Memorias Do Instituto Oswaldo Cruz[JOURNAL]
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200 papers
Miracidia as main source for autofluorescence of Schistosoma mansoni eggs.
Pereira DSCA, Oliveira LOVO, Firmino FT … +6 more , Hanscheid T, Pulak R, Jones M, Dolabella S, Negrão-Corrêa D, Graeff-Teixeira C
Mem Inst Oswaldo Cruz · 2026 Mar · PMID 41810683 · Full text
BACKGROUND: Egg detection still has a role in schistosomiasis control, as a screening strategy or to provide a reference standard for the assessment of the accuracy of other diagnostic tools. The Helmintex method is high...
BACKGROUND: Egg detection still has a role in schistosomiasis control, as a screening strategy or to provide a reference standard for the assessment of the accuracy of other diagnostic tools. The Helmintex method is highly sensitive but laborious, and several improvements of it, including automated egg detection, are currently under development. OBJECTIVE: We conducted a preliminary evaluation of Schistosoma mansoni eggs' autofluorescence as a distinctive marker amid very complex fecal sediments. METHODS: Eggs from mouse livers and human feces were examined under a fluorescence microscope. FINDINGS: More intense green fluorescence (greater for miracidia than for eggshell) was consistently detected using a B-2A filter (FITC, 420-495 nm). MAIN CONCLUSIONS: These findings may help to improve diagnostic methods, especially with automated egg detection systems. Besides access to safe water and adequate sanitation, as well as health education and the treatment of infected individuals, laboratory diagnosis is a key measure that can help eliminate schistosomiasis as a public health problem.
Molecular characterisation of Trypanosoma cruzi in Triatoma dimidiata from a highland locality in western Panamá.
Pineda VJ, González K, Calzada JE … +1 more , Saldaña A
Mem Inst Oswaldo Cruz · 2026 Mar · PMID 41810681 · Full text
BACKGROUND: Triatoma dimidiata is a widely distributed vector of Trypanosoma cruzi in Mesoamerica, but its epidemiological role in most regions of Panamá remains poorly understood. OBJECTIVES: To investigate the presence...
BACKGROUND: Triatoma dimidiata is a widely distributed vector of Trypanosoma cruzi in Mesoamerica, but its epidemiological role in most regions of Panamá remains poorly understood. OBJECTIVES: To investigate the presence, infection status, and feeding behaviour of T. dimidiata populations in peridomestic areas of Palmira Arriba, western Panamá. METHODS: Entomological surveys were conducted in five peridomestic sites of a rural highland community. Thirty-seven triatomines (13 adults and 24 nymphs) were collected from wooden piles and construction materials in contact with the ground. DNA from 30 specimens was analysed by polymerase chain reaction (PCR) for T. cruzi detection, genotyping [discrete typing unit (DTU) and haplotype identification], and blood meal source determination through cytochrome b amplification. FINDINGS: Twenty-one insects (70.0%) were positive for T. cruzi. Sixteen infections (76.2%) belonged to DTU I (TcI), including 13 TcIDOM and 14 TcIa genotypes, both linked to domestic and sylvatic cycles. Blood meal analysis revealed one mammalian and two avian feedings, indicating opportunistic behaviour. MAIN CONCLUSIONS: This study provides the first molecular confirmation of T. cruzi infection in T. dimidiata from Palmira Arriba. The combination of high infection prevalence, multiple developmental stages, and recent feeding suggests active local transmission favoured by humid and cool ecological conditions. Expanded surveillance and integrative One Health approaches are needed to elucidate transmission dynamics in highland rural Panamá.
Entomo-virological investigation during the epizootic outbreak of sylvatic yellow fever in Rio Grande do Sul, Brazil, between 2021 and 2022.
Müller NFD, Lima MM, Dos Santos E … +12 more , Campos AAS, Menegazzi TR, Melgarejo AS, Paredes-Galarza B, Violet-Lozano L, Oliveira MT, Oliveira CH, Roehe PM, Campos FS, de Abreu FVS, Cardoso JDC, Franco AC
Mem Inst Oswaldo Cruz · 2026 Mar · PMID 41810680 · Full text
BACKGROUND: Yellow fever virus (YFV) re-emerged among non-human primates (NHPs) in Rio Grande do Sul in early 2021, more than a decade after its last detection in the state. The spread of the virus was accompanied by inc...
BACKGROUND: Yellow fever virus (YFV) re-emerged among non-human primates (NHPs) in Rio Grande do Sul in early 2021, more than a decade after its last detection in the state. The spread of the virus was accompanied by increased mortality among NHPs. OBJECTIVES: To conduct entomological surveillance and molecular detection of YFV and other Orthoflavivirus species in mosquito samples collected from affected and potentially receptive areas. METHODS: Mosquitoes were collected during epizootics using human landing catches, BG-Pro traps, and ovitraps. Virus detection was performed using reverse transcription real-time polymerase chain reaction (RT-qPCR) assays targeting YFV and pan-Orthoflavivirus sequences. FINDINGS: A total of 1,210 mosquitoes, representing 26 taxa, were collected across 17 municipalities. Psorophora ferox was the most abundant species, followed by Culex (Culex) spp., accounting for 27% and 12% of the specimens, respectively. Haemagogus leucocelaenus, the primary YFV vector in the region, was also among the most frequently captured species, representing 7%. In total, 203 mosquito pools were assembled by species, location, and date of collection. RT-qPCR analysis did not detect YFV or other Orthoflavivirus RNA in any of the samples. MAIN CONCLUSIONS: Although mosquitoes were collected during a period of active YFV circulation, the absence of virus detection suggests that arboviral circulation in vector populations may occur at low frequencies, even during outbreaks.
Comprehensive identification and co-expression analysis of long non-coding RNAs across eight timepoints of Schistosoma mansoni life cycle.
Arêdes-Rocha F, Chaparro C, Grunau C … +1 more , Guerra-Sá R
Mem Inst Oswaldo Cruz · 2026 · PMID 41810679 · Full text
BACKGROUND: Long non-coding RNAs (lncRNAs) are important regulatory molecules that can be considered potential biomarkers for schistosomiasis. However, the identification and characterisation of these molecules in such c...
BACKGROUND: Long non-coding RNAs (lncRNAs) are important regulatory molecules that can be considered potential biomarkers for schistosomiasis. However, the identification and characterisation of these molecules in such complex organism as Schistosoma mansoni, remains very challenging. OBJECTIVES: This study aimed to identify novel lncRNAs in S. mansoni using RNA-seq libraries representative of six developmental stages (eggs, miracidia, sporocysts, cercariae, schistosomula, and juveniles). METHODS: A pipeline for lncRNAs identification was defined and applied to 41 RNA-seq libraries of eggs, miracidia, 1-day, 5-days, 32-days sporocysts, cercariae, schistosomula, and juveniles of S. mansoni. Novel identified lncRNAs and annotated mRNAs were submitted to a weighted co-expression network analysis (WGCNA) to establish lncRNA-mRNAs correlation. FINDINGS: We identified 1,082 novel lncRNAs, mostly presenting stage-specific expression. Co-expression analysis demonstrate that MSTRG.5305.1 can potentially target MEGs and tetraspanin, essential for juvenile worm survival, making it a promising candidate for further functional studies. MAIN CONCLUSIONS: These findings expand the current catalog of S. mansoni lncRNAs and provide new insights into their potential roles in parasite development and host adaptation. Further functional validation could reveal new molecular targets for schistosomiasis control.
Transcriptomics of Plasmodium vivax rosetting.
Bourgard C, Ferraboli JW, Lopes SCP … +4 more , Lacerda MVG, Sunnerhagen P, Albrecht L, Costa FTM
Mem Inst Oswaldo Cruz · 2026 Mar · PMID 41810678 · Full text
BACKGROUND: Plasmodium vivax rosetting is a cytoadhesion phenomenon associated with parasite virulence and clinical manifestations of malaria. However, the molecular mechanisms underlying this process remain poorly under...
BACKGROUND: Plasmodium vivax rosetting is a cytoadhesion phenomenon associated with parasite virulence and clinical manifestations of malaria. However, the molecular mechanisms underlying this process remain poorly understood. Comparative transcriptomic analysis between isolates with different rosetting capacities may provide insights into the molecular base and clinical outcome of parasite populations with distinct rosetting characteristics. OBJECTIVES: Our study aims to identify and describe the transcription profile of P. vivax isolates with high and low rosetting rates. METHODS: We used RNA-seq to compare the transcriptomes of 10 field P. vivax isolates from the Brazilian Amazon. FINDINGS: Among the 492 differentially expressed genes of P. vivax isolates with high rosetting (HR) versus low rosetting (LR) formation, 172 (34,96%) are annotated as genes conserved within Plasmodium and of unknown function. The expression profiles of the other 320 genes (65,04%) highlight the importance of integral membrane proteins and membrane-associated proteins with adhesive or adhesin-like properties, representing 10% of the transcribed genes (53 genes), such as Plasmodium Helical Interspersed Sub-telomeric (PHIST) proteins in rosetting phenotypes. Transcriptomic analyses revealed that approximately 4% (19 genes) of differentially expressed genes were kinases and 50% (248 genes) other proteins. Among cell surface proteins and integral/membrane-associated proteins, differentiated expression and positive regulation of representative 6-cysteine gene family were observed in HR formation group, which includes a tryptophan-rich protein (TRAG16), the 41K blood stage antigen precursor 41-3 protein, and merozoite surface protein 7-like (MSP7-like). MAIN CONCLUSIONS: These results contribute to understanding the molecular basis of P. vivax rosetting.
Evaluation of the insecticide custody chain and its relationship with malaria burden in the Brazilian Amazon: a process and exploratory impact assessment (2019-2023).
Dourado ML, Silva RAE, Castro MC … +4 more , Peterka CRL, Kluge CR, Castro D, Lima JBP
Mem Inst Oswaldo Cruz · 2026 · PMID 41810677 · Full text
BACKGROUND: Malaria remains a major public health concern in Brazil, with the Amazon region accounting for 99.9% of the country's cases. Indoor residual spraying (IRS) using Etofenprox 20% PM is a core vector control str...
BACKGROUND: Malaria remains a major public health concern in Brazil, with the Amazon region accounting for 99.9% of the country's cases. Indoor residual spraying (IRS) using Etofenprox 20% PM is a core vector control strategy. However, inefficiencies in the insecticide custody chain, including planning, storage, and distribution, may compromise intervention effectiveness. OBJECTIVES: This study aimed to evaluate the insecticide custody chain from a process perspective, identifying logistical bottlenecks, while also exploring potential impact by examining associations between insecticide allocation and malaria burden in Brazil and in three high-incidence municipalities in the state of Amazonas (Barcelos, Tefé, and São Gabriel da Cachoeira) from 2019 to 2023. The underlying hypothesis is that in a well-functioning system, insecticide distribution should be correlated with malaria risk determinants, such as epidemiological and environmental variables, rather than merely responding to reported case counts. METHODS: A mixed-methods approach was used. Quantitative analysis applied Pearson correlation, simple and multiple linear regressions (with time-lag), and ARIMA models to evaluate associations between insecticide volume and malaria cases, incorporating environmental and demographic covariates. A complementary qualitative assessment, based on a structured risk matrix, examined failures across four stages of the custody chain: planning, storage, application, and monitoring. FINDINGS: At the national level, insecticide volume was significantly associated with malaria cases (β = 0.161; p = 0.038; R² = 0.74) and deforestation (β = 0.626; p = 0.034). Time-series analysis revealed a reactive pattern, with insecticide allocation often lagging behind malaria incidence peaks. In the municipalities studied, models lacked statistical significance, but trends suggested weak local planning and disconnects from risk-based forecasting. The risk matrix revealed systemic weaknesses, including limited data interoperability, insufficient integration of environmental indicators, and poor federal coordination. MAIN CONCLUSIONS: The current custody chain functions reactively and lacks integration with surveillance and predictive environmental data, contradicting World Health Organization (WHO) recommendations. Structural reforms are urgently needed. These include: (i) risk-based planning incorporating environmental variables, (ii) interoperable information systems, (iii) improved surveillance of vector resistance, and (iv) intergovernmental agreements for equitable and efficient resource allocation. Findings highlight the need for strategic reorientation of IRS logistics toward anticipatory and data-driven planning. Strengthening the custody chain through intersectoral coordination and environmental intelligence is essential not only to improve operational efficiency but also to increase the cost-effectiveness and epidemiological impact of malaria control interventions in the Amazon. Lessons learned may inform broader efforts in other endemic regions aiming for malaria elimination.
Transcriptomic dynamics reveals sequential acquisition of complement resistance during prolonged starvation of Trypanosoma cruzi epimastigote.
Pérez-Díaz L, Smircich P, Hernandez F … +3 more , Ciganda M, Duhagon MA, Garat B
Mem Inst Oswaldo Cruz · 2026 Mar · PMID 41810676 · Full text
BACKGROUND: The life cycle of the parasitic protozoan Trypanosoma cruzi, the etiological agent of Chagas disease (CD), includes two well-recognised insect-dwelling stages: the replicative non-infective epimastigotes and...
BACKGROUND: The life cycle of the parasitic protozoan Trypanosoma cruzi, the etiological agent of Chagas disease (CD), includes two well-recognised insect-dwelling stages: the replicative non-infective epimastigotes and the non-replicative infective metacyclic trypomastigotes. Nonetheless, the existence of multiple intermediate forms has been reported. Since nutrient restriction is considered one of the main factors driving metacyclogenesis and is very frequent due to the long-term starvation periods that the insect vectors commonly undergo, we have studied the transcriptomic effects of nutrient restriction on long-lasting epimastigote cultures. We previously reported that in these conditions, we observed a long stationary phase characterised by an RNA content per cell three times smaller than the epimastigote's and a distinctive transcriptomic profile. Remarkably, our study identified gene expression changes that distincty characterise transitional parasite forms enriched by nutrient restriction. OBJECTIVES: In this work we focused on pathogenic genes to further characterise the transcriptomic dynamics accompanying the nutrient restriction within the insect-dwelling parasite stage. METHODS: The alterations of morphology, growth rate and complement resistance of parasite population on long-lasting epimastigote cultures as well as the transcriptomic dynamics was studied. FINDINGS: We found a gene expression early rise of surface proteins (such as trans-sialidase and GP63) and even a rise of TcTASV and δ-amastin, which is not accompanied by increased expression of metacyclic transcript markers. In addition, we found increased expression of genes coding for proteins involved in two other processes activated during the differentiation of epimastigotes to the infective form of the parasite: autophagy (Atg4, Atg7, Atg8.2) and complement resistance (TcCRP and T-DAF). MAIN CONCLUSIONS: Altogether, these results, plus our previous identification of transcriptomic markers for transitional parasites, further support earlier proposals of a specific parasite stage that morphologically resembles epimastigotes but exhibits distinctive biological characteristics, including key features related to infectivity.
LC3-associated phagocytosis in macrophage responses to Paracoccidioides spp.
de Oliveira Júnior GP, de Sousa HR, Gorgonha KCM … +14 more , Tomaz LLM, Borges TKDS, Rangel KT, Fabricant S, Koser Gustafson F, Albuquerque LF, Rossi Neto A, Hurtado FA, Paes HC, Casadevall A, Silva-Pereira I, Felipe MSS, Albuquerque P, Nicola AM
Mem Inst Oswaldo Cruz · 2026 Mar · PMID 41810675 · Full text
BACKGROUND: Paracoccidioidomycosis (PCM) is a systemic infection that is endemic to Latin America, caused by thermodimorphic fungi from the Paracoccidioides genus. These fungi are facultative intracellular parasites of m...
BACKGROUND: Paracoccidioidomycosis (PCM) is a systemic infection that is endemic to Latin America, caused by thermodimorphic fungi from the Paracoccidioides genus. These fungi are facultative intracellular parasites of macrophages. LC3-associated phagocytosis (LAP), a non-canonical form of autophagy, plays a critical role in the response of these phagocytes to similar pathogens. OBJECTIVES: In this study, we investigated the role of LAP in the macrophage responses to Paracoccidioides spp. METHODS: We detected LAP in macrophages infected with Paracoccidioides spp by immunofluorescence microscopy with antibodies to LC3. Piceatannol and diphenyleneiodonium chloride (DPI), respectively Syk and nicotinamide adenine dinucleotide phosphate oxidase (NADPH) inhibitors, were used to understand the role their pathways played. To determine the function of LAP, we targeted ATG5, a key autophagy gene, by RNA interference. FINDINGS: We observed LC3 recruitment to phagosomes containing Paracoccidioides spp. in RAW264.7 and J774.16 cell lines and in bone marrow-derived macrophages. ATG5 RNA interference reduced the antifungal activity of J774.16 cells, highlighting the importance of LC3 recruitment for effective fungal control. Interestingly, pharmacological inhibition of Syk kinase and NADPH oxidase pathways, essential for LAP against Aspergillus fumigatus and Candida albicans, did not impair LAP against P. brasiliensis. MAIN CONCLUSIONS: This suggests distinct triggering mechanisms, possibly due to differences in the fungal cell surface composition. These findings suggest that LAP plays a significant role in the host defense against Paracoccidioides spp. and may represent a promising target for host-directed PCM therapies.
Schistosoma mansoni soluble egg antigen and its key proteins differentially affect dextran sodium sulphate-induced inflammatory bowel disease.
Fan HW, Lam HYP
Mem Inst Oswaldo Cruz · 2026 Mar · PMID 41779555 · Full text
BACKGROUND: Inflammatory bowel disease (IBD) is an increasingly prevalent disease, affecting over seven million people worldwide and imposes a heavy burden on public health. The rising prevalence of IBD may be attributed...
BACKGROUND: Inflammatory bowel disease (IBD) is an increasingly prevalent disease, affecting over seven million people worldwide and imposes a heavy burden on public health. The rising prevalence of IBD may be attributed to the hygiene hypothesis, which suggests that reduced exposure to parasites and microbes may weaken the immune system, thereby increasing susceptibility to developing IBD. Studies suggest helminths and their secretory products can modulate the host immunity and attenuate IBD. Our previous research also demonstrated that intestinal schistosomiasis can mitigate chronic IBD symptoms by restoring intestinal immune balance and dysbiosis. OBJECTIVES: While the primary pathology of schistosomiasis results from egg entrapment, we hypothesised that soluble egg antigen (SEA), known for its strong immunomodulatory effect, may contribute to the improvement of IBD. Given that SEA comprises multiple different proteins, identifying the role of individual components may clarify the therapeutic potential of SEA in IBD. METHODS: BALB/c mice were induced with dextran sodium sulphate (DSS) to develop IBD. Throughout the experiment, mice were intraperitoneally injected with 250 μg/mL crude SEA extract or recombinant egg antigen proteins, including SM14, GST28, and SMP40, three times a week. Colonic histopathology was assessed by H&E staining, and the immune response was evaluated through periodic acid-Schiff (PAS) staining, immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), western blot, and quantitative polymerase chain reaction (qPCR). FINDINGS: Both SEA and Smp40 alleviated DSS-induced IBD, whereas SM14 exacerbated the disease and led to colonic dysplasia. In contrast, GST28 showed no significant effect on IBD. Further investigation revealed that all tested proteins modulated the immune response in mice, though each did so in different ways. These differences in immune modulation may underlie the varying disease outcomes observed. MAIN CONCLUSIONS: While SEA has shown therapeutic promise in IBD, it is also important to investigate the safety and mechanisms of individual antigens before considering their clinical application in the future.
Mitochondrial genomes and phylogeny of Atratus and Educator Group species of the Melanoconion Section of Culex (Melanoconion) (Diptera: Culicidae).
Oliveira TMP, Foster PG, Sá ILR … +1 more , Sallum MAM
Mem Inst Oswaldo Cruz · 2026 Mar · PMID 41779554 · Full text
BACKGROUND: Culex (Melanoconion) species are known to act as vectors for different arboviruses, and little is known about the mitochondrial genome of these species. OBJECTIVES: Aiming to expand the genetic knowledge of t...
BACKGROUND: Culex (Melanoconion) species are known to act as vectors for different arboviruses, and little is known about the mitochondrial genome of these species. OBJECTIVES: Aiming to expand the genetic knowledge of this subgenus, a 12Kb fragment of the mitochondrial genome was sequenced from 23 specimens belonging to the Atratus and Educator Groups of the subgenus Melanoconion of Culex. METHODS: The sequenced specimens were morphologically identified as Culex dunni, Culex ensiformis, Culex theobaldi, Culex trigeminatus, Culex eknomios, Culex zeteki, Culex near commevynenis, Culex angularis, Culex longistriatus, and Culex near vaxus. The reads were assembled with the reference genome of Culex quinquefasciatus and MITOS2 was used for gene annotation. Values of guanine-cytosine (GC) and adenine-thymine (AT) skews, nucleotide diversity, ratio between non-synonymous (Ka) and synonymous (Ks) substitution, and nucleotide composition were calculated, and phylogenetic analysis was performed. FINDINGS: As in other Culex mitogenomes, the partial mitochondrial genomes include 12 protein coding genes (PCGs), 15 tRNA, and 1 rRNA (rrnL). The PCGs showed no length variation between the species studied. ND5 gene presented one less base in the new sequences, which generated a stop codon and, consequently, a shorter length in relation to the Cx. quinquefasciatus sequence reference. All specimens showed a positive value for AT-skew and negative for GC-skew. Nucleotide diversity varied between 0.00407 and 0.12085. Ka/Ks values ranged from 0.0 to 2.775. MAIN CONCLUSIONS: Leucine and Serine were the most abundant amino acids. Phylogenetic analysis suggested three putative species.
Extracellular vesicles isolated from the plasma of COVID-19 and sepsis patients: characterisation and association with clinical outcomes.
de Carvalho JFN, Meneghetti P, Barbosa GR … +8 more , Silvestrini MMA, Santos SS, Freitas FG, Boschetti D, Bellei NCJ, Teixeira-Carvalho A, Torrecilhas AC, Salomao R
Mem Inst Oswaldo Cruz · 2026 Mar · PMID 41779553 · Full text
BACKGROUND: Extracellular vesicles (EVs) are involved in the pathogenesis of severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection. OBJECTIVES: We analysed the concentration, size, cellular origin, and c...
BACKGROUND: Extracellular vesicles (EVs) are involved in the pathogenesis of severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection. OBJECTIVES: We analysed the concentration, size, cellular origin, and capacity for carrying viral components in plasma samples from patients with Coronavirus disease 2019 (COVID-19) and sepsis. METHODS: Plasma samples from COVID-19 patients admitted to the intensive care unit (ICU) with sepsis (N = 42) and healthy individuals (N = 19) were analysed. EVs were characterised by size and concentration using nanoparticle tracking analysis (NTA), polymerase chain reaction (RT-qPCR) for SARS-CoV-2 components, and flow cytometry for immunophenotyping. EVs were marked with phosphatidylserine and tetraspanins. Cellular origin markers were used for neutrophils, endothelial cells, T lymphocytes and platelets. Cryo-EM was used to assess EV size and integrity. FINDINGS: NTA showed an increased concentration of microparticles in patients. RT-qPCR analysis of EVs detected the virus in 14 samples, two of which were consistent with the Gamma variant. EVs predominantly derived from T cells and platelets and demonstrated an increased expression of CD81 in individuals who died. Cryo-EM revealed EVs with an average size of 200 nm. MAIN CONCLUSIONS: Our findings suggest that patients' EVs likely harboured viral components, suggesting their potential role as carriers of SARS-CoV-2. In addition, EVs from deceased patients demonstrated elevated levels of CD81 expression.
Detection of Trypanosoma cruzi-infected triatomines in Iquitos: possible incipient colonisation in the largest metropolis of the Peruvian Amazon.
Díaz-Soria F, Zevallos K, Cabrera-Campos B … +9 more , Sinti-Hesse C, Jaume-Ramis S, Alava-Flores W, Acho-Bernuy D, Vega-Chirinos S, Pinto-Caballero J, Ramal-Asayag C, Sihuincha M, Paredes-Esquivel C
Mem Inst Oswaldo Cruz · 2026 Feb · PMID 41779552 · Full text
BACKGROUND: While Chagas disease (CD) has been controlled in many South American regions, the Amazon basin has emerged as a new focus of transmission. Metropolitan Iquitos (Loreto, Peru), has recently shown signs of pote...
BACKGROUND: While Chagas disease (CD) has been controlled in many South American regions, the Amazon basin has emerged as a new focus of transmission. Metropolitan Iquitos (Loreto, Peru), has recently shown signs of potential disease emergence. OBJECTIVE: To assess the risk of CD transmission by evaluating triatomine presence and infection rates in households across Iquitos and nearby communities. METHODS: Entomological surveillance was conducted in domestic and peridomestic environments, following blood donor screenings (2011-2018) that confirmed local Trypanosoma cruzi cases. Triatomines were collected manually, with traps, and through community reporting. Specimens were identified, epidemiological indices calculated, and infestation risk factors analysed using penalised logistic regression, receiver operating characteristic (ROC)/area under the curve (AUC) metrics, and exploratory principal component analysis (PCA). FINDINGS: Of 142 houses visited, 113 were inspected, yielding a density index of 0.26. Nine houses were infested, mostly in Loboyacu, with 29 adult triatomines collected - by Rhodnius robustus (89.7%) and Panstrongylus geniculatus. T. cruzi infection was confirmed, and palm roofs emerged as the strongest predictor of infestation [odds ratio (OR) > 16, p < 0.001]. MAIN CONCLUSIONS: This first evidence of T. cruzi circulation in sylvatic triatomines within Metropolitan Iquitos highlights an emerging risk of CD. Although vectors remain scarce, palm-roofed houses, deforestation, and urban expansion may facilitate future transmission.
Holocene man-occupied caves and transformed wetlands as facilitating factors for Leishmania infantum in South America.
Ribeiro SP, Dias CP, Duarte RV … +9 more , de Almeida MFB, Malta LGF, Andrade Filho JD, Reis AB, Pereira MH, Grelle CE, Valenzuela JG, Serafim TD, Gontijo NF
Mem Inst Oswaldo Cruz · 2026 · PMID 41711768 · Full text
BACKGROUND: In the Holocene, South American humans transformed large extensions of the continent, especially in cave ecosystems. Such transformations produced predictable eutrophic habitats that could have attracted foxe...
BACKGROUND: In the Holocene, South American humans transformed large extensions of the continent, especially in cave ecosystems. Such transformations produced predictable eutrophic habitats that could have attracted foxes and further favored the adaptation of Lutzomyia longipalpis, insect vector of American Visceral Leishmaniosis (AVL), to human-contaminated habitats. OBJECTIVES: Here we present spatial analyses on the distribution of caves, Holocene human populations, the present-days main wild reservoirs of Leishmania infantum, Cerdocyon thous and Lycalopex vetulus, and the vector Lu. longipalpis in Brazil. METHODS: The presence or absence of Lu. longipalpis in function of cave abundance, based on coordinates of all recorded samples (Fiocruz and GBIF database and literature), and cave locations taken from ICMBio/CECAV database, were tested by contingency table. The overlap in the distribution of Lu. longipalpis, C. thous and L. vetulus with humans from Holocene was tested by permutational multivariate analysis of variance (PERMANOVA) from a nonmetric multidimensional scaling (NMDS), using published archaeological data on human demography and ICMBio's data on caves and foxes. FINDINGS: Caves are present in 18% of Brazilian municipalities, and Lu. longipalpis were significantly more frequent in these places than in municipalities without caves. Native humans and foxes have broader distributions than caves but co-occurred with Lu. longipalpis in cave-ecosystems. MAIN CONCLUSION: The most relevant implication of our findings is that visceral leishmaniasis should be considered a long-term human related disease, associated with few sandfly species well adapted to our modified, and heavily contaminated, environments.
Behavioural responses of Anopheles darlingi (Diptera: Culicidae) to host odours: insights from vertical and horizontal olfactometers.
Santos TCD, Rodrigues MMS, Batista EPA … +4 more , Paixão KDS, Eiras ÁE, Laporta GZ, Silva AAE
Mem Inst Oswaldo Cruz · 2026 · PMID 41711767 · Full text
BACKGROUND: Anopheles darlingi is the primary vector of malaria in the Americas, particularly in the Amazon, where it thrives in forest margins. This species exhibits considerable flexibility in feeding behaviour, adapti...
BACKGROUND: Anopheles darlingi is the primary vector of malaria in the Americas, particularly in the Amazon, where it thrives in forest margins. This species exhibits considerable flexibility in feeding behaviour, adapting to environmental conditions and host availability. Previous studies on its attraction to human odour have relied mainly on baited traps, with limited research using vertical olfactometry to explore host-seeking behaviour. OBJECTIVES: This study aimed to assess the feasibility of using vertical and horizontal olfactometry to investigate the behavioural responses of both wild and laboratory-reared (F1) An. darlingi females to human odours. The odours were presented through direct (hands and feet) and indirect (sweat-impregnated synthetic substrates) stimuli. METHODS: Wild mosquitoes were collected from Porto Velho and Candeias do Jamari, Brazil, and laboratory-reared (F1) mosquitoes were bred under controlled conditions. A vertical olfactometer was employed to assess short-range attraction, and a dual-choice horizontal olfactometer evaluated host-seeking behaviour. Human odours were obtained from volunteers' hands, feet, and worn socks. Mosquito responses were analysed for attraction, activity, and inactivity, with statistical analysis performed using two-factor analysis of variance (ANOVA). FINDINGS: Wild An. darlingi mosquitoes showed significantly higher attraction to human odours compared to F1 mosquitoes in both the vertical and horizontal olfactometers. Wild mosquitoes were more attracted to feet and worn socks than F1 mosquitoes, which exhibited low attraction to both stimuli. The preference index (PI) was higher in wild mosquitoes for both hand and sock odours, indicating a stronger attraction to human odours. MAIN CONCLUSIONS: Wild An. darlingi mosquitoes exhibit a stronger behavioural response to human odours compared to F1 mosquitoes. The use of olfactometry, particularly vertical and horizontal methods, proved effective in studying An. darlingi mosquito's host-seeking behaviour and can be applied to further research on vector behaviour and potential control strategies.
Therapeutic potential of hookworm proteins in promoting regulatory immune responses to modulate Trypanosoma cruzi induced liver inflammation and oxidative stress.
Villar MJ, Poveda C, Zhan B … +2 more , Gonsoulin M, Jones KM
Mem Inst Oswaldo Cruz · 2026 · PMID 41711766 · Full text
BACKGROUND: Chronic Trypanosoma cruzi infection causes significant liver pathology, and current antiparasitic treatments often worsen hepatic damage. Hookworm-derived proteins have shown immunomodulatory effects in infla...
BACKGROUND: Chronic Trypanosoma cruzi infection causes significant liver pathology, and current antiparasitic treatments often worsen hepatic damage. Hookworm-derived proteins have shown immunomodulatory effects in inflammatory diseases, including T. cruzi-induced myocarditis. OBJECTIVE: This study evaluates recombinant hookworm proteins AIP-1 and AIP-2 for treating liver inflammation in a murine model of chronic Chagas disease (CD). METHODS: Female BALB/c mice infected with T. cruzi were treated with AIP-1 or AIP-2 (1 mg/kg) for seven days. Controls were untreated or received aspirin (25 mg/kg) for 14 days. Liver tissues were analyzed for parasite burden (quantitative polymerase chain reaction - qPCR), histopathology (H&E, Picrosirius Red), and cytokines (multiplex assay). Splenocytes were assessed by flow cytometry, and serum was tested for liver enzyme levels. FINDINGS: AIP-1 and AIP-2 increased hepatic interferon gamma (IFN-γ) and interleukin 10 (IL-10), decreased Nfκ-B and Stat-1, and elevated Arg1 and Nos2 expression. AIP-1 uniquely upregulated Mmp9 and Btg2. Increased splenic CD11b⁺CD11c⁺ and CD11b⁺Ly6GloLy6C⁺ cells were observed. Despite increased immune cell infiltration, parasite load and fibrosis remained unchanged, and liver enzyme levels were stable. MAIN CONCLUSION: AIP-1 and AIP-2 reduce hepatic inflammation and promote a balanced TH1/TH2 response, likely mediated by regulatory dendritic and myeloid-derived suppressor cells, supporting their potential as immunotherapeutic for T. cruzi-induced liver pathology.
First report of canine Chagas disease on the Caribbean Island of Trinidad.
Suepaul R, Mohammed A, Gottdenker NL … +6 more , Pargass I, Oura C, Ramsubhag A, Gyan L, Tripathi V, Peterson JK
Mem Inst Oswaldo Cruz · 2026 · PMID 41637258 · Full text
BACKGROUND: Chagas disease (CD) is a vector-borne infection caused by Trypanosoma cruzi, a kinetoplastid parasite of mammals. T. cruzi is transmitted by triatomine bugs throughout the Americas and some Caribbean islands....
BACKGROUND: Chagas disease (CD) is a vector-borne infection caused by Trypanosoma cruzi, a kinetoplastid parasite of mammals. T. cruzi is transmitted by triatomine bugs throughout the Americas and some Caribbean islands. On the Caribbean island of Trinidad, T. cruzi has been isolated from triatomine bugs in several residential areas where dogs are a common pet. However, canine T. cruzi infection in Trinidad has never been studied. OBJECTIVES: We aimed to demonstrate that canine CD does occur in Trinidad through a review of veterinary records from the years 2008-2023. METHODS: We reviewed 3,923 case reports from Trinidad veterinary clinics for canine Chagas cases diagnosed through histological evaluation, necropsy, blood smear evaluation, and/or polymerase chain reactions (PCR). FINDINGS: We identified 13 confirmed and two suspected canine CD cases. Animal ages ranged from five weeks to 14 years old, with four (27%) being less than one year old, including the pup of a T. cruzi-infected dam. Breed varied, although one-third (5/15) were hounds. Clinical signs ranged from asymptomatic (43%; 6/14) to severely ill with limb paresis (21%; 3/14). Seven of the fifteen (47%) dogs died, and three more (20%) were euthanized. Myocarditis with visible amastigote forms were found in two-thirds (9/15) of dogs. MAIN CONCLUSIONS: Our findings highlight a need for increased awareness of CD among dog owners and veterinarians in Trinidad.
Entomo-virological investigation in urban forest fragments and intradomiciles during a dengue outbreak in Salinas, MG, Brazil.
Oliveira CH, Teixeira TJ, Barros RMC … +11 more , Araújo AB, Ferreira AT, Chaves DCC, Campos FS, Tomé LMR, Guimarães NR, Adelino TÉR, Iani FCM, Alcantara LCJ, Araújo WS, Abreu FVS
Mem Inst Oswaldo Cruz · 2026 · PMID 41615193 · Full text
BACKGROUND: Mosquitoes (Diptera: Culicidae) are among the most important disease vectors worldwide. Several species exhibit high levels of anthropophily and are frequently found in human dwellings and forest fragments ne...
BACKGROUND: Mosquitoes (Diptera: Culicidae) are among the most important disease vectors worldwide. Several species exhibit high levels of anthropophily and are frequently found in human dwellings and forest fragments near urban areas. OBJECTIVES: In this integrative study combining mosquito collection, viral detection, and ecological analyses, the assemblage of diurnal mosquitoes was investigated across three distinct environments - intradomiciles, and two distinct urban forest fragments (UFFs) - during a dengue outbreak in the city of Salinas, Minas Gerais, Brazil. METHODS: Sampled mosquitoes were tested for the presence of dengue, Zika, and chikungunya viruses through real-time quantitative polymerase chain reaction (RT-qPCR). FINDINGS: A total of 722 mosquitoes were collected, representing seven genera and 12 species. The most abundant species were Culex quinquefasciatus (270/722, 37.4%), Aedes aegypti (205/722, 28.4%), Ae. albopictus (112/722, 15.5%), and Ae. scapularis (110/722, 15.2%). Five of 81 pools tested positive for dengue virus serotype 1 (DENV-1) RNA, all belonging to Ae. aegypti species. Phylogenetic analyses of the nearly complete genome of DENV-1 revealed clustering with strains sampled in 2023 from São Paulo State. Mosquito richness and composition differed between environments (houses and urban forests), whereas abundance was similar across all environments. MAIN CONCLUSIONS: Important vector species were detected, including Ae. aegypti, Ae. albopictus, Cx. quinquefasciatus, Ae. scapularis, Sabethes albiprivus, and Coquillettidia venezuelensis, associated with the transmission of dengue, oropouche, mayaro, yellow fever, and Venezuelan equine encephalitis viruses. Entomological and virological investigations in urban and peri-urban environments are crucial, as these areas provide shelter and refuge for anthropophilic and opportunistic mosquito species. Our findings underscore a high potential for mosquito-borne disease spillover in these areas.
Global silent transmission of the class A ß-lactamase LAP-2 by plasmid transfer and clonal expansion of Klebsiella pneumoniae lineages.
Bighi NMS, Morgado SM, Freitas FDS … +2 more , Vicente ACP, da Fonseca ÉL
Mem Inst Oswaldo Cruz · 2026 · PMID 41615094 · Publisher ↗
BACKGROUND: Narrow-spectrum antibiotics, such as narrow-spectrum β-lactams, have been pointed out as an efficient strategy to mitigate resistance and reach successful outcomes in treating enterobacterial infections. The...
BACKGROUND: Narrow-spectrum antibiotics, such as narrow-spectrum β-lactams, have been pointed out as an efficient strategy to mitigate resistance and reach successful outcomes in treating enterobacterial infections. The narrow-spectrum class A β-lactamase LAP-2, conferring resistance to narrow-spectrum cephalosporins/penicillin derivatives, is spread among Enterobacteriaceae from Asia but is rarely reported in the Americas. Due to the lack of information concerning the bla LAP-2 genetic background involved with its dissemination, this study determined the bla LAP-2 genomic environment and contextualised the LAP-2-positive Klebsiella pneumoniae strains from Brazil in the current epidemiological scenario. OBJECTIVES: This study characterised LAP-2-positive K. pneumoniae strains, focusing on their genetic environment and epidemiology. METHODS: Whole-genome sequencing and in silico analyses were performed to identify the genetic context of bla LAP-2 in five clinical isolates from Brazil. Comparative genomics and phylogenomic analysis were conducted to investigate the transmission dynamics of bla LAP-2 globally. FINDINGS: The bla LAP-2 gene was embedded in a conserved genetic module (IS3-bla LAP-2-ftsI), facilitating its dissemination among diverse Enterobacteriaceae species. The Brazilian strains harboured bla LAP-2 within a pXJ-K2 variant plasmid, a key vector in LAP-2 spread. Phylogenomic analysis revealed that, in Brazil, bla LAP-2 was carried by an ST11 K. pneumoniae lineage distinct from the Chinese lineage but globally disseminated. MAIN CONCLUSIONS: This study provides insights into the epidemiology and transmission dynamics of bla LAP-2, revealing its silent spread via plasmid transfer and clonal expansion of ST11 lineages. The high transmission potential of bla LAP-2 may compromise the application of narrow-spectrum β-lactams as a viable treatment option for enterobacteria-causing infections.
Viral metagenomics in mosquitoes as potential vectors of arboviruses in the Colombian Caribbean: characterisation of a "core" regional RNA virome.
Hoyos-López R, Echeverri-De la Hoz D, Martínez-Bravo C … +8 more , Gastelbondo-Pastrana B, Alemán-Santos M, Garay E, López Y, Contreras H, Galeano K, Arrieta G, Mattar S
Mem Inst Oswaldo Cruz · 2026 · PMID 41538522 · Full text
BACKGROUND: Mosquitoes are critical vectors in tropical regions where arboviruses like dengue and Zika are prevalent. This study focuses on characterising the RNA virome of mosquitoes in the Colombian Caribbean, emphasis...
BACKGROUND: Mosquitoes are critical vectors in tropical regions where arboviruses like dengue and Zika are prevalent. This study focuses on characterising the RNA virome of mosquitoes in the Colombian Caribbean, emphasising the core regional virome and its role in the dynamics of arboviruses. OBJECTIVES: The objective was to identify and analyse the core RNA virome of mosquitoes across different genera and seasons in the Colombian Caribbean to understand its composition and potential influence on arbovirus transmission dynamics. METHODS: In 2023, 4,074 mosquitoes from the genera Mansonia, Coquillettidia, and Anopheles were collected across Córdoba, Sucre, Bolívar, and Magdalena during rainy and dry seasons. Specimens were pooled in groups of 50, subjected to RNA extraction, and sequenced on the MGI-G50™ platform. Bioinformatic analyses utilised the DIAMOND-MEGANizer pipeline and R packages (phyloseq, vegan, ggplot2) to identify viral communities. FINDINGS: The analysis identified 22 viral families and 24 unclassified RNA viruses. The core regional virome, consistently present across species and seasons, was dominated by insect-specific viruses (ISVs) such as Aedes aegypti to virus 1 and 2, Astopletus, and Cumbaru, alongside Picornaviridae (30% of reads), Rhabdoviridae (20%), Orthomyxoviridae, and Bunyavirales. Mansonia titillans (38 species) and Coquillettidia nigricans (21 species) exhibited the highest viral richness. No significant arboviruses were detected, highlighting ISV dominance. Virome composition varied seasonally, with greater diversity in the rainy season due to increased breeding site availability and temperature. MAIN CONCLUSIONS: The stability of the core virome suggests it modulates vector competence, potentially reducing arbovirus transmission. These findings advocate the use of metagenomics for enhanced vector surveillance and biological control strategies in neotropical ecosystems.
Trypanosomatid research in Brazil: a systematic analysis of regional and temporal trends.
Marinho B, Mamede I, Martins JR … +16 more , Rodrigues A, de Melo AGB, Miranda-Junior AS, Rios Neto A, Nunes ACDS, Resende BC, Oliveira D, da Silva DO, Oliveira FGC, Duarte J, Silva LDC, Ferreira WRR, De Laet-Souza D, Macedo AM, Franco GR, Machado/ CR
Mem Inst Oswaldo Cruz · 2026 · PMID 41538521 · Full text
BACKGROUND: Trypanosomatid infections such as Chagas disease (CD) and leishmaniasis remain major public-health concerns. Brazil has a long tradition in this field, yet a consolidated, country-level view of outputs, impac...
BACKGROUND: Trypanosomatid infections such as Chagas disease (CD) and leishmaniasis remain major public-health concerns. Brazil has a long tradition in this field, yet a consolidated, country-level view of outputs, impact and collaboration patterns is useful to guide scientific policy. OBJECTIVES: To characterise Brazilian scientific production on Trypanosoma cruzi, Leishmania and Trypanosoma brucei (2010-2021), describing temporal trends, regional contributions, collaboration networks and journal impact. METHODS: We performed a bibliometric analysis of PubMed records retrieved with Medical Subject Headings (MeSH) for each pathogen/disease pair, covering publications from 1 January 2010 to 31 December 2021 (search date: 21 July 2022). Data items included article type, year, journal, author affiliations (countries/institutions) and, for Brazil, the geographical region of the corresponding author. Descriptive statistics and visualisations were generated in R. FINDINGS: From 21,713 records, 6,478 were affiliated to Brazil. Brazil contributed a substantial share of the global literature, particularly for T. cruzi (≈40%) and Leishmania (≈30%). Within Brazil, output increased over time with growing participation from the north and northeast, alongside expanding inter-institutional and international collaborations. Most publications appeared in higher-impact journals (Q1/Q2), with recent gains in Q1 outputs in historically under-represented regions. Original research predominated over reviews across the period. MAIN CONCLUSIONS: Brazilian trypanosomatid research shows sustained growth, increasing regional dispersion and rising international engagement, with a strong presence in high-impact journals. Continued support for collaborative networks and equitable funding across regions could further enhance national and global impact.
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