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Arboviruses transmitted mainly by Aedes ( Stegomyia ) aegypti and Ae. albopictus , including dengue, chikungunya, and Zika viruses, and yellow fever virus in urban settings, pose an escalating global threat. Existing risk maps, often hampered by surveillance biases, may underestimate or misrepresent the true distribution of these diseases and do not incorporate epidemiological similarities despite shared vector species. We address this by generating new global environmental suitability maps for Aedes -borne arboviruses using a multi-disease ecological niche model with a nested surveillance model fit to a dataset of over 21,000 occurrence points. This reveals a convergence in suitability around a common global distribution with recent spread of chikungunya and Zika closely aligning with areas suitable for dengue. We estimate that 5.66 (95% confidence interval 5.64-5.68) billion people live in areas suitable for dengue, chikungunya and Zika and 1.54 (1.53-1.54) billion people for yellow fever. We find large national and subnational differences in surveillance capabilities with higher income more accessible areas more likely to detect, diagnose and report viral diseases, which may have led to overestimation of risk in the United States and Europe. When combined with estimates of uncertainty, these suitability maps can be used by ministries of health to target limited surveillance and intervention resources in new strategies against these emerging threats. Arboviruses transmitted by Aedes mosquitoes have an expanding global distribution and identifying areas at risk is important for public health planning. Here, the authors present global disease maps for dengue, chikungunya, Zika and yellow fever through a multi-disease ecological niche modelling approach.

The 2015–16 Zika virus epidemic emerged in the Americas and rapidly spread throughout the region and beyond, showing the epidemic potential of this mosquito-borne Orthoflavivirus and its capacity to cause severe congenital malformations and neurological sequelae. WHO declared the Zika virus epidemic a public health emergency of international concern in 2016. Despite this declaration, there are no licensed Zika virus vaccines, therapeutics, or diagnostic tests appropriate for routine antenatal screening. To address this absence of essential tools to detect and mitigate the threat of future Zika virus outbreaks, a group of global experts developed a priority agenda for Zika virus research and development. This Series paper summarises crucial challenges and knowledge gaps and outlines a comprehensive strategy to advance research, surveillance, global capacity, policy, and investment for Zika virus preparedness and response.

Early detection of Zika virus (ZIKV) transmission within geographic regions informs implementation of community mitigation measures such as vector reduction strategies, travel advisories, enhanced surveillance among pregnant women, and possible implementation of blood and organ donor screening or deferral. Standardized, comparative assessments of ZIKV assay and testing lab performance are important to develop optimal approaches to ZIKV diagnostic testing and surveillance. We conducted an expanded blinded panel study to characterize and compare the analytical performance of fifteen diagnostic and blood screening ZIKV NAT assays, including detection among single- and multiplex assays detecting ZIKV, dengue virus (DENV) and chikungunya virus (CHIKV). A 300 member blinded panel was constructed, consisting of 11 serial half-log dilutions ranging from ~10 4 to 10 −1 genome equivalents/mL in 25 replicates each of the Tahitian Asian ZIKV isolate in ZIKV-negative human serum. Additionally, clinical samples from individuals with DENV-like syndrome or suspected ZIKV infection in Brazil were evaluated. The majority of assays demonstrated good specificity. Analytical sensitivities varied 1–2 logs, with a substantially higher limit of detection (LOD) in one outlier. Similar analytical sensitivity for ZIKV RNA detection in singleplex and multiplex assays of the Grifols and ThermoFisher tests were observed. Coefficient of Assay Efficiency (CE), calculated to characterize assays’ RNA extraction and amplification efficiency, ranged from 0.13 for the Certest VIASURE multiplex and 0.75 for the Grifols multiplex assays. In general, assays using transcription mediated amplification (TMA) technology had greater CE compared to assays using conventional PCR technology. Donor screening NAT assays were significantly more sensitive than diagnostic RT-qPCR assays, primarily attributable to higher sample input volumes. However, ideal assays to maximize sensitivity and throughput may not be a viable option in all contexts, with other factors such as cost, instrumentation, and regulatory approval status influencing assay availability and selection, particularly in resource constrained settings.

Global risk maps are an important tool for assessing the global threat of mosquito and tick-transmitted arboviral diseases. Public health officials increasingly rely on risk maps to understand the drivers of transmission, forecast spread, identify gaps in surveillance, estimate disease burden, and target and evaluate the impact of interventions. Here, we describe how current approaches to mapping arboviral diseases have become unnecessarily siloed, ignoring the strengths and weaknesses of different data types and methods. This places limits on data and model output comparability, uncertainty estimation and generalisation that limit the answers they can provide to some of the most pressing questions in arbovirus control. We argue for a new generation of risk mapping models that jointly infer risk from multiple data types. We outline how this can be achieved conceptually and show how this new framework creates opportunities to better integrate epidemiological understanding and uncertainty quantification. We advocate for more co-development of risk maps among modellers and end-users to better enable risk maps to inform public health decisions. Prospective validation of risk maps for specific applications can inform further targeted data collection and subsequent model refinement in an iterative manner. If the expanding use of arbovirus risk maps for control is to continue, methods must develop and adapt to changing questions, interventions and data availability.

Background Aedes (Stegomyia) -borne diseases are an expanding global threat, but gaps in surveillance make comprehensive and comparable risk assessments challenging. Geostatistical models combine data from multiple locations and use links with environmental and socioeconomic factors to make predictive risk maps. Here we systematically review past approaches to map risk for different Aedes -borne arboviruses from local to global scales, identifying differences and similarities in the data types, covariates, and modelling approaches used. Methods We searched on-line databases for predictive risk mapping studies for dengue, Zika, chikungunya, and yellow fever with no geographical or date restrictions. We included studies that needed to parameterise or fit their model to real-world epidemiological data and make predictions to new spatial locations of some measure of population-level risk of viral transmission (e.g. incidence, occurrence, suitability, etc.). Results We found a growing number of arbovirus risk mapping studies across all endemic regions and arboviral diseases, with a total of 176 papers published 2002–2022 with the largest increases shortly following major epidemics. Three dominant use cases emerged: (i) global maps to identify limits of transmission, estimate burden and assess impacts of future global change, (ii) regional models used to predict the spread of major epidemics between countries and (iii) national and sub-national models that use local datasets to better understand transmission dynamics to improve outbreak detection and response. Temperature and rainfall were the most popular choice of covariates (included in 50% and 40% of studies respectively) but variables such as human mobility are increasingly being included. Surprisingly, few studies (22%, 31/144) robustly tested combinations of covariates from different domains (e.g. climatic, sociodemographic, ecological, etc.) and only 49% of studies assessed predictive performance via out-of-sample validation procedures. Conclusions Here we show that approaches to map risk for different arboviruses have diversified in response to changing use cases, epidemiology and data availability. We identify key differences in mapping approaches between different arboviral diseases, discuss future research needs and outline specific recommendations for future arbovirus mapping.

Chikungunya virus (CHIKV) and O'nyong nyong virus (ONNV) are phylogenetically related alphaviruses in the Semliki Forest Virus (SFV) antigenic complex of the Togaviridae family. There are limited data on the circulation of these two viruses in Burkina Faso. The aim of our study was to assess their circulation in the country by determining seroprevalence to each of the viruses in blood donor samples and by retrospective molecular and serological testing of samples collected as part of national measles and rubella surveillance. All blood donor samples were analyzed on the Luminex platform using CHIKV and ONNV E2 antigens. Patient samples collected during national measles-rubella surveillance were screened by an initial ELISA for CHIKV IgM (CHIKjj Detect IgM ELISA) at the national laboratory. The positive samples were then analyzed by a second ELISA test for CHIKV IgM (CDC MAC-ELISA) at the reference laboratory. Finally, samples that had IgM positive results for both ELISA tests and had sufficient residual volume were tested by plaque reduction neutralization testing (PRNT) for CHIKV and ONNV. These same patient samples were also analyzed by rRT-PCR for CHIKV. Among the blood donor specimens, 55.49% of the samples were positive for alphaviruses including both CHIKV and ONNV positive samples. Among patient samples collected as part of national measles and rubella surveillance, 3.09% were IgM positive for CHIKV, including 2.5% confirmed by PRNT. PRNT failed to demonstrate any ONNV infections in these samples. No samples tested by RT-qPCR. had detectable CHIKV RNA. Our results suggest that CHIKV and ONNV have been circulating in the population of Burkina Faso and may have been confused with malaria, dengue fever or other febrile diseases such as measles or rubella. Our study underscores the necessity to enhance arbovirus surveillance systems in Burkina Faso.

In March 2009, the U.S. Food and Drug Administration licensed an inactivated Vero cell culture-derived Japanese encephalitis vaccine (JE-VC [IXIARO®]) for use in persons aged ≥17 years. In 2013, licensure was extended to include children aged ≥2 months. A previous analysis reviewed adverse events reported to the U.S. Vaccine Adverse Event Reporting System (VAERS) from May 2009 through April 2012. We reviewed adverse events reported to VAERS following JE-VC administered from May 1, 2012 through April 30, 2016. Adverse event reporting rates were calculated using 802,229 doses distributed. During the 4-year period, 119 adverse event reports were received for a reporting rate of 14.8 per 100,000 doses distributed. Nine (8%) adverse events were classified as serious for a reporting rate of 1.1 per 100,000 distributed. The most commonly reported event was hypersensitivity (n = 24; 20%) for a rate of 3.0 per 100,000 doses distributed; 1 anaphylaxis event was reported. Ten (8%) neurologic events were reported for a rate of 1.2 per 100,000 doses distributed; 2 events were classified as seizures. Sixty-three (53%) adverse events occurred after a first dose of JE-VC. Eighty (67%) adverse events occurred after administration of JE-VC with other vaccines. Eleven (9%) adverse events were reported in children; 1 was considered serious. These data continue to support the generally favorable safety profile of JE-VC. Reporting rates of adverse events were similar to those of the previous analysis. Although reporting rates of adverse events in children could not be calculated, there were low numbers of reported events in this age group. Post-licensure adverse event surveillance for this relatively new vaccine continues to be important to monitor adverse event reporting rates and identify possible rare serious events.

•Vero cell culture-derived Japanese encephalitis vaccine (JE-VC) was licensed in the US in 2009.•We reviewed adverse events reported in the U.S. for the first 3 years post-licensure.•Of 42 reported adverse events, 5 (12%) were classified as serious for a reporting rate of 1.8 per 100,000 doses distributed; there were no deaths.•These data suggest a good safety profile for JE-VC.•Post-licensure surveillance may detect rare adverse events and safety data should continue to be monitored. In March 2009, the U.S. Food and Drug Administration licensed an inactivated, Vero cell culture-derived Japanese encephalitis vaccine (JE-VC [Ixiaro]) for use in adults. The vaccine was licensed based on clinical trial safety data in 3558 JE-VC recipients. It is essential to monitor post-licensure surveillance data to evaluate the safety of JE-VC because rare adverse events may not be detected until the vaccine is administered to a larger population. We reviewed adverse events reported to the U.S. Vaccine Adverse Event Reporting System (VAERS) for adults (≥17 years) who received JE-VC from May 2009 through April 2012. Adverse event reporting rates were calculated using 275,848 JE-VC doses distributed. Over the 3 year period, 42 adverse events following vaccination with JE-VC were reported to VAERS for an overall reporting rate of 15.2 adverse events per 100,000 doses distributed. Of the 42 total reports, 5 (12%) were classified as serious for a reporting rate of 1.8 per 100,000 doses distributed; there were no deaths. Hypersensitivity reactions (N=12) were the most commonly reported type of adverse event, with a rate of 4.4 per 100,000 doses distributed; no cases of anaphylaxis were reported. Three adverse events of the central nervous system were reported (one case of encephalitis and two seizures) for a rate of 1.1 per 100,000; all occurred after receipt of JE-VC with other vaccines. These post-marketing surveillance data suggest a good safety profile for JE-VC consistent with findings from pre-licensure clinical trials. Post-licensure safety data should continue to be monitored for any evidence of rare serious or neurologic adverse events.

BackgroundHeartland virus (HRTV) was first described as a human pathogen in 2012. From 2013 to 2017, the Centers for Disease Control and Prevention (CDC) implemented a national protocol to evaluate patients for HRTV disease, better define its geographic distribution, epidemiology, and clinical characteristics, and develop diagnostic assays for this novel virus.MethodsIndividuals aged ≥12 years whose clinicians contacted state health departments or the CDC about testing for HRTV infections were screened for recent onset of fever with leukopenia and thrombocytopenia. A questionnaire was administered to collect data on demographics, risk factors, and signs and symptoms; blood samples were tested for the presence of HRTV RNA and neutralizing antibodies.ResultsOf 85 individuals enrolled and tested, 16 (19%) had evidence of acute HRTV infection, 1 (1%) had past infection, and 68 (80%) had no infection. Patients with acute HRTV disease were residents of 7 states, 12 (75%) were male, and the median age (range) was 71 (43–80) years. Illness onset occurred from April to September. The majority reported fatigue, anorexia, nausea, headache, confusion, arthralgia, or myalgia. Fourteen (88%) cases were hospitalized; 2 (13%) died. Fourteen (88%) participants reported finding a tick on themselves in the 2 weeks before illness onset. HRTV-infected individuals were significantly older (P < .001) and more likely to report an attached tick (P = .03) than uninfected individuals.ConclusionsHealth care providers should consider HRTV disease testing in patients with an acute febrile illness with either leukopenia or thrombocytopenia not explained by another condition or who were suspected to have a tickborne disease but did not improve following appropriate treatment.