Improved Mosquito Housing and Saliva Collection Method Enhances Safety While Facilitating Longitudinal Assessment of Individual Mosquito Vector Competence for Arboviruses.

Background: Assessing the potential for mosquitoes to transmit medically important arboviruses is essential for understanding their threat to human populations. Currently, vector competence studies are typically performed by collecting saliva using a glass capillary tube system which involves sacrificing the mosquito at the time of saliva collection allowing only a single data point. These techniques also require handling infected mosquitoes and glass capillaries, constituting a safety risk. Materials and Methods: To improve the efficiency and safety of assessing vector competence, a novel containment and saliva collection approach for individually housed mosquitoes was developed. The improved housing, allowing longitudinal tracking of individual mosquitoes, consists of a 12-well Corning polystyrene plate sealed with a three-dimensional printed lid that holds organdy netting firmly against the rims of the wells. Results: This method provides excellent mosquito survival for five species of mosquitoes, with at least 79% of each species tested surviving for more than 2 weeks, comparable to the carton survival rates of ≥76%. When the plate housing system was used to assess vector infection, replication of West Nile virus (WNV) in mosquito tissues was similar to traditional containment mosquito housing. Mosquito saliva was collected using either blotting paper pads or traditional glass capillaries to assay viral transmission. The blotting paper collection showed similar or better sensitivity than the capillary method; in addition, longitudinal saliva samples could be collected from individual mosquitoes housed in the 12-well plates. Conclusions: The improved housing and saliva collection technique described herein provides a safer and more informative method for determining vector competence in mosquitoes.

Assessment of wing geometric morphometrics of urban Culex quinquefasciatus (Diptera: Culicidae) populations.

Culex quinquefasciatus is a cosmopolitan species distributed throughout tropical and subtropical areas of the world. The species is of great epidemiological importance as it is responsible for vectoring the causative agent of lymphatic filariasis and several arboviruses, including West Nile virus. Wing geometric morphometrics has been widely used to assess phenotypic variations in mosquito species. Here, we hypothesize that Cx. quinquefasciatus populations in urban parks in the city of São Paulo, Brazil, have been subjected to anthropogenic selective pressures that are responsible for driving their ecology and behavior. Mosquitoes were collected by CDC traps in five municipal parks in the city of São Paulo. Eighteen anatomical landmark coordinates on each female right wing were digitized. Canonical variate analysis, wireframe graphs, cross-validated reclassification tests and the neighbor-joining method were used to assess phenotypical dissimilarity in wing shape between populations. Centroid size was calculated to assess differences in wing size between populations, which can result from different environmental conditions during immature mosquito development. Moderately heterogeneous wing shape and wing size patterns were found in the populations analyzed, indicating that selective pressures in the urban environment are affecting the wing patterns of Cx. quinquefasciatus populations in the city of São Paulo, Brazil.

Nucleic Acid Preservation Card Surveillance Is Effective for Monitoring Arbovirus Transmission on Crocodile Farms and Provides a One Health Benefit to Northern Australia.

The Kunjin strain of West Nile virus (WNVKUN) is a mosquito-transmitted flavivirus that can infect farmed saltwater crocodiles in Australia and cause skin lesions that devalue the hides of harvested animals. We implemented a surveillance system using honey-baited nucleic acid preservation cards to monitor WNVKUN and another endemic flavivirus pathogen, Murray Valley encephalitis virus (MVEV), on crocodile farms in northern Australia. The traps were set between February 2018 and July 2020 on three crocodile farms in Darwin (Northern Territory) and one in Cairns (North Queensland) at fortnightly intervals with reduced trapping during the winter months. WNVKUN RNA was detected on all three crocodile farms near Darwin, predominantly between March and May of each year. Two of the NT crocodile farms also yielded the detection of MVE viral RNA sporadically spread between April and November in 2018 and 2020. In contrast, no viral RNA was detected on crocodile farms in Cairns during the entire trapping period. The detection of WNVKUN and MVEV transmission by FTATM cards on farms in the Northern Territory generally correlated with the detection of their transmission to sentinel chicken flocks in nearby localities around Darwin as part of a separate public health surveillance program. While no isolates of WNVKUN or MVEV were obtained from mosquitoes collected on Darwin crocodile farms immediately following the FTATM card detections, we did isolate another flavivirus, Kokobera virus (KOKV), from Culex annulirostris mosquitoes. Our studies support the use of the FTATM card system as a sensitive and accurate method to monitor the transmission of WNVKUN and other arboviruses on crocodile farms to enable the timely implementation of mosquito control measures. Our detection of MVEV transmission and isolation of KOKV from mosquitoes also warrants further investigation of their potential role in causing diseases in crocodiles and highlights a "One Health" issue concerning arbovirus transmission to crocodile farm workers. In this context, the introduction of FTATM cards onto crocodile farms appears to provide an additional surveillance tool to detect arbovirus transmission in the Darwin region, allowing for a more timely intervention of vector control by relevant authorities.

Decomposition of socioeconomic inequalities in arboviral diseases in Brazil and Colombia (2007-2017).

BACKGROUND: We used surveillance data from Brazil and Colombia during 2007-2017 to assess the presence of socioeconomic inequalities on dengue, chikungunya and Zika at the neighborhood level in two Latin American cities. METHODS: To quantify the inequality, we estimated and decomposed the relative concentration index of inequality (RCI) accounting for the spatiotemporal distribution of the diseases. RESULTS: There were 281 426 arboviral cases notified in Fortaleza, Brazil, and 40 889 in Medellin, Colombia. The RCI indicated greater concentration of dengue cases among people living in low socioeconomic settings in both sites. The RCIs for chikungunya in Fortaleza covered the line of equality during their introduction in 2014, while the RCIs for Zika and chikungunya in Medellin indicated the presence of a small inequality. The RCI decomposition showed that year of notification and age were the main contributors to this inequality. In Medellin, the RCI decomposition showed that age and access to waste management accounted for 75.5%, 72.2% and 54.5% of the overall inequality towards the poor for dengue, chikungunya and Zika, respectively. CONCLUSIONS: Our study presents estimates of the socioeconomic inequality of arboviruses and its decomposition in two Latin American cities. We corroborate the concentration of arboviral diseases in low socioeconomic neighborhoods and identify that year of occurrence, age, presence of healthcare facilities and waste management are key determinants of the heterogenous distribution of endemic arboviruses across the socioeconomic spectrum.

Determinants of Aedes mosquito density as an indicator of arbovirus transmission risk in three sites affected by co-circulation of globally spreading arboviruses in Colombia, Ecuador and Argentina.

BACKGROUND: The global impact of Zika virus in Latin America has drawn renewed attention to circulating mosquito-borne viruses in this region, such as dengue and chikungunya. Our objective was to assess socio-ecological factors associated with Aedes mosquito vector density as a measure of arbovirus transmission risk in three cities of potentially recent Zika virus introduction: Ibagué, Colombia; Manta, Ecuador; and Posadas, Argentina, in order to inform disease mitigation strategies. METHODS: We sampled Aedes mosquito populations in a total of 1086 households, using indoor and peridomestic mosquito collection methods, including light traps, resting traps, traps equipped with chemical attractant and aspirators. For each sampled household, we collected socio-economic data using structured questionnaires and data on microenvironmental conditions using iButton data loggers. RESULTS: A total of 3230 female Aedes mosquitoes were collected, of which 99.8% were Aedes aegypti and 0.2% were Aedes albopictus. Mean female Aedes mosquito density per household was 1.71 (standard deviation: 2.84). We used mixed-effects generalized linear Poisson regression analyses to identify predictors of Aedes density, using month, neighborhood and country as random-effects variables. Across study sites, the number of household occupants [incidence rate ratio (IRR): 1.08, 95% confidence interval (CI): 1.01-1.14], presence of entry points for mosquitoes into the household (IRR: 1.51, 95% CI: 1.30-1.76) and presence of decorative vegetation (IRR: 1.52, 95% CI: 1.22-1.88) were associated with higher Aedes density; while being in the highest wealth tertile of household wealth (IRR: 0.78, 95% CI: 0.66-0.92), knowledge of how arboviruses are transmitted (IRR: 0.94, 95% CI: 0.89-1.00) and regular emptying of water containers by occupants (IRR: 0.79, 95% CI: 0.67-0.92) were associated with lower Aedes density. CONCLUSIONS: Our study addresses the complexities of arbovirus vectors of global significance at the interface between human and mosquito populations. Our results point to several predictors of Aedes mosquito vector density in countries with co-circulation of multiple Aedes-borne viruses, and point to modifiable risk factors that may be useful for disease prevention and control.

Spatial Distribution and Burden of Emerging Arboviruses in French Guiana.

Despite the health, social and economic impact of arboviruses in French Guiana, very little is known about the extent to which infection burden is shared between individuals. We conducted a large multiplexed serological survey among 2697 individuals from June to October 2017. All serum samples were tested for IgG antibodies against DENV, CHIKV, ZIKV and MAYV using a recombinant antigen-based microsphere immunoassay with a subset further evaluated through anti-ZIKV microneutralization tests. The overall DENV seroprevalence was estimated at 73.1% (70.6-75.4) in the whole territory with estimations by serotype at 68.9% for DENV-1, 38.8% for DENV-2, 42.3% for DENV-3, and 56.1% for DENV-4. The overall seroprevalence of CHIKV, ZIKV and MAYV antibodies was 20.3% (17.7-23.1), 23.3% (20.9-25.9) and 3.3% (2.7-4.1), respectively. We provide a consistent overview of the burden of emerging arboviruses in French Guiana, with useful findings for risk mapping, future prevention and control programs. The majority of the population remains susceptible to CHIKV and ZIKV, which could potentially facilitate the risk of further re-emergences. Our results underscore the need to strengthen MAYV surveillance in order to rapidly detect any substantial changes in MAYV circulation patterns.

Towards a better integration of social sciences in arbovirus research and decision-making: an experience from scientific collaboration between Cuban and Quebec institutions.

In 2017, the Institute of Tropical Medicine Pedro Kourí, University of Montreal Public Health Research Institute, and McGill University joined efforts to provide scenarios for scientific exchange and knowledge dissemination about the social science contribution on arboviral research. This commentary describes the scientific collaboration between Cuban and Canadian (Quebec) institutions, illustrating the need and opportunities to facilitate research and effective decision-making processes for arboviral prevention and control, going beyond traditional biomedical aspects. We organized a set of scientific activities within three international events conducted in Cuba between 2017 and 2018. Given the collaborating institutions' expertise and the knowledge gaps in arboviral research, we selected three main thematic areas: social determinants and equity, community-based interventions and use of evidence for decision-making. The partnership shows that interdisciplinary collaboration and the use and integration of quantitative and qualitative methods from the social sciences is essential to face the current challenges in arbovirus research.

Performance of Eastern Mediterranean Region laboratories in the World Health Organization external quality assessment programme for arbovirus diagnostics.

BACKGROUND: Arboviruses such as dengue virus, yellow fever virus, Zika virus and chikungunya virus are major threats to human health globally, including countries in the Eastern Mediterranean Region (EMR). AIMS: This study aimed to assess laboratory proficiency in EMR countries for detection of dengue virus, yellow fever virus, Zika virus and chikungunya virus. METHODS: A global external quality assessment programme for arbovirus diagnostics was developed and run in 2016 and 2018. National-level public health laboratories were instructed to apply the polymerase chain reaction detection method on specimen panels containing dengue virus, yellow fever virus, Zika virus and chikungunya virus. RESULTS: Over both rounds of the programme, 100% of participating EMR laboratories correctly detected yellow fever virus and chikungunya virus, ≥ 84.6% detected dengue fever virus and ≥ 76.9% detected Zika virus. CONCLUSION: While participating EMR countries demonstrated good proficiency in detecting arboviruses, only half of them were enrolled in the global external quality assessment programme, providing an incomplete picture of regional capacity. Effort should be put into increasing participation in subsequent rounds.

Performance of Eastern Mediterranean Region laboratories in the World Health Organization external quality assessment programme for arbovirus diagnostics

Background: Arboviruses such as dengue virus, yellow fever virus, Zika virus and chikungunya virus are major threats to human health globally, including countries in the Eastern Mediterranean Region (EMR).Aims: This study aimed to assess laboratory proficiency in EMR countries for detection of dengue virus, yellow fever virus, Zika virus and chikungunya virus.Methods: A global external quality assessment programme for arbovirus diagnostics was developed and run in 2016 and 2018. National-level public health laboratories were instructed to apply the polymerase chain reaction detection method on specimen panels containing dengue virus, yellow fever virus, Zika virus and chikungunya virus.Results: Over both rounds of the programme, 100% of participating EMR laboratories correctly detected yellow fever virus and chikungunya virus, ≥ 84.6% detected dengue fever virus and ≥ 76.9% detected Zika virus. Conclusion: While participating EMR countries demonstrated good proficiency in detecting arboviruses, only half of them were enrolled in the global external quality assessment programme, providing an incomplete picture of regional capacity. Effort should be put into increasing participation in subsequent rounds.

Contexte : Les arbovirus tels que le virus de la dengue, le virus de la fièvre jaune, le virus Zika et le virus chikungunya constituent des menaces majeures pour la santé humaine dans le monde, y compris dans les pays de la Région de la Méditerranée orientale. Objectifs : La présente étude visait à évaluer l’aptitude des laboratoires dans les pays de la Région pour la détection des virus susmentionnés. Méthodes : Un programme mondial d’évaluation externe de la qualité pour le diagnostic des arbovirus a été mis au point et adopté en 2016 et 2018. Les laboratoires de santé publique nationaux ont reçu l’instruction d’appliquer la méthode de détection par amplification génique sur des panels d’échantillons de laboratoires contenant le virus de la dengue, le virus de la fièvre jaune, le virus Zika et le virus chikungunya. Résultats : Au cours des deux cycles du programme, 100 % des laboratoires participants de la Région de la Méditerranéenne orientale ont correctement détecté le virus de la fièvre jaune et le virus du chikungunya, un pourcentage supérieur ou égal à 84,6 % ont détecté le virus de la dengue et un pourcentage supérieur ou égal à 76,9 % de ces laboratoires ont détecté le virus Zika. Conclusions : Alors que les pays participants de la Région de la Méditerranée orientale ont démontré une bonne maîtrise de la détection des arbovirus, seulement la moitié d’entre eux étaient inscrits au programme mondial d’évaluation externe de la qualité, fournissant une image incomplète de la capacité régionale. Des efforts devraient être déployés pour accroître la participation aux cycles suivants.

Entomological Assessment of the Status and Risk of Mosquito-borne Arboviral Transmission in Ghana.

Entomological surveillance is one of the tools used in monitoring and controlling vector-borne diseases. However, the use of entomological surveillance for arboviral infection vector control is often dependent on finding infected individuals. Although this method may suffice in highly endemic areas, it is not as effective in controlling the spread of diseases in low endemic and non-endemic areas. In this study, we examined the efficiency of using entomological markers to assess the status and risk of arbovirus infection in Ghana, which is considered a non-endemic country, by combining mosquito surveillance with virus isolation and detection. This study reports the presence of cryptic species of mosquitoes in Ghana, demonstrating the need to combine morphological identification and molecular techniques in mosquito surveillance. Furthermore, although no medically important viruses were detected, the importance of insect-specific viruses in understanding virus evolution and arbovirus transmission is discussed. This study reports the first mutualistic relationship between dengue virus and the double-stranded RNA Aedes aegypti totivirus. Finally, this study discusses the complexity of the virome of Aedes and Culex mosquitoes and its implication for arbovirus transmission.

A review of the economic evidence of Aedes-borne arboviruses and Aedes-borne arboviral disease prevention and control strategies.

Introduction:Aedes-borne arboviruses contributes substantially to the disease and cost burden.Areas covered: We performed a systematic review of the economic evidence surrounding aedes-borne arboviruses and strategies to prevent and control these diseases to inform disease control policy decisions and research directions. We searched four databases covering an 18-year period (2000-2018) to identify arboviral disease-related cost of illness studies, cost studies of vector control and prevention strategies, cost-effectiveness analyses and cost-benefit analyses. We identified 74 published studies that revealed substantial global total costs in yellow fever virus and dengue virus ranging from 2.1 to 57.3 billion USD. Cost studies of vector control and surveillance programs are limited, but a few studies found that costs of vector control programs ranged from 5.62 to 73.5 million USD. Cost-effectiveness evidence was limited across Aedes-borne diseases, but generally found targeted dengue vaccination programs cost-effective. This review revealed insufficient economic evidence for vaccine introduction and implementation of surveillance and vector control programs.Expert opinion: Evidence of the economic burden of aedes-borne arboviruses and the economic impact of strategies for arboviral disease prevention and control is critical to inform policy decisions and to secure continued financial support for these preventive and control measures.

Building Laboratory-Based Arbovirus Sentinel Surveillance Capacity During an Ongoing Dengue Outbreak, Burkina Faso, 2017.

In West Africa, identification of nonmalarial acute febrile illness (AFI) etiologic pathogens is challenging, given limited epidemiologic surveillance and laboratory testing, including for AFI caused by arboviruses. Consequently, public health action to prevent, detect, and respond to outbreaks is constrained, as experienced during dengue outbreaks in several African countries. We describe the successful implementation of laboratory-based arbovirus sentinel surveillance during a dengue outbreak in Burkina Faso during fall 2017. We describe implementation, surveillance methods, and associated costs of enhanced surveillance during an outbreak response as an effort to build capacity to better understand the burden of disease caused by arboviruses in Burkina Faso. The system improved on existing routine surveillance through an improved case report form, systematic testing of specimens, and linking patient information with laboratory results through a data management system. Lessons learned will improve arbovirus surveillance in Burkina Faso and will contribute to enhancing global health security in the region. Elements critical to the success of this intervention include responding to a specific and urgent request by the government of Burkina Faso and building on existing systems and infrastructure already supported by CDC's global health security program.

Vaccine Demand and Willingness-to-pay for Arbovirus Vaccines: A Cross-sectional Survey in Rural Guatemala.

BACKGROUND: Arboviruses including dengue (DENV), chikungunya (CHIKV) and Zika cause significant morbidity in Latin America. With multiple arbovirus vaccines in development, better understanding of community attitudes and acceptability for these vaccines is needed. METHODS: In September 2016, a cross-sectional survey assessed arbovirus knowledge, attitudes, vaccine demand and willingness-to-pay (WTP) at the conclusion of a DENV/norovirus surveillance study in rural Guatemala with high arbovirus endemicity. Factors associated with vaccine demand and WTP were assessed with regression analysis. RESULTS: Among 564 surveyed households, DENV knowledge was high. There was great concern for arboviruses, particularly CHIKV. Overall vaccine attitudes were positive with <5% identifying significant barriers, hesitancy or refusing previous vaccination. At 50% and 75% efficacy, 75% and 88% of respondents wanted arbovirus vaccines, respectively. DENV vaccine demand at 50% efficacy was associated with increased housing density, nonhealth postvaccination location, older children and medical source for information. For each vaccine, 52-55% of respondents were WTP $0-$3.40, while 16-17% were WTP ≥$6.81. WTP at $3.40 and $6.81 levels for all vaccines was associated positively with parental education but negatively with good DENV knowledge. History of purchasing and identifying barriers to vaccines was associated with WTP ≥$6.81. CONCLUSIONS: Demand for potential DENV, CHIKV and Zika vaccines is high at 50% and 75% efficacy in this Guatemalan community. Associated factors could be leveraged to optimize arbovirus vaccine implementation. Overall low WTP given current cost of Dengvaxia (Sanofi Pasteur, Lyon, France) suggests that government subsidization may be necessary in resource-poor regions, though a small private market may be supported.

External quality assessment for arbovirus diagnostics in the World Health Organization Western Pacific Region, 2013-2016: improving laboratory quality over the years.

Arboviruses continue to pose serious public health threats in the World Health Organization (WHO) Western Pacific Region. As such, laboratories need to be equipped for their accurate detection. In 2011, to ensure test proficiency, the WHO Regional Office for the Western Pacific piloted an external quality assessment (EQA) programme for arbovirus diagnostics. By 2016, it had grown into a global programme with participation of 96 laboratories worldwide, including 25 laboratories from 19 countries, territories and areas in the Region. The test performance of the 25 laboratories in the Region in 2016 was high with 23 (92%) reporting correct results in all specimens for dengue and chikungunya viruses. For Zika virus, 18 (72%) of the 25 laboratories reported correct results in all specimens, while seven (28%) demonstrated at least one error. When comparing iterations of this EQA programme in the Region between 2013 and 2016, the number of participating laboratories increased from 18 to 25. The first round only included dengue virus, while the latest round additionally included chikungunya, Zika and yellow fever viruses. Proficiency for molecular detection of dengue virus remained high (83-94%) over the four-year period. The observed proficiency for arbovirus diagnostics between 2013 and 2016 is an indicator of laboratory quality improvement in the Region.