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The pathway of Instituto Oswaldo Cruz (IOC) runs parallel with the astonishing series of events in the 20th century, which might be viewed as a dispute between hope and ideological belief. As a centennial organisation the IOC has witnessed the same set of events and perhaps experienced some of them, but in most cases, it has been unable to influence or deter them. Since its beginnings the IOC has been engaged in addressing public health challenges and either by serendipitous findings or by the scientific inquiry it has brought some Res Novae and ignited sparks of hope that one day most of the infectious diseases that proliferate in Brazil might be controlled. In this perspective essay to introduce the series of articles in celebration of the 125th Anniversary of the IOC I will sketch an overview of its journey in the context of some 20th century events through a quarter of a century time frame.
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. 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. 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). 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. 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.
Triatoma dimidiata is a widely distributed vector of Trypanosoma cruzi in Mesoamerica, but its epidemiological role in most regions of Panamá remains poorly understood. To investigate the presence, infection status, and feeding behaviour of T. dimidiata populations in peridomestic areas of Palmira Arriba, western Panamá. 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. 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. 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.
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. To assess the risk of CD transmission by evaluating triatomine presence and infection rates in households across Iquitos and nearby communities. 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). 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]. 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.
Chagas disease (CD) is caused by Trypanosoma cruzi. Treatment is based on benznidazole (Bz), although it has significant limitations, such as low efficacy in the chronic phase. Therefore, the search for new therapies with greater selectivity and antiparasitic activity is necessary. In this context, 1,2,4-oxadiazole stands out for its biological properties, including antiparasitic activities. To evaluate the in vitro activity of N-cyclohexyl 3-(3-methylphenyl)-1,2,4-oxadiazol-5-amine derivatives against the Y strain of T. cruzi and an in vivo toxicity study. Cytotoxicity was evaluated in LLC-MK2 cells by the MTT assay, while the antiparasitic effect on the three T. cruzi life forms was determined by counting. Flow cytometry analyses were then conducted to investigate possible death pathway mechanisms and antioxidant and antiacetylcholinesterase activities. Scanning electron microscopy (SEM) was also performed to observe morphological changes caused by the compounds. Finally, in vivo acute toxicity tests were performed on ZebraFish embryos. The results presented show distinct cellular toxicity profiles in LLC-MK2 cells, in addition to demonstrating antiparasitic activity at different concentrations. In amastigotes, cytotoxic effects were stimulated. The molecules also induced an increase in reactive oxygen species and membrane damage, in addition to loss of integrity and morphological changes. The antioxidant activity revealed a high capacity for scavenging free radicals, suggesting an alteration of the redox balance of the parasite, in addition to showing inhibition of acetylcholinesterase, an important enzyme present in the formation of parasites, which choline is a constituent. In the ZebraFish model, molecule 2a showed dose-dependent embryonic toxicity, with an LC50 of 14-15 µM. The calculated conclusions appear to indicate an antiparasitic effect associated with cell death mechanisms. However, further studies are needed to reduce toxicity in the animal model and increase delivery to the site of action.
Persistent reinfestation of Triatoma infestans in the Gran Chaco undermines Chagas disease (CD) control. While insecticide resistance is a known factor, the fine-scale social and demographic structure of vector colonies remains poorly understood. To analyse the micro-geographic genetic structure, mating systems, and demographic history of T. infestans in a rural community in the Bolivian Chaco. We genotyped 381 individuals from three neighbouring structures (domiciliary and peridomestic) using eight highly polymorphic microsatellite loci (expected heterozygosity, HE = 0.675). Genealogical relationships were reconstructed using maximum likelihood (ML) analysis (COLONY), and demographic history was inferred through heterozygosity tests. The infestation comprised 42 distinct full-sibling families nested within a single colony. We observed a stark dichotomy: two dominant families (> 80 individuals) exhibited monogamy and signs of distinct demographic histories (one in expansion, one recovering from a bottleneck), while 40 minor families showed high promiscuity (polygyny/polyandry). Finite growth rates varied significantly (λ = 1.03 vs 1.22), evidencing active intra-colonial competition. Domestic populations are not random aggregates, but complex mosaics of coexisting lineages with different adaptive strategies. The dominance of monogamous families suggests a priority effect advantage, while the "tail" of promiscuous minor families represents a cryptic reservoir. Effective control must account for this structural resilience, as surviving minor lineages could rapidly recolonise the niche.
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. This study evaluates recombinant hookworm proteins AIP-1 and AIP-2 for treating liver inflammation in a murine model of chronic Chagas disease (CD). 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. 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. 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.
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. We aimed to demonstrate that canine CD does occur in Trinidad through a review of veterinary records from the years 2008-2023. 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). 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. Our findings highlight a need for increased awareness of CD among dog owners and veterinarians in Trinidad.
Parasitic diseases may increase the risk of metabolic abnormalities through persistent inflammation. However, the effects of a hyperglycaemic diet during Trypanosoma cruzi infection remain poorly understood. This study aimed to investigate the metabolic, parasitological, immunological, and histological effects of a hyperglycaemic diet during acute T. cruzi infection in mice. C57BL/6 mice were divided into four groups: non-infected with standard diet (NISD), infected with a standard diet (ISD), non-infected with hyperglycaemic diet (NIHD), and infected with hyperglycaemic diet (IHD). Animals were fed their respective diets for eight weeks prior to infection and monitored up to 30 days post-infection (DPI) for blood glucose, body mass, biochemical markers, parasitaemia, tissue alterations, and immune cell profiles. At the time of infection, hyperglycaemic diet groups showed higher blood glucose and body mass. By 30 DPI, these animals exhibited lower glucose, increased parasitaemia, adipose tissue hypertrophy, and reduced cholesterol levels compared with controls. Infected groups showed an increased CD4+ IFN-γ+ T cells at 10 DPI, whereas macrophage expansion was observed only in ISD mice. Cardiac parasitism was higher at 30 DPI than at 10 DPI. These results show that T. cruzi infection affects metabolic parameters and that a hyperglycaemic diet worsens parasitological outcomes during the acute phase of infection and appears to downregulate the immune response.
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. To conduct entomological surveillance and molecular detection of YFV and other Orthoflavivirus species in mosquito samples collected from affected and potentially receptive areas. 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. 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. 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.
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. In this work we focused on pathogenic genes to further characterise the transcriptomic dynamics accompanying the nutrient restriction within the insect-dwelling parasite stage. 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. 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). 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.
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. 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. Sampled mosquitoes were tested for the presence of dengue, Zika, and chikungunya viruses through real-time quantitative polymerase chain reaction (RT-qPCR). 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. 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.
Arboviruses represent a potential threat to global public health due to their ability to infect various vertebrate hosts and vectors, as well as their adaptability to diverse ecosystems, allowing them to expand geographically across continents. The present study aimed to describe the molecular epidemiology of encephalitic arboviruses, including Venezuelan equine encephalitis virus (VEEV), Eastern equine encephalitis virus (EEEV), Western equine encephalitis virus (WEEV), West Nile virus (WNV), Saint Louis encephalitis virus (SLEV), Toscana virus (TOSV), and Rift Valley fever virus (RVFV) in nervous tissue samples from domestic and wild animals from the Northern region of Brazil, between February 2023 and June 2024. Samples negative for rabies virus were analysed by reverse transcription real-time polymerase chain reaction (RT-qPCR) targeting Alphavirus, Orthoflavivirus and Phlebovirus species.Positive samples were subjected to viral isolation in cell culture and whole-genome sequencing using next-generation sequencing.Phylogenetic and molecular clock analyses were performed to characterise viral lineages and evolutionary relationships. Two samples tested positive for arboviruses by RT-qPCR: one SLEV sample from the state of Amazonas, which showed a low viral load, preventing virus isolation and sequencing, and one Madariaga virus (MADV) sample from the state of Pará, which could be isolated and sequenced.The isolated agent belongs to lineage III of EEEV, showing most similarity to strains from Guyana and Argentina. The present study detected two arboviruses in animals, suggesting its circulation in the study area.
The protozoan Trypanosoma cruzi causes Chagas disease (CD). There are two drugs available for the treatment with limited efficacy, especially in the later stage. Focusing on drug repurposing by virtual screening of chemical databases, butoconazole (BTZ) was identified as promising hit. Our aim was to explore the trypanosomicidal effect of BTZ alone or in combination with benznidazole (BZ) against T. cruzi. Our in vitro assays validated the low cytotoxicity of BTZ and high potency on amastigotes (EC50 = 0.07 μM), being 24-fold more potent than BZ. Washout assays demonstrated the sterilisation capacity of BTZ, whereas its combination with BZ gave an additive interaction (xƩFICI = 0.66). In a mouse model of acute T. cruzi infection, BTZ was unable to suppress parasitaemia but ensured the animal survival. BTZ plus BZ reduced parasitaemia and provided higher survival rates than monotherapies. However, quantitative polymerase chain reaction (qPCR) revealed that BTZ + BZ protocol gave 100% of lack of parasitological cure, as parasite satDNA was amplified in the heart of all surviving animals. Our dataset reinforces the relevance of drug repurposing and combination strategies to advance into the development of novel therapeutic approaches for CD.
Benznidazole (BZN) has been used for more than fifty years in the treatment of Chagas disease (CD). It is produced by only three pharmaceutical companies worldwide: Lafepe (Brazil); Elea (Argentina) and Liconsa (Spain). The therapeutic interchangeability among these products has never been evaluated. To assess bioequivalence between three 100 mg BZN formulations. Pharmaceutical equivalence, with dissolution testing, was assessed prior to the bioequivalence study. For bioequivalence, healthy adult participants received 100 mg of BZN formulations after meal, in a randomised clinical trial. Blood BZN concentrations were measured. Pharmacokinetic parameters were determined by non-compartmental analysis. The BZN Liconsa demonstrated faster in vitro dissolution. However, bioavailability was not different between formulations. The mean area under the curve (AUC)84h values were 49431.22 h*ng/mL (SD = 9938.53) to Lafepe, 48974.38 h*ng/mL (SD = 10304.67) to Elea and 48204.17 h*ng/mL (SD = 9342.18) to Liconsa. The mean Cmax values were 2339.23 ng/mL (SD = 445.53) for Lafepe, 2209.04 ng/mL (SD = 448.02) for Elea and 2303.90 ng/mL (SD = 431.41) for Liconsa. The mean tmax was not different between formulations. AUC were higher in women for Elea (20%) and Lafepe (27%). The adverse events did not differ between sexes. The 100 mg BZN formulations demonstrated bioequivalence.
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. 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. 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. 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. 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.
Chagas disease (CD) and Leishmaniasis, caused by Trypanosoma cruzi and Leishmania species, are treated with outdated drugs that are toxic and have limited efficacy. New therapeutic alternatives are therefore needed. Natural products are valuable scaffolds for drug discovery, and Asteraceae species exhibit microbicidal activity. This study evaluated the antiparasitic activity and selectivity of two Asteraceae species, Chromolaena hookeriana and Campuloclinium macrocephalum, against trypanosomatids. C. hookeriana and C. macrocephalum extracts were profiled by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), and their cytotoxicity and antiparasitic activity were evaluated against multiple forms and strains of T. cruzi and Leishmania amazonensis (L. amazonensis) in 2D and 3D cultures. UHPLC-MS/MS revealed predominantly pentacyclic triterpenoids in C. macrocephalum, including ursolic and oleanolic acids (negative mode) and lupeol derivatives (positive mode). C. macrocephalum was more effective than Benznidazole (Bz) (EC50 = 1.17 vs 4.47 µg/mL) against epimastigotes and nine times more potent against trypomastigotes (EC50 = 0.38 vs 3.5 µg/mL). Both extracts matched Bz activity on intracellular T. cruzi but exhibited time-dependent cytotoxicity. They also showed similar effectiveness to miltefosine (Mt) against L. amazonensis amastigotes (EC50 = 0.36-0.70 µg/mL). The chemical profile supports the stronger antiparasitic activity of C. macrocephalum, likely linked to triterpenoids, and highlights Asteraceae extracts as promising candidates for drug discovery against neglected tropical diseases (NTDs).
Sand flies (Diptera: Psychodidae) are well-known vectors of Leishmania, yet their associations with other trypanosomatids remain poorly understood. Expanding knowledge on these interactions is essential to elucidate the ecological diversity of parasites circulating in natural and periurban environments. To characterise sand fly species composition and assess the diversity of trypanosomatids naturally infecting sand flies in the Serra do Cipó district, Minas Gerais, Brazil. Sand flies were collected between 2023 and 2025 in the Mata da Tapera and nine surrounding peridomestic sites using Centre for Disease Control light trap (CDC-LT) and a Shannon trap. Females were examined by midgut dissection and screened individually for trypanosomatids using nested polymerase chain reaction (PCR) targeting the 18S rRNA V7-V8 region, followed by sequencing and phylogenetic analyses. A total of 1,460 sand flies representing 21 species were collected, with Pintomyia pessoai (35.5%) being the most abundant. No flagellates were observed in 105 dissected females. Molecular screening of 730 females revealed 12 positives (overall positivity = 1.6%), including Leishmania infantum in Pi. pessoai, Pi. christenseni, and Pa. barretoi; L. braziliensis in Pi. monticola; and non-Leishmania taxa such as Herpetomonas samuelpessoai, Novymonas esmeraldas, a representative of Strigomonadinae, Trypanosoma sp. (Anura clade), and a lineage related to Sergeia. These findings confirm the circulation of Leishmania in Serra do Cipó while revealing hidden trypanosomatid diversity spanning at least five genera. The results suggest that sand flies may act as ecological "hubs", transiently interacting with multiple parasite lineages beyond the classical Leishmania cycle, highlighting the need to broaden the ecological perspective in sand fly-parasite studies.
Phlebotomine sand flies are hematophagous vectors of major human pathogens, including Leishmania spp., with blood ingestion essential for reproduction and vector competence. Accurate quantification of blood meal volume is crucial for understanding physiological processes and transmission dynamics. Here, we introduce a novel, non-destructive image-based method to estimate blood intake in Lutzomyia longipalpis, the principal vector of Leishmania infantum in the Americas. High-resolution images of unfed and blood-fed females were analysed using Fiji ImageJ (open-source software) when several morphometric parameters were measured and validated against biochemical haemoglobin (Hb) quantification. Blood-fed females exhibited a 56.6% increase in abdominal width and a shift toward a rounded body shape, which was strongly correlated with a visible transilluminated abdominal area (R² = 0.92). Some parameters, such as mean grey value and abdominal length, showed a low to moderate correlation with Hb content (R < 0.60). However, the correlation with abdominal area and width was R ≈ 0.90, indicating those are reliable parameters that can be used to estimate blood intake by Lu. longipalpis females. Unlike spectrophotometric methods, this approach preserves specimen integrity, which, in theory, enables longitudinal studies on physiology and host-parasite interactions. This methodology offers a reliable, scalable, and cost-effective alternative for estimating blood meal.
Dengue outbreaks pose a significant public health risk in Suriname, with challenges in mosquito surveillance and limited data on insecticide resistance hampering control efforts. To investigate the resistance status and involved mechanisms of Aedes aegypti mosquitoes for malathion and λ-cyhalothrin insecticides. The Centres for Disease Control and Prevention (CDC) bottle bioassay was used to test the resistance phenotypic status of Ae. aegypti while the occurrence and frequency of knockdown resistance (kdr) mutations were accessed by TaqMan genotype assays for the sites 410L (Valine/Leucine), 1016I (Valine/Isoleucine), and 1534C (Phenylalanine/Cysteine). Results showed resistance to malathion in the Blauwgrond population, with other regions exhibiting reduced susceptibility based on mortality rates between 89% and 94%. Very low mortality rates indicate resistance to λ-cyhalothrin in all tested areas. Knockdown resistance (kdr) mutations were detected at high frequencies. The triple homozygous kdr genotype leucine/leucine, isoleucine/isoleucine, cysteine/cysteine (LL/II/CC) predominated (84.2%), while the wild-type genotype was found only in 1.8% of the samples. This study reports the first detection of malathion resistance in Ae. aegypti from Suriname and confirms high levels of resistance to λ-cyhalothrin, possibly driven by kdr gene mutations. The results emphasise the importance of sustained surveillance and continued research on resistance mechanisms to guide effective and evidence-based vector control strategies.