Search Results (3,101)

Aedes aegypti transmits viruses to millions of people worldwide. Despite the availability of vaccines, control and monitoring of mosquitoes is mandatory, which in turn requires knowledge of microevolutionary population genetics. Genetic techniques permit the assessment of biological parameters directly linked to the epidemiological importance of the insect (polymorphism, migration, fitness). However, these techniques are costly to most health surveillance services. Even for research laboratories, genotyping and estimation of variability may be unfeasible and time consuming. We conjectured that the wing geometry of Ae. aegypti could serve as an alternative indicator of genetic variability in mosquitoes, as wing shape is a useful taxonomic marker determined by quantitative heritage. We investigated this conjecture by testing if wild Ae. aegypti populations with high genetic variability had higher wing morphological diversity than inbred colonised populations. Using wing geometric morphometrics and microsatellite DNA genotyping of some populational samples, we confirmed this conjecture. The morphological diversity index was partly correspondent with genetic variability indexes such as theta, gene diversity and alleles per locus. Our findings, although circumscribed to the populational samples studied, indicate that wing geometry may be used as a cheap and quick semi-quantitative proxy for genetic variability. Full article

Yellow fever (YF) is an infectious disease caused by the yellow fever virus (YFV), an arbovirus of the Flaviviridae family. It is transmitted through the bite of infected mosquitoes of the Culicidae family and affects both humans and non-human primates (NHPs). This study aimed to investigate the sylvatic Culicidae fauna and the occurrence of natural YFV infection in a microregion of southern Santa Catarina, Brazil, an area recently affected by a sylvatic YF outbreak. Entomological collections were conducted between January and February 2023 in five municipalities with confirmed viral circulation. Natural YFV infection was assessed using RT-LAMP. A total of 4352 female culicids were collected, representing at least 32 species, including several key sylvatic YFV vectors. Haemagogus leucocelaenus was identified in all sampled municipalities, whereas Haemagogus (Haemagogus) janthinomys Dyar, 1921, historically considered the primary vector of sylvatic YFV in Brazil, was not detected. Mosquitoes from the genera Aedes Meigen, 1818; Haemagogus Williston, 1896; Psorophora Robineau-Desvoidy, 1827; and Sabethes Robineau-Desvoidy, 1827 were tested for YFV. Only one pool, composed of Sabethes albiprivus, tested positive, yielding a minimum infection rate (MIR) of 11.6. This is the first record of natural YFV infection in Sa. albiprivus in southern Brazil, and only the third record globally, highlighting its potential role as a secondary vector in maintaining viral circulation in sylvatic environments. Based on species presence and abundance, Hg. leucocelaenus is likely to have acted as the primary YFV vector in the study area. The composition of the culicid fauna, coupled with the detection of YFV in sylvatic vectors, indicates an ongoing epidemiological risk. These findings underscore the need to strengthen entomological surveillance and expand YF vaccination coverage in affected and neighbouring regions. Full article

Chikungunya virus (CHIKV) is an alphavirus that infects dermal fibroblasts as a primary target cell during natural mosquito-borne transmission. While primary human dermal fibroblasts (hDFs) have been implicated as a key source of type I interferon (IFN-I) during CHIKV infection, the dynamics of this response and its sufficiency for antiviral protection remain incompletely understood. Here, we systematically characterize in vitro CHIKV infection of primary hDFs, evaluating the effects of single-passage viral stock origin (mammalian- vs. mosquito-propagated), donor variability, and multiplicity of infection (MOI) on infection kinetics and innate immune induction. We demonstrate that hDFs support high-titered CHIKV replication at both MOI 1 and 0.01, resulting in universal cell death by 72 hpi despite robust IFNβ transcript induction—reaching up to ~2800-fold over mock—and secretion of pro-inflammatory cytokines, including IFNα2, TNFα, IL-1β, and IL-8. Notably, IFNβ protein levels remained below 10 pg/mL under all infection conditions, revealing a disconnect between transcriptional and translational responses, suggesting CHIKV-mediated translational suppression. Pharmacological inhibition of TBK1/IKKε via amlexanox did not suppress IFNβ transcript induction at any tested concentration, suggesting that canonical PRR signaling through this node—including both RIG-I/MAVS and TLR3/TRIF pathways—is not the major driver of the observed transcriptional response. In contrast, co-inoculation with exogenous IFNβ as low as 20 pg/mL activated IFNAR signaling, robustly upregulated interferon-stimulated genes (ISGs), and fully rescued hDFs from otherwise lethal infection. Together, these findings demonstrate that CHIKV-infected hDFs mount a transcriptionally robust but translationally insufficient innate immune response and that the transcriptional response appears to operate independently of TBK1/IKKε. These results have direct implications for understanding how the skin microenvironment may modulate early CHIKV pathogenesis and suggest that paracrine IFNβ signaling from neighboring cell types may be critical for fibroblast survival during natural infection. Full article

The Aedes aegypti mosquito exhibits a critical behavioral adaptation through its oviposition strategy, laying eggs in dry and wet environments just above the water level, allowing eggs to resist desiccation and hatch only when submerged by rain. To investigate this mechanism, we developed a nonlinear dynamic model incorporating climate-driven parameters affecting egg hatching and adult emergence. Theoretical analysis revealed an imperfect pitchfork bifurcation giving rise to a phenomenon we term basin-mediated hysteresis. Unlike classical hysteresis, which relies on coexisting stable states, this mechanism results from the progressive collapse of the extinction basin boundary. As the control parameter approaches its critical value, the basin of attraction of the trivial equilibrium shrinks. Once the population establishes itself above the threshold, returning the parameter below unity does not restore extinction, leading to an irreversible transition governing population persistence. The model was validated using field data from mosquito traps in a Brazilian city, showing strong agreement with observed seasonal patterns of female captures. Parameters were optimized using the Differential Evolution algorithm, yielding high correlation between model and field data. The results demonstrate that the dual oviposition strategy underlies population persistence and seasonal peaks, providing information for planning interventions amid global arbovirus expansion. Full article

Mosquitoes are recognized as the arthropod group with the greatest vectorial capacity, and the viruses they transmit constitute a significant concern in the context of global One Health. In addition, these insects act as hosts for a wide diversity of insect-specific viruses (ISVs), which exclusively infect arthropods. Expanding knowledge of ISVs is particularly relevant, given their potential influence on arbovirus replication and their role in elucidating the evolutionary processes that shape virus–vector interactions. In this study, we report the isolation and molecular analysis of three negeviruses associated with different mosquito species of the genera Culex, Coquillettidia, Mansonia, and Ochlerotatus, collected in Belém, Pará State, in the Brazilian Amazon: Loreto virus, Wallerfield virus, and a putative new species, designated Terra firme virus. Eleven pools exhibited cellular alterations consistent with cytopathic effects in invertebrate C6/36 cells but showed no evidence of replication in vertebrate Vero cells. Notably, simultaneous infections by two or three negeviruses were detected in some mosquito pools, indicating the occurrence of multiple viral infections within individual samples. Genomic analyses revealed that the isolated strains share conserved domains with previously described isolates from other countries. Phylogenetic inferences demonstrated that the investigated strains are classified within the clades Nelorpivirus and Sandewavirus. Taken together, these findings expand the currently known diversity of the negevirus group and contribute to a more comprehensive understanding of its host range and geographic distribution. Full article

Background/Objectives: Malaria remains a major global health burden, particularly in sub-Saharan Africa, where the recent invasion and urban expansion of Anopheles stephensi are increasing transmission risk in densely populated areas. Conventional vector control strategies, including widespread insecticide application, are progressively losing efficacy due to the rapid spread of resistance. These limitations have accelerated the development of genetic control approaches aimed at either suppressing vector populations or replacing them with genetically modified mosquitoes incapable of transmitting pathogens, with the shared objective of reducing disease transmission. For population suppression strategies, an essential component is a conditional regulatory system that enables precise control of toxic or otherwise deleterious effector proteins. The most widely used platform, the tetracycline-dependent (Tet) system, modulates gene expression in response to tetracycline. However, this system can exhibit leaky expression and variable regulation, which may compromise its reliability and limit its application in certain contexts. The dihydrofolate reductase (DHFR) destabilization domain (DD) system, developed in Drosophila, offers an alternative strategy for post-translational control of protein stability. In this system, proteins fused to a destabilization domain are rapidly degraded unless stabilized by the small molecule trimethoprim (TMP), enabling tight and reversible control. In Drosophila and prior reports, this system has been associated with relatively low fitness costs, although such effects have not been systematically evaluated in mosquitoes. Before adapting this system for mosquito genetic control, it is therefore essential to assess the impact of TMP exposure on key life-history traits. Methods: Here, we assessed the effects of varying TMP concentrations on mosquito development, survival, and reproductive output. Results: Our results demonstrate that low concentrations of TMP exposure had no detectable effects on immature development, adult survival, or reproductive output under the conditions tested, supporting the implementation of the DHFR-DD system in mosquitoes. Importantly, these effects were dose-dependent, with moderate to high TMP concentrations producing measurable impacts on mosquito fitness. Conclusions: These findings provide a foundational step toward the development of more precise and reliable conditional expression systems for genetic vector control, advancing innovative strategies to mitigate malaria transmission in high-risk regions. Full article

Mosquito-borne infectious diseases remain a major challenge to public health, highlighting the need for efficient and accessible gene editing approaches. Receptor-mediated ovary transduction of cargo (ReMOT) offers an alternative to embryonic microinjection, in which P2C, an ovary-targeting peptide, enables ovarian delivery of the editing components. However, key design parameters and operational boundaries of the P2C-based ReMOT system have not been clearly defined. Here, we performed a methodological evaluation of the P2C-mediated ReMOT CRISPR/Cas9 system in Aedes aegypti. Cas9-P2C fusion proteins with different configurations were constructed and assessed through ovarian targeting assays, in vitro cleavage analyses, and in vivo gene editing experiments. Our results show that full-length Cas9-P2C fusion proteins exhibit nuclease activity and enable effective ovarian delivery. In contrast, linear truncation of the P2C peptide markedly reduced ovarian targeting, indicating a dependence on structural integrity. Using this delivery strategy, we generated kynurenine monooxygenase (KMO) edited mosquitoes, demonstrating feasibility under the conditions tested. In addition, protein injection was also associated with reduced reproductive performance, providing physiological reference for ReMOT applications. Overall, this study defines the key design parameters and operational boundaries of the P2C-based ReMOT system, providing methodological guidance for its application and optimization in future mosquito genetic studies. Full article

Dengue Hemorrhagic Fever (DHF) is a tropical infectious disease transmitted by the Aedes aegypti mosquito and exhibits seasonal patterns with periodic increases in cases throughout the year. The control of vector-borne diseases such as DHF is very important for strengthening public health resilience against climate change, in line with the Sustainable Development Goals (SDGs) for Good Health, Well-being, and Climate Action. Therefore, this study was focused on Bogor city, which experiences high rainfall and continues to face an elevated risk of DHF. The objective was to develop a time series forecasting model to predict DHF outbreaks using Singular Spectrum Analysis (SSA). This is a statistical method for identifying patterns in time series data. Lunar and Solar calendars were adopted to capture seasonal patterns and determine the optimal window length for prediction. The results showed that the Lunar calendar more accurately captured local seasonal variation related to DHF risk. Moreover, the SSA model with one component and a window length of 7 achieved the best performance with a Mean Absolute Percentage Error (MAPE) of 0.0757. The forecast accuracy decreased with longer horizons, but the model provided reliable predictions for short-term periods (approximately 1 month, i.e., up to 4 weeks ahead), which were considered useful for planning DHF mitigation. The results emphasized that the combination of SSA with appropriate calendar systems could improve the accuracy of epidemiological predictions and support vector control policymaking in tropical regions. Full article

The cost of living is rising daily, particularly in rural areas. This is due to a variety of factors, including unemployment and a lack of knowledge about available useful resources. The study meticulously documented the diverse uses of cow dung among community members of the Maungani village of the Limpopo Province, South Africa. The qualitative approach was employed to inventory the uses of cow dung in the Maungani community. The most prevalent use was as a fertilizer for vegetables such as spinach and cabbage, which are commonly cultivated in household backyards. Other significant uses included honey harvesting, paving yards, sprinkling over vegetables to deter herbivores, as a mosquito repellent, in medicinal and cosmetic applications, as a water purifier, and as a fuel source for fire. Furthermore, some respondents emphasized the importance of cow dung in biogas production, which is vital for many communities globally. The study recommended the continued use of cow dung as a fertilizer to mitigate the financial burden of costly inorganic fertilizers on peasant farmers. Further recommendations suggest that the continuous utilization of cow dung in various ways can help rural community members achieve the Sustainable Development Goals (SDGs) 1, 2, and 3. Full article

Aedes aegypti, the main urban vector of dengue fever, poses a major public health problem in Nouakchott, Mauritania. This study analyzed the host-seeking and sugar-feeding behaviors of Ae. aegypti. Mosquitoes were collected using a vacuum cleaner in four districts between December 2023 and October 2024. Biting activity on humans was studied in May 2024, exclusively in the districts of Ksar, Tevragh Zeina and Arafat, between 5:00 a.m. and 9:00 p.m. A negative binomial model was performed to analyze the effect of location and time on the human biting rate (HBR) of mosquitoes. In Nouakchott, except in the Arafat district, Ae. aegypti bites occur mainly outdoors, between 8:00 a.m. and 1:00 p.m., with a peak between 11:00 a.m. and noon (HBR = 20 bites/person), and between 5:00 p.m. and 7:00 p.m., with a peak between 6:00 p.m. and 7:00 p.m. (HBR = 11 bites/person). Inside homes, Ae. aegypti biting activity remains low everywhere (HBR ≤ 1.5 bites/person/hour). Molecular analysis of the origin of the blood meals showed that the females collected in Nouakchott were exclusively anthropophilic. Molecular analysis of the sugar sources revealed a great diversity with sweet potato being among the most common. These results highlight the need for targeted outdoor interventions and larval control measures to reduce the risk of dengue transmission in Nouakchott. Full article

Alphaviruses are mosquito-borne viruses that can infect the central nervous system (CNS) and cause encephalomyelitis, which is a rare but dangerous complication from infection. In mice, this can be studied in a model of infection with Sindbis virus (SINV), which infects neurons and causes neurological disease. Due to the non-renewable nature of neurons, the immune response in the CNS is specialized to prevent neuronal damage or death, even if they are infected. Therefore, insights into the nuances of antiviral immunity in the CNS provide a better understanding of disease pathogenesis and mechanisms of recovery. Type I interferons (IFNs) are critically important for survival; they are an innate antiviral defense mechanism that consists mainly of IFNα and IFNβ. Although both use the same receptor, type-specific differences between IFNα and IFNβ have been described in other contexts. To this end, Ifnb^−/− mice were used to elucidate the role of IFNβ in recovery from alphavirus encephalomyelitis. IFNβ-deficient mice have intact IFNα expression and downstream signaling, but symptomatic disease occurs earlier and is more severe. This is accompanied by increased virus replication in the early stages of infection. Microgliosis is reduced in Ifnb^−/− mice compared to wildtype, but inflammatory cytokine/chemokine levels are higher and associated with alterations in monocyte and NK cell recruitment into the CNS. Ifnb^−/− mice have no deficiencies in the expression of factors known to be required for viral clearance. Therefore, IFNβ modulates the early stages of the immune response and facilitates restriction of virus replication, contributing to delayed disease onset. Full article

Background: Dengue fever is one of the most common mosquito-borne viral infections, with severe cases characterized by plasma leakage, hemorrhage, and multi-organ involvement. Identification of dengue serotypes and reliable biomarkers is essential for predicting disease progression and guiding timely interventions. Methods: This prospective cohort study was conducted at a super-speciality tertiary care hospital in southern India from July 2024 to July 2025. A total of 69 patients presenting with dengue warning signs were included in the study. Patients were categorized into the severe dengue group (n = 25) and non severe dengue group (n = 44). Clinical data, laboratory findings, dengue serotype, and serial serum samples collected on Days 1, 4, and 8 were analyzed to evaluate the predictive and monitoring efficacy of Interleukin-6 (IL-6) and Interleukin-8 (IL-8), and followed up till discharge. Results: Out of 69 dengue patients with warning signs, 32 dengue-positive patients were serotyped, which included DEN V-1 (31.3%), DEN V-2 (31.3%), DEN V-3 (15.6%), DEN V-4 (18.8%), and mixed DEN V-(2 + 3) (3.1%). Severe dengue patients exhibited a higher frequency of secondary dengue infection (IgG) than primary dengue infection (88% vs. 12%), with statistically significantly higher packed cell volume, hemoglobin levels, high AST levels, and prolonged activated partial thromboplastin time, as well as lower platelet counts and albumin levels. Platelet transfusion was given to 35 dengue patients, which had also resulted in significant length of stay in hospital in comparison to non-transfused patients. IL-6 and IL-8 levels were significantly elevated in severe dengue patients when compared to non-severe dengue patients on Day 1 and Day 4, followed by a decline on Day 8, corresponding with clinical recovery. However, the elevated IL-8 levels were observed to be significantly associated with longer hospital stays, indicating its potential role as an early predictor of disease progression. Conclusions: The observed co-circulation of multiple serotypes reflects the hyper-endemic pattern reported across India. Early measurement of these cytokines IL-6 and IL-8 helps distinguish severe from non-severe dengue among patients presenting with warning signs. IL-6 and IL-8 may have potential as biomarkers for disease severity. However their role in guiding platelet transfusion requires further investigation in non-severe cases and prioritizing timely management for those at higher risk of severe disease. Full article

Urban coastal wetlands constitute important ecological interfaces where human activities, wildlife, and arthropod vectors interact, potentially increasing the risk of pathogen transmission. In the city of Veracruz, Mexico, several interdunal lagoons have been incorporated into urban areas and are intensively used for recreational activities; however, information on their mosquito fauna remains limited. This study aimed to characterize mosquito species composition, abundance, and diversity in three urban recreational interdunal lagoons in Veracruz. Adult mosquitoes were collected weekly during the rainy season (June–September) 2023 using CDC light traps. Specimens were identified based on morphological characters using standard taxonomic keys, including genitalia dissections for male specimens when necessary. Species richness, sampling completeness, and community structure were evaluated using non-parametric richness estimators, diversity indices, species accumulation curves, and similarity analyses. A total of 1465 adult mosquitoes belonging to 11 species and five genera were collected. Mosquito assemblages were characterized by low species richness and a marked dominance of Culex panocossa and Culex quinquefasciatus across all lagoons. Diversity indices were low, and species composition showed a high degree of similarity among sites. Notably, Uranotaenia apicalis was recorded for the first time in the state of Veracruz, expanding its known geographical distribution. These findings indicate that urban interdunal lagoons support simplified mosquito communities dominated by disturbance-tolerant species, highlighting their potential epidemiological relevance and the need for targeted vector surveillance in urban coastal environments. Full article

Yellow fever (YF) remains a re-emerging vector-borne zoonotic disease in tropical regions of the Americas despite the availability of an effective vaccine. In South America, the virus is maintained through a jungle transmission cycle involving Haemagogus and Sabethes mosquitoes and non-human primates (NHPs), which act as amplifying hosts and key epidemiological sentinels. This narrative review examines the current status of YF epizootics in South America, with a focus on the role of NHPs in viral circulation, early detection, and spillover risk to human populations. We synthesize recent evidence on epizootic patterns across endemic countries, the differential susceptibility of neotropical primates, and the ecological and environmental drivers influencing transmission, including deforestation, habitat fragmentation, and human encroachment into forested areas. In addition, we analyze current surveillance strategies, including wildlife monitoring, entomological and genomic surveillance, and their integration within a One Health framework. This review highlights that YF epizootics are expanding geographically and are closely linked to environmental change and human–ecosystem interactions. Strengthening integrated, multidisciplinary surveillance systems is essential to improve early detection, guide vaccination strategies, and prevent human outbreaks. These findings underscore the critical importance of operationalizing the One Health approach to enhance preparedness and response to YF in South America. Full article

Getah virus (GETV), a mosquito-borne virus capable of infecting multiple economically important animal species, poses a potential epidemic risk. In May 2024, one pig farm from Heyuan, Guangdong Province, China, suffered reproductive disorders in sows and diarrhea in newborn piglets. Out of the six blood samples that were collected, three tested strongly positive for GETV, yielding a positivity rate of 50%. Moreover, a GETV strain (designated GDHYLC2024) was successfully isolated and identified. The viral titer of GDHYLC2024 was 10^7.687 TCID₅₀/mL in Vero cells. Its genome was composed of 11,688 bases in length. Interestingly, compared with GDHYLC23, it had no unique 32-nucleotide repeat insertion in 3′ non-coding region. However, phylogenetic analysis showed that GDHYLC2024 and GDHYLC23 clustered in genotype III. Animal infection experiments demonstrated that the GDHYLC2024 strain was highly pathogenic to 4-day-old piglets, which caused obvious clinical symptoms including fever, depression, anorexia, periorbital edema, ataxia, and three deaths out of a total of five individuals in the infection group. This study reported re-emergence of GETV in the same region of Guangdong Province, China. The above findings suggest that GETV continuously poses a threat to farm pig’s health and has genetic diversity. Full article