterns, as indicated by positive and negative Fis values. Conclusions/SignificanceThese findings revealed previously unknown diversity within L. infantum in the study area and demonstrated that inclusion of tegumentary strains is essential to uncover hidden components of parasite population structure. The identification of a TL-associated population supports the existence of multiple evolutionary pathways and emphasises the importance of integrated One Health surveillance, which combines data from humans, animal hosts and vectors to improve understanding of the epidemiology of leishmaniasis in Italy. Author summaryLeishmania infantum is a parasite transmitted to humans through the bite of infected insect vectors. It can cause different forms of leishmaniasis, ranging from a systemic disease known as visceral leishmaniasis to a less common form that affects the skin and mucous membranes, called tegumentary leishmaniasis. Dogs are the main reservoir of the parasite and play a key role in maintaining its circulation in endemic areas. In recent years, cases of tegumentary leishmaniasis have re-emerged in northern Italy. This unexpected increase has raised questions about how the parasite is spreading and whether genetic differences among the parasites could explain these new patterns. To explore this, we examined parasitic DNA obtained from tegumentary leishmaniasis cases and compared it with DNA from patients with visceral leishmaniasis, from dogs and insect vectors from the same area. By examining multiple genetic markers, we found that parasites causing the tegumentary form of the disease are genetically diverse and belong to different groups. Notably, one parasite group was found only in cases of tegumentary leishmaniasis and not in visceral infections nor in infected dogs, suggesting that some parasite lineages may be more closely associated with skin and mucosal disease. Overall, our findings show that studying parasites from cutaneous and mucosal lesions provides important information that would otherwise remain hidden. By combining data from humans, animals and insect vectors, our study highlights the importance of integrated surveillance systems for improving our understanding of disease spread and supporting effective public health strategies.

genetics↗

bioRxiv2025

Association of avian biodiversity and West Nile virus circulation in Culex mosquitoes in Emilia-Romagna, Italy

West Nile Virus (WNV) is a zoonotic arbovirus maintained in a transmission cycle between Culex mosquitoes and birds, occasionally spilling over into humans. The impact of avian biodiversity on WNV circulation remains debated, with studies reporting both negative and positive correlations (dilution and amplification effects respectively) across different settings. In Europe, this relationship remains largely unexplored, particularly in regions with high WNV transmission, such as Emilia-Romagna in Northern Italy. We explored the association between avian biodiversity and WNV circulation in Culex mosquitoes in Emilia-Romagna using 11 consecutive years (2013-2023) of entomological surveillance data paired with two avian data sources. We calculated avian biodiversity indices (Shannons, Simpsons, and Chao2) from observation records from the Farmland Bird Index project and applied linear regression models to assess their relationship with WNV circulation levels. Moreover, we used Bayesian spatiotemporal regression models and gridded weekly avian abundance estimates from the eBird project, to analyse the associations between avian species richness indices and WNV-positivity rates at 68 geolocated mosquito traps across the region. We observed consistent negative associations between WNV circulation in the Culex population and avian biodiversity indices, supporting the dilution effect hypothesis (DEH). We found that non-passerine species richness was negatively associated with WNV mosquito circulation, whereas passerine species richness exhibited a positive association after adjusting for environmental factors and spatial random effects. These findings suggest that passerines may amplify WNV transmission, while the presence of non-passerine species is associated with reductions in WNV circulation. This study provides the first empirical evidence supporting the DEH for WNV in Europe. These findings have important implications for avian surveillance and future WNV modelling studies, and can inform regional, national and European policies on biodiversity conservation and public health planning. Author summaryWest Nile Virus (WNV) is a zoonotic, vector-borne disease maintained in a mosquito-bird-mosquito transmission cycle. The role of avian biodiversity in WNV transmission remains debated, with studies reporting both dilution effects (negative associations) and amplification effects (positive associations) across different settings. Here, we examined the impact of avian biodiversity on WNV circulation in Culex mosquitoes in Emilia-Romagna, Italy, one of Europes WNV hotspots. We analysed 11 years (2013-2023) of entomological surveillance data alongside two ornithological datasets, respectively collected by the Farmland Bird Index project and the citizen science project eBird. These different datasets allowed us to test the dilution effect hypothesis (DEH) at broad and fine spatiotemporal resolutions. Our findings provide support for the DEH for WNV, revealing that higher bird community diversity is associated with reduced WNV circulation. Additionally, we found that non-passerine species richness is linked to lower levels of WNV circulation in the vector, whereas passerine species richness is positively associated with WNV transmission from entomological surveillance. These results point towards the potential amplifying role of passerine species and the protective role of non-passerine species in WNV transmission dynamics, which has important implications for species conservation, public health policy and future modelling studies.

ecology↗

bioRxiv2023

Genomic and epidemiological evidence for the emergence of a putative L. donovani/L. infantum hybrid with unusual epidemiology in Northern Italy

Leishmania (L.) infantum is the main causative agent of animal and human leishmaniasis in the Mediterranean basin. Despite its clinical significance, little is known on the genetic diversity of L. infantum parasites circulating in Italy. Here, we apply a comparative genomics approach on seven L. infantum isolates from different hosts (human, dog, cat, marten) and geographic regions (Emilia-Romagna, Sicily, Sardinia) as a first attempt to explore the breadth of parasite genetic heterogeneity in Italy. We revealed important genome instability at karyotype levels, with each isolate presenting a unique aneuploidy profile. Read depth analysis further identified strain-specific changes in gene dosage, which affected important virulence factors most of which are encoded by multi-copy gene arrays, such as amastins or surface antigen-like proteins. SNP-based clustering analysis of these genomes together with over 80 publicly available L. infantum and L. donovani genomes placed the Italian isolates into three geographically distinct clusters, with two isolates grouping with Spanish strains, two isolates grouping with Tunisian strains, and three isolates clustering with putative L. infantum/L. donovani hybrids isolated in Cyprus. As judged by microsatellite profiling of 73 isolates from dogs, sand flies and VL cases, these hybrid isolates are representative of a sub-population of parasites circulating in northeastern Italy that preferentially infects humans, but not dogs. In conclusion, our data uncover a remarkable heterogeneity of L. infantum isolates that indicates different geographic origin, including a novel hybrid-like genotype associated with an unusual infection pattern, placing Italy at the crossroad of Leishmania infection in the Mediterranean region.

genomics↗

bioRxiv2020

Mosquitoes of the Maculipennis complex in Northern Italy

The correct identification of mosquito vectors is often hampered by the presence of morphologically indiscernible sibling species. The Maculipennis complex is one of these groups which include both malaria vectors of primary importance and species of low/negligible epidemiological relevance, of which distribution data in Italy are outdated. Our study was aimed at providing an updated distribution of Maculipennis complex in Northern Italy through the sampling and morphological/molecular identification of specimens from five regions. The most abundant species was Anopheles messeae s.l. (2032), followed by Anopheles maculipennis s.s. (418), Anopheles atroparvus (28) and Anopheles melanoon (13). The distribution of species was characterized by Ecological Niche Models (ENMs), fed by recorded points of presence. ENMs provided clues on the ecological preferences of the detected species, with An. messeae s.l. linked to stable breeding sites and An. maculipennis s.s. more associated to ephemeral breeding sites. We demonstrate that historical Anopheles malaria vectors are still widespread in Northern Italy.

ecology↗