Functionalized bioadhesion-enhanced carboxymethyl cellulose/polyvinyl alcohol hybrid hydrogels for chronic wound dressing applications.

Wounds produced by trauma, burns, and chronic diseases cause millions of patients to suffer discomfort, pain, and, in many cases, disability and death, leading to enormous health, social and financial impacts globally. Regrettably, current clinical treatments for chronic wounds remain unsatisfactory. Thus, this study reports for the first time the design, development, and synthesis of chemically biofunctionalized hybrid hydrogels made of carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) crosslinked by citric acid using an entirely biocompatible and green process. They demonstrated suitable physicochemical properties, cytocompatibility, and hemocompatibility to be applied as a smart wound dressing for skin tissue engineering. These novel hybrids were biofunctionalized with l-arginine and RGD peptide through carbodiimide mediated-amide formation to promote bioadhesion of fibroblast and keratinocyte cells as a potential enhancement for wound healing and skin tissue engineering applications.

Subcellular localization and interactions among TGB proteins of cowpea mild mottle virus.

Cowpea mild mottle virus (CPMMV) is a flexuous filamentous virus that belongs to the genus Carlavirus (family Betaflexiviridae). The CPMMV genome contains six open reading frames (ORFs), among which the triple gene block (TGB), encoded by ORFs 2 to 4, has been reported to encode movement proteins for different viruses. The subcellular localization of the TGB proteins of CPMMV isolate CPMMV:BR:MG:09:2 was analysed by transient expression of each protein fused to a fluorophore. Overall, the accumulation pattern and interactions among CPMMV TGB proteins (TGBp) were similar to those of their counterparts from the potex-like group. Considering these similarities, we evaluated the potential interactions between the TGB proteins of CPMMV and of potato virus X, which could complement cell-to-cell movement. The TGBp2 and TGBp3 of PVX had an effect on CPMMV TGBp1, directing it to the plasmodesmata, but the reverse was not true.

Inter-annual variability patterns of reef cryptobiota in the central Red Sea across a shelf gradient.

The combination of molecular tools, standard surveying techniques, and long-term monitoring programs are relevant to understanding environmental and ecological changes in coral reef communities. Here we studied temporal variability in cryptobenthic coral reef communities across the continental shelf in the central Red Sea spanning 6 years (three sampling periods: 2013-2019) and including the 2015 mass bleaching event. We used a combination of molecular tools (barcoding and metabarcoding) to assess communities on Autonomous Reef Monitoring Structures (ARMS) as a standardized sampling approach. Community composition associated with ARMS for both methodologies (barcoding and metabarcoding) was statistically different across reefs (shelf position) and time periods. The partition of beta diversity showed a higher turnover and lower nestedness between pre-bleaching and post-bleaching samples than between the two post-bleaching periods, revealing a community shift from the bleaching event. However, a slight return to the pre-bleaching community composition was observed in 2019 suggesting a recovery trajectory. Given the predictions of decreasing time between bleaching events, it is concerning that cryptobenthic communities may not fully recover and communities with new characteristics will emerge. We observed a high turnover among reefs for all time periods, implying a homogenization of the cryptobiome did not occur across the cross shelf following the 2015 bleaching event. It is possible that dispersal limitations and the distinct environmental and benthic structures present across the shelf maintained the heterogeneity in communities among reefs. This study has to the best of our knowledge presented for the first time a temporal aspect into the analysis of ARMS cryptobenthic coral reef communities and encompasses a bleaching event. We show that these structures can detect cryptic changes associated with reef degradation and provides support for these being used as long-term monitoring tools.

Contrasting Effects of Local Environmental and Biogeographic Factors on the Composition and Structure of Bacterial Communities in Arid Monospecific Mangrove Soils.

Mangrove forests are important biotic sinks of atmospheric CO2 and play an integral role in nutrient-cycling and decontamination of coastal waters, thereby mitigating climatic and anthropogenic stressors. These services are primarily regulated by the activity of the soil microbiome. To understand how environmental changes may affect this vital part of the ecosystem, it is key to understand the patterns that drive microbial community assembly in mangrove forest soils. High-throughput amplicon sequencing (16S rRNA) was applied on samples from arid Avicennia marina forests across different spatial scales from local to regional. Alongside conventional analyses of community ecology, microbial co-occurrence networks were assessed to investigate differences in composition and structure of the bacterial community. The bacterial community composition varied more strongly along an intertidal gradient within each mangrove forest, than between forests in different geographic regions (Australia/Saudi Arabia). In contrast, co-occurrence networks differed primarily between geographic regions, illustrating that the structure of the bacterial community is not necessarily linked to its composition. The local diversity in mangrove forest soils may have important implications for the quantification of biogeochemical processes and is important to consider when planning restoration activities. IMPORTANCE Mangrove ecosystems are increasingly being recognized for their potential to sequester atmospheric carbon, thereby mitigating the effects of anthropogenically driven greenhouse gas emissions. The bacterial community in the soils plays an important role in the breakdown and recycling of carbon and other nutrients. To assess and predict changes in carbon storage, it is important to understand how the bacterial community is shaped by its environment. Here, we compared the bacterial communities of mangrove forests on different spatial scales, from local within-forest to biogeographic comparisons. The bacterial community composition differed more between distinct intertidal zones of the same forest than between forests in distant geographic regions. The calculated network structure of theoretically interacting bacteria, however, differed most between the geographic regions. Our findings highlight the importance of local environmental factors in shaping the microbial soil community in mangroves and highlight a disconnect between community composition and structure in microbial soil assemblages.

How is COVID-19 affecting patients with obsessive-compulsive disorder? A longitudinal study on the initial phase of the pandemic in a Spanish cohort.

BACKGROUND: Although the consequences of the COVID-19 pandemic on emotional health are evident, little is known about its impact on patients with obsessive-compulsive disorder (OCD). METHODS: One hundred and twenty-seven patients with OCD who attended a specialist OCD Clinic in Barcelona, Spain, were assessed by phone from April 27 to May 25, 2020, during the early phase of the pandemic, using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) and a structured interview that collected clinical and sociodemographic information. Results were compared with those for 237 healthy controls from the same geographic area who completed an online survey. RESULTS: Although 65.3% of the patients with OCD described a worsening of their symptoms, only 31.4% had Y-BOCS scores that increased >25%. The risk of getting infected by SARS-CoV2 was reported as a new obsession by 44.8%, but this only became the main obsessive concern in approximately 10% of the patients. Suicide-related thoughts were more frequent among the OCD cohort than among healthy controls. The presence of prepandemic depression, higher Y-BOCS scores, contamination/washing symptoms, and lower perceived social support all predicted a significantly increased risk of OCD worsening. CONCLUSIONS: Most patients with OCD appear to be capable of coping with the emotional stress of the COVID-19 outbreak and its consequences during the initial phase of the pandemic. Nevertheless, the current crisis constitutes a risk factor for a significant worsening of symptoms and suicidal ideation. Action is needed to ensure effective and individualized follow-up care for patients with OCD in the COVID-19 era.

MC3T3-E1 cell response to microporous tantalum oxide surfaces enriched with Ca, P and Mg.

The formation of a porous oxide surface doped with osteoconductive elements, Ca, P and Mg, to enhance osseointegration, was achieved through micro arc oxidation. Micro arc oxidation parameters, such as electrolyte composition, concentration and applied voltage, were studied to understand their effect on the morphology and chemical composition of the samples surface. Considering the optimum atomic concentration reported in literature for each osteoconductive element, microporous Ta anodic oxide samples treated with calcium acetate (CaA) and ß-glycerophosphate (ß-GP) revealed that an increase of ß-GP molarity in the electrolyte boosts Ca incorporation, as well as, increasing the porosity. In adding magnesium acetate (MgA) to the electrolyte, when composed by CaA + ß-GP, both addition and variation of MgA did not affect the surface morphology along the samples, being incorporated into the oxide layer for 0.1 M. Finally, in vitro tests were carried out to study the biocompatibility of Ta, to verify the cytotoxicity of the samples and their behavior towards cells, by performing adhesion and differentiation tests with the MC3T3-E1 cell line. Cytotoxicity tests revealed that the samples were non-toxic. Despite none of the samples having been raised up through cell adhesion tests, cell differentiation revealed promising results for the Ta-CaP.

Role of methyl jasmonate and salicylic acid in kiwifruit plants further subjected to Psa infection: biochemical and genetic responses.

The use of plant elicitors for controlling Pseudomonas syringae pv. actinidiae (Psa), the etiological agent of the kiwifruit bacterial canker (KBC), has been analysed in the past and, while salicylic acid (SA) seems to decrease disease susceptibility, methyl jasmonate (MJ) shows an opposite effect. However, the metabolic and genomic responses of Psa-infected plants following elicitation with these two compounds, as compared with non-elicited Psa-inoculated plants, are poorly understood, being the focus of this study. Micropropagated A. chinensis 'Hayward' plants were elicited with MJ or SA, and further inoculated with Psa. Fifteen days post-inoculation, Psa population in MJ-treated plants was increased by 7.4-fold, whereas SA elicitation led to decreased Psa colonization (0.5-fold), as compared with non-elicited inoculated plants. Additionally, elicitation with MJ or SA generally decreased polyphenols and lignin concentrations (by at least 20%) and increased total proteins (by at least 50%). MJ led to the upregulation of SOD, involved in plant antioxidant system, and reporter genes for the jasmonic acid (JA) (JIH and LOX1), abscisic acid (SnRK), SA (ICS1), and ethylene (ACAS1, ETR1 and SAM) pathways. Moreover, it increased ABA (40%) and decreased carotenoids (30%) concentrations. Contrastingly, comparing with non-elicited Psa-inoculated plants, SA application resulted in the downregulation of antioxidant system-related genes (SOD and APX) and of reporter genes for ethylene (ETR1) and JA (JIH and ETR1). This study contributes to the understanding of potential mechanisms involved in kiwifruit plant defences against Psa, highlighting the role of the JA, ABA and ethylene in plant susceptibility to the pathogen.

Survival and prognostic factors in patients with oral squamous cell carcinoma.

BACKGROUND: This study aimed to evaluate sociodemographic and clinical factors influencing overall survival (OS) in patients with oral squamous cell carcinoma (OSCC). MATERIAL AND METHODS: Medical charts of 547 patients with OSCC from a public hospital in northeastern Brazil seen between 1999 and 2013 were evaluated. Survival analysis was performed using the Kaplan-Meier method. The influence of age, sex, ethnicity, clinical stage, anatomical location, type of treatment, and comorbidities on the patients' prognosis was evaluated. Cox proportional hazards regression model was used to identify independent prognostic factors. RESULTS: The 5-year OS was 39%. Multivariate analysis showed that age < 40 years (HR = 2.20; 95%CI: 1.02-4.72) and a single treatment modality (HR = 1.91; 95%CI: 1.37-2.67) were associated with a poor prognosis, while early clinical stage resulted in better outcomes (HR = 0.38; 95%CI: 0.25-0.58). CONCLUSIONS: OSCC patients in advanced clinical stages, diagnosed at a younger age, and submitted to a single therapeutic modality have a poorer prognosis.

Community structures in allelopathic interaction networks: An ecoevolutionary approach.

Evidence is mounting that the race of living organisms for adaptation to the chemicals synthesized by their neighbors may drive community structures. Here, an ecoevolutionary model for community assembly through resource competition, toxin-mediated interactions (allelopathy), and evolutionary branching is investigated. We found that stable communities with increasing biodiversity can emerge at weak allelopathic suppression, but strong chemical warfare drastically impairs diversity. For successive invasion events, the allelopathic interaction networks exhibit, respectively, Gaussian and Weibull degree distributions at weak and strong allelopathy. For the branching process dynamics, degrees scale as power laws truncated by stretched exponentials in both regimes. In addition, allelochemical interactions tend to be arranged in modules with low clustering coefficients and disassortative behavior to ensure community stability. So, in a homogeneous environment, species-rich communities can be assembled only at the context of a weak biochemical warfare between organisms, and even under this regime species interact with only a few others.

The role of seagrass vegetation and local environmental conditions in shaping benthic bacterial and macroinvertebrate communities in a tropical coastal lagoon.

We investigated the influence of seagrass canopies on the benthic biodiversity of bacteria and macroinvertebrates in a Red Sea tropical lagoon. Changes in abundance, number of taxa and assemblage structure were analyzed in response to seagrass densities (low, SLD; high, SHD; seagrasses with algae, SA), and compared with unvegetated sediments. Biological and environmental variables were examined in these four habitats (hereafter called treatments), both in the underlaying sediments and overlaying waters, at three randomly picked locations in March 2017. Differences between treatments were more apparent in the benthic habitat than in the overlaying waters. The presence of vegetation (more than its cover) and changes in sedimentary features (grain size and metals) at local scales influenced the observed biological patterns, particularly for macroinvertebrates. Of note, the highest percentage of exclusive macroinvertebrate taxa (18% of the gamma diversity) was observed in the SHD treatment peaking in the SA for bacteria. Benthic macroinvertebrates and bacteria shared a generally low number of taxa across treatments and locations; approximately, 25% of the gamma diversity was shared among all treatments and locations for macrofauna, dropping to 11% for bacteria. Given the low overlap in the species distribution across the lagoon, sustaining the connectivity among heterogeneous soft sediment habitats appears to be essential for maintaining regional biodiversity. This study addresses a current scientific gap related to the relative contributions of vegetated and unvegetated habitats to biodiversity in tropical regions.

The solar photo-Fenton process at neutral pH applied to microcystin-LR degradation: Fe2+, H2O2 and reaction matrix effects.

Microcystins are a group of cyanotoxins with known hepatotoxic effects, and their presence in drinking water represents a public health concern all over the world. The main objective of this work was to evaluate the solar photo-Fenton process at near-neutral pH in the degradation of microcystin-LR (MC-LR) under conditions close to those found in bloom episodes, with a high concentration of cell debris and natural organic matter (NOM). The influence of experimental parameters such as Fe2+ and H2O2 concentrations, reaction matrix, and the presence of scavenger ions, as well as ecotoxicity before and after treatment, was also evaluated. The reaction matrix was obtained from Microcystis aeruginosa cultivated in ASM-1 medium (ACE1 and ACE2 extracts). H2O2 and Fe2+ concentrations were optimized by 22 factorial design with the central point in a bench-scale solar reactor, using ACE1 extract, and the improved condition was applied in a compound parabolic collector (CPC) reactor, for the ACE2, natural water (RVW) and natural water with M. aeruginosa crude extract (RVCE). Matrix effect assays indicated that radical scavengers present in the medium were responsible for the decrease in the mineralization rates. The solar photo-Fenton process in the CPC reactor achieved COD (75%) and MC-LR (70%) reduction after 120 min at pH = 7.8, [H2O2]/COD = 3.18 and [H2O2]/[Fe2+] = 10 for the ACE2 sample. When the same conditions were applied to the RVCE sample, the process removed 77% of DOC and up to 99% of MC-LR after 45 min of the reaction. Sinapis alba bioassays showed that there was no increase in ecotoxicity after the solar photo-Fenton treatment. These results demonstrate the potential of the solar photo-Fenton process at neutral pH as an additional step in the treatment of natural matrices contaminated with microcystins. In addition, the work reinforces the importance of bioassays in treatment process monitoring.

Role of Recombinant Parvalbumin Gad c 1 in the Diagnosis and Prognosis of Fish Allergy.

BACKGROUND AND OBJECTIVES: The prevalence of fish allergy has increased in recent years. The parvalbumin Gad c 1 is a major cod allergen that is used as a follow-up marker in patients with fish allergy. Objectives: To determine the clinical and laboratory characteristics of a population of patients with fish allergy. To analyze the role of the specific IgE (sIgE) of recombinant Gad c 1 (rGad c 1) and skin prick tests (SPTs) in confirming the acquisition of tolerance to fish. METHODS: We performed a retrospective study of patients with fish allergy from July 1, 2005 to December 31, 2016. The population was characterized according to demographic data, species of fish associated with allergic reactions, and symptoms. The SPT wheal diameter and sIgE for fish and rGad c 1 were evaluated before acquisition of tolerance (T0) and afterwards (T1). RESULTS: The study population comprised 81 patients (68% male). Most reactions were triggered by hake (51%), mackerel (30%), and cod (26%). The most frequent manifestations were urticaria/angioedema (72%), gastrointestinal symptoms (35%), and eczema (33%); 42% of patients experienced anaphylaxis. At T0, the average sIgE values were as follows: cod, 32.2 kUA/L; sardine, 18.4 kUA/L; hake, 17.5 kUA/L; salmon, 13.9 kUA/L; tuna, 4.5 kUA/L; and rGad c 1, 22.9 kUA/L. In patients who acquired tolerance to at least 1 fish species (n=60; 74%), the mean value of rGad c 1 at T1 (5.1 kUA/L) was significantly lower than at T0 (16.8 kUA/L) (P=.001). Significant values were also recorded for the average diameter of the SPT wheal and the evaluations at T0 and T1 for hake (9.42 mm/3.79 mm) and salmon (7.8 mm/2.8 mm) (P=.002 and P=.026, respectively). CONCLUSION: The decrease in sIgE to rGad c 1 and the mean wheal diameter of SPT for hake and salmon can be used as markers of prognosis in the acquisition of tolerance by fish-allergic patients.

Neurohormonal modulation: The new paradigm of pharmacological treatment of heart failure.

The current paradigm of medical therapy for heart failure with reduced ejection fraction (HFrEF) is triple neurohormonal blockade with an angiotensin-converting enzyme inhibitor (ACEI), a beta-blocker (BB) and a mineralocorticoid receptor antagonist (MRA). However, three-year mortality remains over 30%. Stimulation of counter-regulatory systems in addition to neurohormonal blockade constitutes a new paradigm, termed neurohormonal modulation. Sacubitril/valsartan is the first element of this new strategy. PARADIGM-HF was the largest randomized clinical trial conducted in HFrEF. It included 8442 patients and compared the efficacy and safety of sacubitril/valsartan versus enalapril. The primary endpoint was the composite of cardiovascular mortality and hospitalization due to HF, which occurred in 914 (21.8%) patients receiving sacubitril/valsartan and in 1117 (26.5%) patients receiving enalapril (HR 0.8, 95% CI 0.73-0.87, p=0.0000002; NNT 21). Sacubitril/valsartan reduced both primary endpoint components, as well as sudden cardiac death, death due to worsening HF, and death from all causes. Patients on sacubitril/valsartan reported less frequent deterioration of HF and of quality of life, and discontinued study medication less frequently because of an adverse event. PARADIGM-HF demonstrated the superiority of sacubitril/valsartan over enalapril, with a 20% greater impact on cardiovascular mortality compared to ACEIs. Accordingly, in 2016, the European (ESC) and American (ACC/AHA/HFSA) cardiology societies simultaneously issued a class I recommendation for the replacement of ACEIs by sacubitril/valsartan in patients resembling PARADIGM-HF trial participants.

Energy and protein requirements for maintenance of Texel lambs.

It can be hypothesized that the body composition characteristics of different sheep breeds affect their nutritional requirements. However, no study has yet been carried out to determine the nutritional requirements for maintenance of Texel purebred lambs, despite their growing importance in sheep meat production globally. Our objective was therefore to determine the energy and protein requirements for maintenance of Texel lambs. Thirty-four Texel lambs were used, all intact males that were weaned at 50 days old, and confined in individual pens. Two experiments were conducted, as follows. In Experiment 1, a digestibility assay was performed to determine the dietary energy value, in a 3×3 double Latin square design, in which lambs were submitted to three levels of feed restriction (0%, 55% and 70% of ad libitum feed intake). In Experiment 2, the energy and protein requirements for maintenance of Texel lambs from 21 to 40 kg BW were determined using a randomized block design, in which lambs were also submitted to three levels of feed restriction (0%, 55% and 70% of ad libitum feed intake). The requirements for net energy for maintenance (NEm), metabolizable energy for maintenance (MEm), net protein for maintenance (NPm) and metabolizable protein for maintenance (MPm) were determined. The digestibility of dry matter, energy, protein and metabolizability were similar between food restriction levels, averaging 74.4%, 75.5%, 80.3% and 0.636, respectively. The NEm determined for growing Texel lambs was 263 kJ/kg of the metabolic fasting BW (FBW), the MEm was 417 kJ/kg0.75 FBW and the efficiency of use of MEm was 0.63. In addition, the NPm was 1.24 g/day per kg0.75 FBW and the MPm was 2.98 g/day per kg0.75 FBW. The energy requirements of Texel lambs are different from those reported in the literature, possibly due to differences between breeds, diets and environmental effects, whereas the protein requirements are different from literature mainly due to methodological differences; further studies are need to address these aspects that affects the nutritional requirements for raising sheep from different breeds in different environments.

Gold nanoparticle-carboxymethyl cellulose nanocolloids for detection of human immunodeficiency virus type-1 (HIV-1) using laser light scattering immunoassay.

It is estimated that over 100 million people have been infected with human immunodeficiency virus (HIV-1) resulting in approximately 30 million deaths globally. Herein, we designed and developed novel nano-immunoconjugates using gold nanoparticles (AuNPs) and carboxymethylcellulose (CMC) biopolymer, which performed simultaneously as an eco-friendly in situ reducing agent and surface stabilizing ligand for the aqueous colloidal process. These AuNPs-CMC nanocolloids were biofunctionalized with the gp41 glycoprotein receptor (AuNPs-CMC-gp41) or HIV monoclonal antibodies (AuNPs-CMC_PolyArg-abHIV) for detection using the laser light scattering immunoassay (LIA). These AuNPs-CMC bioengineered nanoconjugates were extensively characterized by morphological and physicochemical methods, which demonstrated the formation of spherical nanocrystalline colloidal AuNPs with the average size from 12 to 20 nm and surface plasmon resonance peak at 520 nm. Thus, stable nanocolloids were formed with core-shell nanostructures composed of AuNPs and biomacromolecules of CMC-gp41, which were cytocompatible based on in vitro cell viability results. The AuNPs-CMC-gp41 nanoconjugates were tested against HIV monoclonal antibodies conjugates (AuNPs-CMC_PolyArg-abHIV) using the light scattering immunoassay (LIA) where they behaved as active nanoprobes for the detection at nM level of HIV-1 antigenic proteins. This strategy offers a novel nanoplatform for creating bioprobes using green nanotechnology for the detection of HIV-1 and other virus-related diseases.

Adsorption of methylene blue on agroindustrial wastes: Experimental investigation and phenomenological modelling.

In this work, agro-wastes coming from soursop (peel, seeds and pulp fiber) and sugarcane (bagasse) are used as low-cost biosorbents to remove methylene blue (MB) from aqueous media. Batch experiments are performed under different experimental conditions investigating the effects of biosorbent amount, dye concentration and stirring rate. The best results were found using soursop wastes for a MB concentration of 100 mg L-1, using 0.75 g of residue and a stirring rate of 110 rpm, removing a percentage above 90%. Theoretically, adsorption kinetic can be successfully described by the pseudo-second order model. Redlich-Peterson and Sips models are adopted to interpret the equilibrium adsorption of MB on sugarcane bagasse and soursop residue, respectively. Interestingly, the monolayer model with single energy derived by statistical physics theory is also applied for a deeper explanation of the adsorption mechanism of MB on both the adsorbents. The application of this model allows defining the adsorption geometry of the investigated adsorbate and provides important information about the interactions between the adsorbate and sorbents. In particular, the modelling analysis by statistical physics allows defining that the dye molecules are adsorbed in vertical position and the adsorption process is multi-molecular (i.e. n > 1). Finally, the estimation of adsorption energy suggested that MB adsorption on biosorbent is a physisorption process.

Coral reef degradation affects the potential for reef recovery after disturbance.

The loss of coral cover is often accompanied by an increase of benthic algae, a decline in biodiversity and habitat complexity. However, it remains unclear how surrounding communities influence the trajectories of re-colonization between pulse disturbance events. Over a 12-month field experiment in the central Red Sea, we examined how healthy (hard-coral dominated) and degraded (algae-dominated) reef areas influence recruitment and succession patterns of benthic reef foundation communities on bare substrates. Crustose coralline algae and other calcifiers were important colonizers in the healthy reef area, promoting the accumulation of inorganic carbon. Contrary, substrates in the degraded area were predominantly colonized by turf algae, lowering the accumulation of inorganic carbon by 178%. While coral larvae settlement similarly occurred in both habitats, degraded areas showed 50% fewer recruits. Our findings suggest that in degraded reefs the replenishment of adult coral populations is reduced due to recruitment inhibition through limited habitat complexity and grazing pressure, thereby restraining reef recovery.

Socio-epidemiological characterisation of blood donors with asymptomatic Leishmania infantum infection from three Brazilian endemic regions and analysis of the transfusional transmission risk of visceral leishmaniasis.

OBJECTIVES: This study assessed the prevalence of visceral leishmaniasis in blood donors from three endemic regions in Brazil and evaluated the risk of transmission by transfusion. BACKGROUND: Despite strong evidence of the transmission of visceral leishmaniasis through blood transfusion, the real risk, an essential condition for taking effective measures to control this serious disease, has not been determined. METHODS: A multicentre study was performed in highly endemic areas. Candidates eligible for their first blood donation underwent a socio-epidemiological interview, and blood samples were collected for enzyme-linked immunosorbent assay (ELISA) analysis, Western blot and polymerase chain reaction (PCR). Patients transfused with red blood cells or random platelet concentrates collected from these donors were also studied. The results were analysed using descriptive statistics and prevalence estimates, with significance defined as p-values <0·05. RESULTS: Of the 608 eligible donors, 37 (6·1%) were positive for visceral leishmaniasis as per ELISA. The socio-epidemiological analysis showed a significantly higher prevalence in non-Caucasians (p = 0·008). Among 296 patients who received blood components from these donors, the pre-transfusion seropositivity was 7·7%, and 13 patients received blood positive for Leishmania infantum. Six patients were followed up for 90 days, of which two (33·3%) had serological conversion at 60 days. CONCLUSIONS: The results confirm the high prevalence of L. infantum seropositivity among donors in the three regions; the seroconversion in a short period of time in two of six patients suggests the possibility of transmission of the infection by transfusion.