Biology subjects

Maia, C.

Publications and source records attributed to Maia, C..

4 recordsLinked to original sources

bioRxiv2026

A systematic review and meta-analysis of risk factors for Leishmania infection in dogs in Europe

BackgroundIdentifying risk factors for Leishmania infection in dogs is essential for understanding disease epidemiology and informing control and targeted prevention. This systematic review and meta-analysis examined these risk factors across endemic and non-endemic regions of Europe. MethodsInclusion criteria included studies that quantified the association between Leishmania infection (both asymptomatic infection and canine leishmaniosis) and risk factors among European dogs. Non-peer reviewed grey literature and studies that focus only on prevention were excluded. The search included all records indexed in PubMed up to 17th March 2026. Risk of bias was assessed using the ROBINS-E tool. Random-effects multilevel models were used for meta-analysis, and sensitivity analyses were conducted to assess robustness. ResultsOf the 46 studies included, 94% were cross-sectional and 76% assessed seroprevalence. Studies were primarily conducted in Southern Europe (Spain 35%, Portugal 17%, Italy 17%, and Greece 11%). There was considerable evidence of an association between increasing age and infection (OR = 1.15 [95% CI: 1.10, 1.21] per year). Five additional factors showed some evidence of association: male sex (OR = 1.17 [1.01, 1.36]), higher body weight (OR = 1.06 [1.02, 1.09] per kg), outdoor housing (OR = 1.84 [1.26, 2.69]), outdoor sleeping (OR = 2.50 [1.52, 4.09]), and neuter status showing higher odds in neutered dogs (OR = 2.22 [1.37, 3.61]). Other potential risk factors, with weak or no clear evidence, included fur length, coat color, breed, utilization (e.g. pet or hunting), urbanicity, care setting, clinical signs, cohabitation, co-infection, sand fly density, land cover, home features, owner perception and knowledge of the disease, travel history and origin of dog, and area-level socioeconomic deprivation. Over 75% of analytical units were assessed as having a high risk of bias, with the remaining assessed as moderate risk. Inadequate handling of confounders was the primary source of bias risk. ConclusionsThe results highlight key risk factors to consider in future research and for improving prevention and disease control, with most identified factors likely acting as proxies of exposure to sand fly bites. Future studies should ensure adequate control for confounding, while causal inference would be strengthened by conducting longitudinal cohort studies.

zoology↗

bioRxiv2026

A single-stranded DNA virus replicates in the mitochondria of a marine oomycete

A virus with a circular single-stranded DNA genome, HthCRESSV1, was discovered in an oomycete, Halophytophthora thermoambigua, isolated from brackish waters off the Algarve coast in southern Portugal. Phylogenetic analyses place this virus outside of all currently classified families within the phylum Cressdnaviricota, suggesting it represents a distinct lineage. Cellular fractionation, mitochondrial marker co-enrichment, and Southern blot analyses indicate that HthCRESSV1 is associated with mitochondria and replicates episomally. The virus is stably transmitted through zoospores and, notably, infected host isolates are associated with reduced growth and changes in temperature-dependent performance. Homologous sequences corresponding to both the replication-associated protein and a membrane-associated hypothetical protein were identified in the mitochondrial genomes of several oomycete species, suggesting recurrent endogenization of HthCRESSV1-like viruses in oomycete mitochondria. Together, these findings expand the known diversity of oomycete-associated DNA viruses, identify mitochondria as an unexpected niche for DNA virus replication, and highlight marine environments as underexplored reservoirs of DNA viruses in stramenopiles.

evolutionary biology↗

bioRxiv2025

Drug-Resistance Biomarkers in Leishmania infantum through Nanopore-Based Detection of Aneuploidy and Gene Copy Number Variations with LeishGenApp

BackgroundDrug-resistant strains of Leishmania infantum challenge the effectiveness of treatments for clinical leishmaniosis and may lead to more frequent relapses. Copy number variation (CNV) at specific genetic loci is associated with drug resistance and virulence, but information about its prevalence in endemic regions is limited. This study examines the drug resistance and virulence status of Leishmania strains in human and canine isolates from the Mediterranean region. MethodsForty-eight Leishmania infantum isolates were whole-genome sequenced with nanopore long reads, followed by de novo assembly. We analyzed chromosomal aneuploidies and gene copy number variation in loci linked to drug resistance and virulence in Leishmania, alongside the genomic structure and rearrangements responsible for these variations. ResultsComplete genomes were de novo assembled for 35 L. infantum isolates (22 from dogs and 13 from humans), revealing significant chromosomal variability. We assessed copy number variation for 22 potential biomarkers: 15 genes related to drug resistance to first-line drugs (METK for allopurinol; LdSMT for amphotericin B; AQP1 and H-locus for antimonials; LdMT, LdRos3, and MSL for miltefosine; PPM for paramomycin) and seven genes related to virulence (lipophosphoglycan and proteophosphoglycan biosynthesis, and the Lack protein). Drug-resistance biomarkers were identified in 80% of the isolates. Canine strains primarily showed resistance to allopurinol and antimonials, while human isolates exhibited a broader resistance spectrum, especially to antimonials and paromomycin. The co-occurrence of resistance biomarkers was common, especially for allopurinol and antimonial resistance. Distinct mechanisms underlie the observed copy number variations. Virulence-associated genes were less variable among isolates. ConclusionsThe prevalence of drug-resistance biomarkers in Leishmania infantum strains from the Mediterranean region, as revealed by this study, underscores the critical need for routine resistance surveillance in managing clinical leishmaniosis. These findings not only inform current clinical practice but also pave the way for more effective management strategies in the future.

genetics↗

bioRxiv2023

Phylogenetics, Epidemiology and Temporal Patterns of Dengue Virus type 1 in Araraquara, Sao Paulo State

Dengue virus is a prominent arbovirus with global spread, causing approximately 390 million infections each year. In Brazil, yearly epidemics follow a well-documented pattern of serotype replacement every three to four years on average. Araraquara, located in the state of Sao Paulo, has faced significant impacts from DENV epidemics since the emergence of DENV-1 in 2010. The municipality then transitioned from low to moderate endemicity in less than 10 years. Yet, there remains an insufficient understanding of the virus circulation dynamics, particularly concerning DENV-1, in the region, as well as the genetic characteristics of the virus. To address this, we generated 37 complete or partial DENV-1 genomes sampled from 2015 to 2022 in Araraquara. Then, using also Brazilian and worldwide DENV-1 sequences we reconstructed the evolutionary history of DENV-1 in Araraquara and estimated the time to the most recent common ancestor (tMRCA) for the serotype 1, for the genotype V and its main lineages. Within the last ten years, there were at least three introductions of genotype V in Araraquara, distributed in the two main lineages (LIa and LIb, and LII). The tMRCA for the first sampled lineage (2015/2016 epidemics) was approximately 15 years ago (in 2008). Crucially, our analysis challenges existing assumptions regarding emergence time of the DENV-1 genotypes, suggesting that genotype V might have diverged more recently than previously described. The presence of the two lineages of genotype V in the municipality might have contributed to the extended persistence of DENV-1 in the region.

genomics↗