Search Results (635)

Dengue, Zika, yellow fever, chikungunya, and Mayaro arboviruses represent an increasing threat to public health because of the serious infections they cause annually in many countries. Serological diagnosis of these viruses is challenging, making the development of new diagnostic strategies imperative. In this study, we investigated the effectiveness of gold nanorods (GNRs) functionalized with specific anti-dengue and anti-orthoflavivirus antibodies in detecting viral particles. GNRs were created with a length-to-width ratio of up to 5.5, a size of 71.4 ± 6.5 nm, and a light absorption peak at 927 nm, and they were treated with 4 mM polyethyleneimine. These GNRs were attached to a small amount of monoclonal antibodies that target flaviviruses, and the viral particles were detected by measuring the localized surface plasmon resonance using an UV-Vis/NIR spectrometer. The tests found Orthoflavivirus dengue and Orthoflavivirus zikaense in diluted human serum and ground-up mosquitoes, with the lowest detectable amount being 100 PFU/mL. The GNRs described in this study can be used to enhance flavivirus diagnostic tests or to develop new, faster, and more accurate diagnostic techniques. Additionally, the functionalized GNRs presented here are promising for supporting virological surveillance studies in mosquitoes. Our findings highlight a fast and highly sensitive method for detecting Orthoflavivirus in both human and mosquito samples, with a detection limit as low as 100 PFU/mL. Full article

Background: Arthropod-borne diseases primarily affect tropical and subtropical regions, exhibiting seasonal patterns that peak during hot and rainy months when conditions favor mosquito vector proliferation. Factors such as high temperatures, elevated humidity, rainfall, urbanization, and the abundance of natural and artificial breeding sites influence Aedes vector dynamics. In this context, arboviruses pose significant public health challenges, likely worsened by global warming. In Brazil, Aedes (Stegomyia) aegypti (Linnaeus, 1762) is the primary vector for yellow fever, dengue, chikungunya, and Zika. Aedes (Stegomyia) albopictus (Skuse, 1894) is an important global arbovirus vector and is considered a potential vector in Brazil. Entomological surveillance of these species often uses oviposition traps targeting immature stages. Evaluating studies that use ovitraps to collect Ae. aegypti and Ae. albopictus egg is essential for improving mosquito surveillance strategies. This study systematically reviewed peer-reviewed articles on ovitrap-based surveillance of Aedes mosquitoes in Brazil, published in Portuguese and English from 2012 to 2022. The findings suggest that ovitraps are an effective method for detecting the presence or absence of Ae. aegypti and Ae. albopictus, serving as a reliable proxy for estimating mosquito abundance in Brazilian contexts. Full article

Background: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyperinflammatory syndrome that may be triggered by infections such as dengue virus. Due to overlapping features with severe dengue and sepsis, diagnosis of HLH in dengue-infected patients remains challenging. Methods: We conducted a narrative review and individual patient data meta-analysis of published cases of dengue-associated HLH. Eligible studies were identified through a search of PubMed and Scopus databases up to 5 March 2025. Clinical, laboratory, microbiological, treatment, and outcome data were extracted and analyzed. Results: A total of 133 patients from 71 studies were included. The median patient age was 18 years, and 56.8% were male. Common clinical features included fever (96.9%), cytopenias, organomegaly, and liver dysfunction. ALT elevation, jaundice, and hypofibrinogenemia were associated with mortality. DENV-1 was the most common serotype (57.4%) and was negatively associated with death. Overall, 19.3% of patients died. Multivariate analysis did not identify independent mortality predictors. Conclusions: Dengue-associated HLH predominantly affects young individuals and carries significant mortality. Key indicators of poor prognosis include hepatic dysfunction and the presence of shock or organ failure. Early recognition and prompt immunomodulatory treatment, particularly corticosteroids, may improve outcomes. Full article

The mosquito Aedes aegypti is the vector responsible for the transmission of important arboviruses such as dengue fever, Chikungunya, Zika virus, and yellow fever. These diseases affect millions of people and exert impacts on healthcare systems throughout the world. Given the increasing resistance to synthetic insecticides, essential oils from plants constitute an ecologically viable alternative for the control of this vector. The aim of the present study was to investigate the larvicidal activity of the essential oil (EO), aqueous extract, rutin, and hydrolate from the leaves of Myrciaria floribunda against Aedes aegypti larvae in the initial L4 stage. The yield of EO was 0.47%. Thirty-seven chemical constituents were identified and quantified using chromatographic methods. The major constituents were (E)-caryophyllene (27.35%), 1,8-cineole (11.25%), β-selinene (4.92%), and α-muurolene (4.92%). In the larvicidal tests, the lethal concentration (LC₅₀) was 201.73 ppm for the essential oil, 15.85% for the aqueous extract, and 22.46 ppm for rutin. The hydrolate had no larvicidal activity. The compounds that exhibited larvicidal activity against Aedes aegypti constitute a promising option for the development of natural formulations to diminish the propagation of this vector. Full article

(1) Background: Murine typhus, caused by Rickettsia typhi, is a neglected rickettsial disease and an underdiagnosed cause of acute febrile illness (AFI), particularly in endemic regions such as Indonesia. (2) Case description: We report a case series of four patients presenting with AFI of less than seven days in duration. Three patients were admitted with moderate disease, while one presented with septic shock with the macrophage activation-like syndrome (MALS) phenotype. Common clinical features included myalgia and headache; additional symptoms included cough, sore throat, and abdominal pain. Laboratory findings revealed bicytopenia, elevated transaminases, and raised inflammatory and bacterial infection markers. Common tropical infections—dengue, typhoid fever, and leptospirosis—and other potential sources of infection were excluded early during hospitalization. Diagnosis was confirmed by nucleic acid amplification testing (NAAT), which detected R. typhi in all patients. Doxycycline was initiated following confirmation, leading to defervescence within 36–48 h. (3) Conclusions: Murine typhus remains an underrecognized cause of febrile illness in Indonesia. In the near future, the inclusion of rickettsial testing in the diagnostic protocol of AFI will be crucial, as it enables timely administration of effective, low-cost treatment. Full article

In this paper, the authors introduce the transmuted geometric integer-valued autoregressive model with periodicity, designed specifically to analyze epidemiological and public health time series data. The model uses a transmuted geometric distribution as a marginal distribution of the process. It also captures varying tail behaviors seen in disease case counts and health data. Key statistical properties of the process, such as conditional mean, conditional variance, etc., are derived, along with estimation techniques like conditional least squares and conditional maximum likelihood. The ability to provide k-step-ahead forecasts makes this approach valuable for identifying disease trends and planning interventions. Monte Carlo simulation studies confirm the accuracy and reliability of the estimation methods. The effectiveness of the proposed model is analyzed using three real-world public health datasets: weekly reported cases of Legionnaires’ disease, syphilis, and dengue fever. Full article

Arboviruses are a growing concern in many nations. Several reports of arboviral outbreaks have been recorded globally in the past decade alone. Repeated arboviral outbreaks in developing countries have consistently highlighted vulnerabilities in disease surveillance and response systems, exposing critical gaps in early detection, contact tracing, and resource allocation. The 2024 Dengue fever outbreak in Ghana, which recorded 205 confirmed cases out of 1410 suspected cases, underscored the urgent need to evaluate the country’s preparedness for arboviral outbreaks, given the detection of competent vectors in the country. A retrospective analysis of Ghana’s 2009–2013 pandemic influenza response plan revealed significant deficiencies in emergency preparedness, raising concerns about the country’s ability to manage emerging arboviral threats. This review assessed Ghana’s current arboviral outbreak response and preparedness by examining (a) the effectiveness of vector control measures, (b) the role of early warning systems in mitigating outbreaks, (c) laboratory support and diagnostic capabilities, and (d) community engagement strategies. It highlights the successes made in previous outbreaks and sheds light on several gaps in Ghana’s outbreak response efforts. This review also provides recommendations that can be implemented in many countries across Africa as they brace themselves for any arboviral outbreak. Full article

Background: The evaluation of antiviral or vaccination strategies for the prevention of dengue infections in a traveler population would require extensive and complex studies. This prospective study aimed to identify a cohort of dengue naïve participants living in Medellín, a dengue endemic area, as a proxy for travelers and to determine the incidence of primary dengue virus (DENV) infection (symptomatic and asymptomatic) in this cohort. In Colombia, epidemic dengue waves occur every 3–4 years, with infected Aedes mosquitoes present in ~80% of the territory, including Medellín. Methods: Participants > 16 years of age, living in Medellín, were screened for anti-DENV immunoglobulin G (IgG). DENV seronegative participants were enrolled in this study. A serological anti-DENV survey was performed, with semiannual sample collections for up to 2 years. Acute DENV infections were evaluated by monitoring fever and testing for DENV nonstructural protein 1 and/or RNA. Results: Of the 4885 screened participants, 3008 participants (62%) were DENV seronegative and enrolled. Among them, 2263 (75%) completed this study, and 2644 (88%) had at least one serosurvey visit after baseline. Of those, 52 (2%) had laboratory-confirmed DENV seroconversion, and 19 (<1%) had febrile illness, but none had laboratory-confirmed DENV infection. Conclusions: This study identified a cohort of predominantly students, seronegative at study start, living in Medellín and serving as a proxy for a prospective DENV infection traveler population. Laboratory-confirmed primary DENV infection was found in 2% of participants, with <1% reporting febrile illnesses, meeting the WHO criteria for probable clinical dengue cases. Full article

The objective was to conduct a review and meta-analysis of questionnaire-based surveys of dengue knowledge, attitudes, perceptions, and practices (KAP)s among the general public in Sri Lanka as no prior island-wide survey existed. The electronic database PubMed and other bibliography were searched for literature on dengue questionnaire-based KAP surveys in Sri Lanka from 2000–2023. Data pertaining to the three domains were extracted from sixteen eligible articles, pooled, and analyzed separately using random effect models. Meta-analyses of the three domains were performed using R version 3.6.3. The population surveyed (8955) was <0.045% of the total Sri Lankan population. The publication frequency increased over time and surveys were distributed in Colombo and suburbs 43.7% (7/16), Kandy 25% (4/16,) Gampaha 12.5% (2/16), and 6.3% (1/16) one each in Kurunegala, Matara, Batticaloa, and Jaffna. Knowledge on dengue transmission, vector breeding, and fever as a symptom was >80%, while on vector species, preferred feeding times, recurrence of dengue it was > 55% and on warning signs of severity it was 25%. Attitudes towards community participation in dengue prevention activities and knowledge of dengue risk factors (avoidance of aspirin and dark colored drinks) were poor, while practice of control measures (removal of water collecting receptacles, roof-gutter management) lacked regularity. Full article

Orthoflaviviruses (formerly flaviviruses) are known for their role in numerous diseases affecting both humans and animals. Despite the worldwide distribution of orthoflaviviruses, individual species are only found in endemic or epidemic regions. However, in recent decades, certain orthoflaviviruses have spread beyond their traditional geographic boundaries, even crossing continents. Given the long-distance movements of birds, the knowledge of zoonotic orthoflaviviruses associated with birds is essential because of their possible introduction into new regions, as was the case with West Nile virus and Usutu virus. A thorough literature review was conducted on zoonotic orthoflaviviruses related to birds, including lesser-known (re-)emerging and neglected orthoflaviviruses that are limited to specific regions and/or avian hosts but have the potential to spread to a wider geographical area and pose a higher risk of transmission to humans. Several of these viruses possess significant zoonotic potential and can cause a wide spectrum of diseases in humans, ranging from mild febrile illnesses (Zika virus) to severe neuroinvasive diseases (tick-borne encephalitis, West Nile, Japanese encephalitis virus) and hemorrhagic fevers (yellow fever, dengue virus). Geographic distribution, hosts, vectors, incidence of human infections, and impact on human and animal health of zoonotic flaviviruses related to birds are critically reviewed. The viruses have been categorized based on the role of birds as an orthoflavivirus host and the clinical presentation in human infections. Full article

Dengue fever remains a major global health threat, and mathematical models are crucial for predicting its spread and evaluating control strategies. This study introduces a highly flexible dengue transmission model using a novel piecewise fractional derivative framework, which can capture abrupt changes in epidemic dynamics, such as those caused by public health interventions or seasonal shifts. We conduct a rigorous comparative analysis of four widely used but distinct mechanisms of disease transmission (incidence rates): Harmonic Mean, Holling Type II, Beddington–DeAngelis, and Crowley–Martin. The model’s well-posedness is established, and the basic reproduction number (${\Re }_0$) is derived for each incidence function. Our central finding is that the choice of this mathematical mechanism critically alters predictions. For example, models that account for behavioral changes (Beddington–DeAngelis, Crowley–Martin) identify different key drivers of transmission compared to simpler models. Sensitivity analysis reveals that vector mortality is the most influential control parameter in these more realistic models. These results underscore that accurately representing transmission behavior is essential for reliable epidemic forecasting and for designing effective, targeted intervention strategies. Full article

Dengue virus (DENV) infection is strongly associated with dengue hemorrhagic fever and dengue shock syndrome, both of which carry mortality risks. Addressing the urgent need for effective dengue therapeutics, we identified sofalcone, a gastroprotective agent with antioxidant and anti-inflammatory properties, as a potential inhibitor of DENV replication. Sofalcone demonstrated efficacy against all four DENV serotypes, with the dose inhibiting 50% (IC50) value of 28.1 ± 0.42 μM against viral replication of DENV serotype 2, without significant cytotoxicity. Additionally, sofalcone significantly improved survival rates and reduced viral titers in DENV-infected ICR-suckling mice. Mechanistically, sofalcone induced heme oxygenase-1 (HO-1) expression via the nuclear factor-erythroid 2-reated factor 2 (Nrf2) pathway, which in turn suppressed viral protease activity and restored antiviral interferon (IFN) responses. This included dose-dependent stimulation of IFN downstream antiviral genes such as 2′-5′-oligoadenylate synthetase 1 (OAS1), OAS2, and OAS3. Given its established clinical use as an anti-gastric ulcer drug, sofalcone offers promising potential for rapid application in treating DENV infection. Full article

Background: Dengue is a global health concern, with half of the world’s population at risk and no antiviral treatment available. This Phase 0 study investigated dengue infections among household contacts (HHCs) of dengue index cases (ICs) and assessed the feasibility of conducting a Phase 2 trial for a novel antiviral. Methods: Participants were enrolled in Nha Trang, Vietnam, from April 2022 to February 2023. Dengue ICs were identified within 72 h of fever onset, and their healthy adult HHCs enrolled within 48 h. Blood samples and questionnaires were collected bi-weekly for four weeks, with a follow-up visit on day 40. DENV RT-qPCR, NS1, and anti-DENV IgM/IgG ELISAs were performed. Results: Overall, 130 dengue ICs and 301 HHCs were enrolled, with 91.7% (276/301) completing all follow-up visits. Baseline anti-DENV IgG showed prior dengue infections in 262/301 HHCs (87.0%). Fifty HHCs were excluded from the HHC infection analysis based on evidence of a DENV infection (viral load [VL], NS1, IgM, and IgG results) at enrollment. During follow-up, 2.0% of HHCs (5/251) had DENV infections based on virological parameters (DENV RNA and/or NS1 positivity), and anti-DENV IgG/IgM seroconversion was detected in 7.2% (18/251). Conclusions: This study demonstrated the operational feasibility of a dengue IC-HHC design for a Phase 2 trial. Full article

Research on the spread of dengue fever is typically measured periodically, producing longitudinally structured data. The varying coefficient model for longitudinal data allows the coefficient to vary as a smooth function of time. The data in this study have a longitudinal structure that offers a long-term presentation of dengue fever in Bandung City, Indonesia, influenced by a set of covariates that vary over time and space. The former are temperature, rainfall, and humidity, and the latter is residential location, such as vector index and population density. Considering space- and time-varying effects, a space-time varying coefficient model was proposed. The model parameters were estimated by minimizing the P-splines quantile objective function. The results implemented on the data show that the model and method satisfy the condition of the data, which means the coefficients vary over space and time. Based on the three quantile levels, each subdistrict in Bandung City has a different level of incidence rate category. Due to differences in covariate effects both over time and over space, Bandung City also exhibits a heterogeneous incidence rate pattern based on its three quantile levels. The result provides a quantile pattern that can be used as a guide for high-performance dengue fever classification. Full article