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Objective To study dengue vector breeding patterns under a variety of conditions in public and private spaces; to explore the ecological, biological and social (eco-bio-social) factors involved in vector breeding and viral transmission, and to define the main implications for vector control. Methods In each of six Asian cities or periurban areas, a team randomly selected urban clusters for conducting standardized household surveys, neighbourhood background surveys and entomological surveys. They collected information on vector breeding sites, people's knowledge, attitudes and practices surrounding dengue, and the characteristics of the study areas. AII premises were inspected; larval indices were used to quantify vector breeding sites, and pupal counts were used to identify productive water container types and as a proxy measure for adult vector abundance. Findings The most productive vector breeding sites were outdoor water containers, particularly if uncovered, beneath shrubbery and unused for at least one week. Peridomestic and intradomestic areas were much more important for pupal production than commercial and public spaces other than schools and religious facilities. A complex but non-significant association was found between water supply and pupal counts, and lack of waste disposal services was associated with higher vector abundance in only one site. Greater knowledge about dengue and its transmission was associated with lower mosquito breeding and production. Vector control measures (mainly larviciding in one site) substantially reduced larval and pupal counts and 'pushed' mosquito breeding to alternative containers. Conclusion Vector breeding and the production of adult Aedes aegypti are influenced by a complex interplay of factors. Thus, to achieve effective vector management, a public health response beyond routine larviciding or focal spraying is essential. Objectif Etudier les schemas de reproduction des vecteurs de la dengue dans diverses conditions et dans des espaces publics et prives, rechercher les facteurs ecologiques, biologiques et sociaux impliques dans la reproduction de ces vecteurs et la transmission virale et determiner les principales implications pour la lutte antivectorielle. Methodes Dans six grandes villes ou zones periurbaines d'Asie, une equipe a selectionne au hasard des groupes urbains pour mener des enquetes aupres des rnenages standardisees, des enquetes de voisinage et des enquetes entomologiques. Les equipes ont recueilli des informations sur les sites de reproduction des vecteurs, les connaissances des habitants, les attitudes et les pratiques a propos de la dengue et les caracteristiques des zones etudiees. Tous les lieux ont ete inspectes; les equipes ont utilise les indices larvaires pour evaluer sur le plan quantitatif les sites de reproduction vectorielle et le decompte des pupes pour identifier les types d'objets renfermant de l'eau les plus productifs et pour servir de mesure indirecte de l'abondance des vecteurs adultes. Resultats Les sites de reproduction les plus productifs etaient les objets renfermant de I'eau situes a I'exterieur, en particulier lorsqu'ils etaient depourvus de couvercle, sous des broussailles et inutilises pendant au moins une semaine. Les zones peridornestiques et intradornestiques jouaient un role beaucoup plus important dans la production de pupes que les espaces commerciaux et publics autres que les ecoles et les edifices religieux. Une association complexe, mais non significative, a ete relevee entre l'approvisionnement en eau et le nombre de pupes decomptees et on a constate un lien entre le manque de services d'elimination des dechets et une plus grande abondance des vecteurs sur un site seulement. La presence de meilleures connaissances sur la dengue et sa transmission chez les habitants etait egalement associee une reproduction et a une production plus limitees des vecteurs. Les mesures de lutte antivectorielle (principalement I'application de larvicide sur le site) ont permis de reduire substantiellement les nin de larves et de pupes eta <> la reproduction des moustiques vers d'autres recipients. Conclusion Un ensemble interactif complexe de facteurs influe sur la reproduction et la production de moustiques Aedes aegypti adultes. Ainsi, pour gerer efficacement les populations vectorielles, une reponse de sante publique globale, allant au-dela des traitements larvicides de routine ou de la pulverisation focale, est indispensable. Objetivo Estudiar las caracteristicas de la reproduccion del vector del dengue en diversas condiciones en espacios publicos y privados; investigar los aspectos ecologicos, biologicos y sociales (ecobiosociales) que intervienen en la reproduccion del vector y la transmision del virus, y determinar las principales implicaciones para la lucha antivectorial. Metodos En cada una de las seis zonas urbanas o periurbanas de Asia estudiadas, un equipo selecciono al azar conglomerados urbanos para realizar encuestas de hogares normalizadas, encuestas basales del vecindario y estudios entomologicos. Reunieron informacion sobre los criaderos de vectores, los conocimientos de la gente al respecto, las actitudes y practicas relacionadas con el dengue, y las caracteristicas de las zonas estudiadas. Se inspeccionaron todos los locales, y se usaron los indices larvarios para cuantificar los criaderos del vector, y el numero de pupas para distinguir el tipo de contenedores de agua productivos y como indicador sustitutivo de la abundancia de vectores adultos. Resultados Los criaderos de vectores mas productivos fueron los contenedores de agua situados al aire libre, sobre todo los que estaban sin cubrir o debajo de arbustos, y los que no habian sido utilizados por lo menos en una semana. Las areas peridomesticas e intradomesticas contribuian a la produccion de pupas mucho mas que los espacios comerciales y publicos, exceptuando las escuelas y los centros religiosos. Se observo una relacion compleja aunque no significativa entre el suministro de agua y el numero de pupas, y la falta de servicios de evacuacion de desechos se asocio a una mayor abundancia de vectores en un solo sitio. La posesion de mayores conocimientos sobre el dengue y su transmision se asocio a una menor reproduccion y produccion de'mosquitos. Las medidas de lucha antivectorial (principalmente la aplicacion de larvicidas en un sitio) lograron reducir sustancialmente el numero de larvas y pupas y los criaderos de mosquitos hacia otros contenedores. Conclusion La reproduccion del vector y la produccion de Aedes aegypti adulto dependen de una compleja interaccion de factores. En consecuencia, para lograr controlar eficazmente los vectores, es fundamental articular una respuesta de salud publica que no se limite a la aplicacion de larvicidas o el rociamiento localizado., Introduction Dengue, which is the fastest re-emerging arboviral disease in the world, imposes a heavy economic and health burden on countries, families and individual patients. (1,2) In the absence of [...]

Background: Wolbachia is an endosymbiont bacterium generally found in about 40% of insects, including mosquitoes, but it is absent in Aedes aegypti which is an important vector of several arboviral diseasesdengue, chikungunya, zika, and yellow fever. The evidence that Wolbachia trans-infected Ae. aegypti mosquitoes lost their vectorial competence and became less capable of transmitting arboviruses to human hosts highlights the potential of using Wolbachia-based approaches for prevention and control of arboviral diseases. Recently, release of Wolbachia trans-infected Ae. aegypti has been deployed widely in many countries for the control of mosquito-borne viral diseases. Field surveillance and monitoring of Wolbachia presence in released mosquitoes is important for the success of these control programs. So far, a number of studies have reported the development of loop mediated isothermal amplification (LAMP) assays to detect Wolbachia in mosquitoes, but the methods still have some specificity and cost issues. Methodology/Principal findings: We describe here the development of a LAMP assay combined with the DNA strand displacement-based electrochemical sensor (BIOSENSOR) method to detect wAlbB Wolbachia in trans-infected Ae. aegypti. Our developed LAMP primers used a low-cost dye detecting system and 4 oligo nucleotide primers which can reduce the cost of analysis while the specificity is comparable to the previous methods. The detection capacity of our LAMP technique was 1.4 nM and the detection limit reduced to 2.2 fM when combined with the BIOSENSOR. Our study demonstrates that a BIOSENSOR can also be applied as a stand-alone method for detecting Wolbachia; and it showed high sensitivity when used with the crude DNA extracts of macerated mosquito samples without DNA purification. Conclusions/Significance: Our results suggest that both LAMP and BIOSENSOR, either used in combination or stand-alone, are robust and sensitive. The methods have good potential for routine detection of Wolbachia in mosquitoes during field surveillance and monitoring of Wolbachia-based release programs, especially in countries with limited resources. Author summary: Mosquito-borne diseases such as dengue, chikungunya, zika, and yellow fever are transmitted to humans mainly by the bites of Aedes aegypti mosquitoes. Controlling the vectors of these diseases relies mostly on the use of insecticides. However, the efficiency has been reduced through the development of insecticide resistance in mosquitoes. Wolbachia is an endosymbiotic bacterium that is naturally found in 40% of insects, including mosquitoes. The bacterium can protect its insect hosts from viral infections and can also cause sterility in insect host populations, therefore, providing an opportunity to use it for human disease control. Application of a Wolbachia trans-infected mosquitoes needs simple, rapid and sensitive methods for detecting the bacteria in released mosquitoes. In this paper, we develop the methods of LAMP and BIOSENSORS for detecting wAlbB Wolbachia in mosquitoes. Our positive LAMP reaction can be visualized by color change from violet to blue at a sensitivity of ≥ 10 pg of genomic DNA. When used in combination with the BIOSENSOR method, the sensitivity increases a millionfold without losing specificity. Our study suggests that both developed methods, either used in combination or stand-alone, are efficient and cost-effective, hence, they could be applied for routine surveys of Wolbachia in mosquito control programs that use Wolbachia-based approaches. [ABSTRACT FROM AUTHOR]

Abstract Background There is an urgent need to protect children against dengue since this age group is particularly sensitive to the disease. Since dengue vectors are active mainly during the day, a potential target for control should be schools where children spend a considerable amount of their day. School uniforms are the cultural norm in most developing countries, worn throughout the day. We hypothesise that insecticide-treated school uniforms will reduce the incidence of dengue infection in school-aged children. Our objective is to determine the impact of impregnated school uniforms on dengue incidence. Methods A randomised controlled trial will be conducted in eastern Thailand in a group of schools with approximately 2,000 students aged 7–18 years. Pre-fabricated school uniforms will be commercially treated to ensure consistent, high-quality insecticide impregnation with permethrin. A double-blind, randomised, crossover trial at the school level will cover two dengue transmission seasons. Discussion Practical issues and plans concerning intervention implementation, evaluation, analysing and interpreting the data, and possible policy implications arising from the trial are discussed. Trial registration clinicaltrial.gov. Registration number: NCT01563640

Abstract Background Appropriate supervision, along with availability of an effective system for monitoring and evaluation, is a crucial requirement to guarantee sufficient coverage and quality of malaria vector control procedures. This study evaluated the efficacy of self-assessment practice as a possible innovative method towards achieving high coverage and excellent quality of larviciding operation in Iran. Methods The research was conducted on the randomly selected rural health centre of Kanmbel Soliman with 10 staff and 30 villages, in three main steps: (i) assessment of effectiveness of larviciding operations in the study areas before intervention through external assessment by a research team; (ii) self-assessment of larviciding operations (intervention) by staff every quarter for three rounds; and, (iii) determining the effectiveness of applying self-assessment of larviciding operations in the study areas. Two toolkits were used for self-assessment and external evaluation. The impact of self-assessment of larviciding operations was measured by two indicators: percentage of missed breeding habitats and cleaned breeding habitats among randomly selected breeding sites. Moreover, the correlation coefficients were measured between self-assessment measures and scores from external evaluation. The correlation coefficient and Mann Whitney test were used to analyse data. Results Following the utilization of self-assessment, the percentage of missed breeding habitats decreased significantly from 14.23% to 1.91% (P Before intervention, the results of self-assessment practice were compatible with external evaluation in 76.3% of 139 reviewed reports of self-assessment. After intervention, the findings of self-assessment and external evaluation were similar in the vast majority of reviewed reports (95%). Conclusion The self-assessment tool seems to be valid and reliable in improving effectiveness of larviciding operations. Furthermore, the result of self-assessment is more compatible with external evaluation results if it would be applied frequently. Therefore, it can be used as an alternative assessment technique in the evaluation of larviciding operations in addition to traditional assessment methods.

Abstract Background The highly pathogenic avian influenza (HPAI) H5N1 virus remains a worldwide threat to human and animal health, while the mechanisms explaining its epizootic emergence and re-emergence in poultry are largely unknown. Data from Thailand, a country that experienced significant epidemics in poultry and has recorded suspicious cases of HPAI on a daily basis since 2004, are used here to study the process of emergence. A spatial approach is employed to describe all HPAI H5N1 virus epizootics from 2004 to 2008 and to characterize the pattern of emergence: multiple independent introductions of the virus followed by moderate local spread vs. very rare emergences followed by strong local spread and rare long range diffusion jumps. Sites where epizootics originate (by foreign introduction, local persistence, or long range jump) were selected from those to which the disease subsequently spreads using a filter based on relative date and position. The spatial distribution of these selected foci was statistically analyzed, and to differentiate environmental factors from long range diffusion, we investigate the relationship of these foci with environmental exposure factors and with rearing characteristics. Results During each wave of epizootics, the temporal occurrence of cases did not show a temporal interruption of more than a week. All foci were globally clustered; i.e., more than 90% of cases had a previous case within a 10 km range and a 21 day period of time, showing a strong local spread. We were able to estimate 60 km as the maximum distance for the local farm to farm dissemination process. The remaining "emergent" cases have occurred randomly over Thailand and did not show specific location, clusters, or trends. We found that these foci are not statistically related to specific environmental conditions or land cover characteristics, and most of them may be interpreted as long range diffusion jumps due to commercial practices. Conclusion We conclude that only a few foci appear to have been at the origin of each HPAI epidemic wave, leading to the practical action that surveillance and control must focus on farm to farm transmission rather than on emergence or wild fauna.

Important arboviral diseases, such as dengue, chikungunya, and Zika virus infections, are transmitted mainly by the Aedes aegypti vector. So far, controlling this vector species with current tools and strategies has not demonstrated sustainable and significant impacts. Our main objective was to evaluate whether open field release of sterile males, produced from combining the sterile insect technique using radiation with the insect incompatible technique through Wolbachia-induced incompatibility (SIT/IIT), could suppress natural populations of Ae. aegypti in semi-rural village settings in Thailand. Irradiated Wolbachia-infected Aedes aegypti males produced by the SIT/IIT approach were completely sterile and were able to compete with the wild fertile ones. Open field release of these sterile males was conducted in an ecologically isolated village in Chachoengsao Province, eastern Thailand. House-to-house visit and media reports resulted in community acceptance and public awareness of the technology. During intervention, approximately 100–200 sterile males were released weekly in each household. After 6 months of sterile male release, a significant reduction (p<0.05) of the mean egg hatch rate (84%) and the mean number of females per household (97.30%) was achieved in the treatment areas when compared to the control ones. Our study represents the first open field release of sterile Ae. aegypti males developed from a combined SIT/IIT approach. Entomological assessment using ovitraps, adult sticky traps, and portable vacuum aspirators confirmed the success in reducing natural populations of Ae. aegypti females in treated areas. Public awareness through media resulted in positive support for practical use of this strategy in wider areas. Further study using a systematic randomized trial is needed to determine whether this approach could have a significant impact on the diseases transmitted by Ae. aegypti vector. Dengue, chikungunya, and Zika are important diseases that pass to humans only by the bites of Aedes aegypti mosquitoes infected with these viruses. Due to the lack of an effective vaccine and drug to cure these diseases, mosquito control is the only method available to reduce disease risk. Most of the available preventive and control measures involve an application of chemical-based products. The inappropriate use of chemicals causes insecticide resistance and environmental contamination. In this study, we report on the pilot trial of an alternative, safe, and environmental friendly approach to suppress Ae. aegypti mosquito populations. This alternative method involves the release of sterile Ae. aegypti males that were infected with, naturally-occurring, insect bacteria Wolbachia, and were irradiated at low doses to obtain full sterilization. The pilot trial involved the release of 100–250 sterile males per household in a treated area over a 6-month period. High efficacy of this approach was evidenced from a significant reduction in the numbers of wild Ae. aegypti females and an increase in sterility by reduction in the egg hatch rate of wild Ae. aegypti females in the treated area. Public awareness through media resulted in public support to conduct trials in wider areas. [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate Photorhabdus insect-related protein (Pir) from Photorhabdus asymbiotica against dengue vectors. PirAB exhibited larvicidal activity against both Aedes aegypti and Aedes albopictus larvae bud did not affect the Mesocyclops thermocyclopoides predator.

Vector-borne diseases are a major health burden, yet factors affecting their spread are only partially understood. For example, microbial symbionts can impact mosquito reproduction, survival, and vectorial capacity, and hence affect disease transmission. Nonetheless, current knowledge of mosquito-associated microbial communities is limited. To characterize the bacterial and eukaryotic microbial communities of multiple vector species collected from different habitat types in disease endemic areas, we employed next-generation 454 pyrosequencing of 16S and 18S rRNA amplicon libraries, also known as metabarcoding. We investigated pooled whole adult mosquitoes of three medically important vectors, Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus, collected from different habitats across central Thailand where we previously characterized mosquito diversity. Our results indicate that diversity within the mosquito microbiota is low, with the majority of microbes assigned to one or a few taxa. Two of the most common eukaryotic and bacterial genera recovered (Ascogregarina and Wolbachia, respectively) are known mosquito endosymbionts with potentially parasitic and long evolutionary relationships with their hosts. Patterns of microbial composition and diversity appeared to differ by both vector species and habitat for a given species, although high variability between samples suggests a strong stochastic element to microbiota assembly. In general, our findings suggest that multiple factors, such as habitat condition and mosquito species identity, may influence overall microbial community composition, and thus provide a basis for further investigations into the interactions between vectors, their microbial communities, and human-impacted landscapes that may ultimately affect vector-borne disease risk. [ABSTRACT FROM AUTHOR]

Background: Dengue-related illness is a leading cause of hospitalization and death in Thailand and other Southeast Asian countries, imposing a major economic burden on households, health systems, and governments. This study aims to assess the economic impact of hospitalized dengue cases on households in Chachoengsao province in eastern Thailand. Methods: We conducted a prospective cost-of-illness study of hospitalized pediatric and adult dengue patients at three public hospitals. We examined all hospitalized dengue cases regardless of disease severity. Patients or their legal guardians were interviewed using a standard questionnaire to determine household-level medical and non-medical expenditures and income losses during the illness episode. Results: Between March and September 2015, we recruited a total of 224 hospitalized patients (<5 years, 4%; 5–14 years, 20%, 15–24 years, 36%, 25–34 years, 15%; 35–44 years, 10%; 45+ years, 12%), who were clinically diagnosed with dengue. The total cost of a hospitalized dengue case was higher for adult patients than pediatric patients, and was US$153.6 and US$166.3 for pediatric DF and DHF patients, respectively, and US$171.2 and US$226.1 for adult DF and DHF patients, respectively. The financial burden on households increased with the severity of dengue illness. Conclusions: Although 74% of the households reported that the patient received free medical care, hospitalized dengue illness cost approximately 19–23% of the monthly household income. These results indicated that dengue imposed a substantial financial burden on households in Thailand where a great majority of the population was covered by the Universal Coverage Scheme for health care. [ABSTRACT FROM AUTHOR]

Background: Dengue is a vector-borne disease transmitted by Aedes mosquitoes. It is considered an important public health problem in many countries worldwide. However, only a few studies have been conducted on primates and domestic animals that could potentially be a reservoir of dengue viruses. Since domestic dogs share both habitats and vectors with humans, this study aimed to investigate whether domestic dogs living in different ecological settings in dengue endemic areas in Thailand could be naturally infected with dengue viruses. Methodology/Principal findings: Serum samples were collected from domestic dogs in three different ecological settings of Thailand: urban dengue endemic areas of Nakhon Sawan Province; rubber plantation areas of Rayong Province; and Koh Chang, an island tourist spot of Trat Province. These samples were screened for dengue viral genome by using semi-nested RT-PCR. Positive samples were then inoculated in mosquito and dog cell lines for virus isolation. Supernatant collected from cell culture was tested for the presence of dengue viral genome by semi-nested RT-PCR, then double-strand DNA products were double-pass custom-sequenced. Partial nucleotide sequences were aligned with the sequences already recorded in GenBank, and a phylogenetic tree was constructed. In the urban setting, 632 domestic dog serum samples were screened for dengue virus genome by RT-PCR, and six samples (0.95%) tested positive for dengue virus. Four out of six dengue viruses from positive samples were successfully isolated. Dengue virus serotype 2 and serotype 3 were found to have circulated in domestic dog populations. One of 153 samples (0.65%) collected from the rubber plantation area showed a PCR-positive result, and dengue serotype 3 was successfully isolated. Partial gene phylogeny revealed that the isolated dengue viruses were closely related to those strains circulating in human populations. None of the 71 samples collected from the island tourist spot showed a positive result. Conclusions/Significance: We concluded that domestic dogs can be infected with dengue virus strains circulating in dengue endemic areas. The role of domestic dogs in dengue transmission needs to be further investigated, i.e., whether they are potential reservoirs or incidental hosts of dengue viruses. [ABSTRACT FROM AUTHOR]

Background: Viral diseases transmitted via Aedes mosquitoes are on the rise, such as Zika, dengue, and chikungunya. Novel tools to mitigate Aedes mosquitoes-transmitted diseases are urgently needed. We tested whether commercially insecticide-impregnated school uniforms can reduce dengue incidence in school children. Methods: We designed a cluster-randomised controlled trial in Thailand. The primary endpoint was laboratory-confirmed dengue infections. Secondary endpoints were school absenteeism; and impregnated uniforms’ 1-hour knock-down and 24 hour mosquito mortality as measured by standardised WHOPES bioassay cone tests at baseline and after repeated washing. Furthermore, entomological assessments inside classrooms and in outside areas of schools were conducted. Results: We enrolled 1,811 pupils aged 6–17 from 5 intervention and 5 control schools. Paired serum samples were obtained from 1,655 pupils. In the control schools, 24/641 (3.7%) and in the intervention schools 33/1,014 (3.3%) students had evidence of new dengue infections during one school term (5 months). There was no significant difference in proportions of students having incident dengue infections between the intervention and control schools, with adjustment for clustering by school. WHOPES cone tests showed a 100% knock down and mortality of Aedes aegypti mosquitoes exposed to impregnated clothing at baseline and up to 4 washes, but this efficacy rapidly declined to below 20% after 20 washes, corresponding to a weekly reduction in knock-down and mosquito mortality by 4.7% and 4.4% respectively. Results of the entomological assessments showed that the mean number of Aedes aegypti mosquitoes caught inside the classrooms of the intervention schools was significantly reduced in the month following the introduction of the impregnated uniforms, compared to those collected in classrooms of the control schools (p = 0.04) Conclusions: Entomological assessments showed that the intervention had some impact on the number of Aedes mosquitoes inside treatment schools immediately after impregnation and before insecticidal activity declined. However, there was no serological evidence of protection against dengue infections over the five months school term, best explained by the rapid washing-out of permethrin after 4 washes. If rapid washing-out of permethrin could be overcome by novel technological approaches, insecticide-treated clothes might become a potentially cost-effective and scalable intervention to protect against diseases transmitted by Aedes mosquitoes such as dengue, Zika, and chikungunya. Trial Registration: ClinicalTrials.gov [ABSTRACT FROM AUTHOR]

Background: Dengue is an important neglected tropical disease, with more than half of the world’s population living in dengue endemic areas. Good understanding of dengue transmission sites is a critical factor to implement effective vector control measures. Methods: A cohort of 1,811 students from 10 schools in rural, semi-rural and semi-urban Thailand participated in this study. Seroconversion data and location of participants’ residences and schools were recorded to determine spatial patterns of dengue infections. Blood samples were taken to confirm dengue infections in participants at the beginning and the end of school term. Entomological factors included a survey of adult mosquito density using a portable vacuum aspirator during the school term and a follow up survey of breeding sites of Aedes vectors in schools after the school term. Clustering analyses were performed to detect spatial aggregation of dengue infections among participants. Results: A total of 57 dengue seroconversions were detected among the 1,655 participants who provided paired blood samples. Of the 57 confirmed dengue infections, 23 (40.0%) occurred in students from 6 (6.8%) of the 88 classrooms in 10 schools. Dengue infections did not show significant clustering by residential location in the study area. During the school term, a total of 66 Aedes aegypti mosquitoes were identified from the 278 mosquitoes caught in 50 classrooms of the 10 schools. In a follow-up survey of breeding sites, 484 out of 2,399 water containers surveyed (20.2%) were identified as active mosquito breeding sites. Discussion and Conclusion: Our findings suggest that dengue infections were clustered among schools and among classrooms within schools. The schools studied were found to contain a large number of different types of breeding sites. Aedes vector densities in schools were correlated with dengue infections and breeding sites in those schools. Given that only a small proportion of breeding sites in the schools were subjected to vector control measures (11%), this study emphasizes the urgent need to implement vector control strategies at schools, while maintaining efforts at the household level. [ABSTRACT FROM AUTHOR]

Background: Dengue-related illness is a leading cause of hospitalization and death, particularly among children. Practical, acceptable and affordable measures are urgently needed to protect this age group. Schools where children spend most of their day is proposed as an ideal setting to implement preventive strategies against day-biting Aedes mosquitoes. The use of insecticide-treated school uniforms is a promising strategy currently under investigation. Methods: Using a decision-analytic model, we evaluated the cost-effectiveness of the use of insecticide-treated school uniforms for prevention of dengue, compared with a “do-nothing” alternative, in schoolchildren from the societal perspective. We explored how the potential economic value of the intervention varied under various scenarios of intervention effectiveness and cost, as well as dengue infection risk in school-aged children, using data specific to Thailand. Results: At an average dengue incidence rate of 5.8% per year in school-aged children, the intervention was cost-effective (ICER≤$16,440) in a variety of scenarios when the intervention cost per child was $5.3 or less and the intervention effectiveness was 50% or higher. In fact, the intervention was cost saving (ICER<0) in all scenarios in which the intervention cost per child was $2.9 or less per year and the intervention effectiveness was 50% or higher. The results suggested that this intervention would be of no interest to Thai policy makers when the intervention cost per child was $10.6 or higher per year regardless of intervention effectiveness (ICER>$16,440). Conclusions: Our results present the potential economic value of the use of insecticide-treated uniforms for prevention of dengue in schoolchildren in a typical dengue endemic setting and highlight the urgent need for additional research on this intervention. [ABSTRACT FROM AUTHOR]

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Background: As current dengue control strategies have been shown to be largely ineffective in reducing dengue in school-aged children, novel approaches towards dengue control need to be studied. Insecticideimpregnated school uniforms represent an innovative approach with the theoretical potential to reduce dengue infections in school children. Objectives: This study took place in the context of a randomised control trial (RCT) to test the effectiveness of permethrin-impregnated school uniforms (ISUs) for dengue prevention in Chachoengsao Province, Thailand. The objective was to assess the acceptability of ISUs among parents, teachers, and principals of school children involved in the trial. Methodology: Quantitative and qualitative tools were used in a mixed methods approach. Class-clustered randomised samples of school children enrolled in the RCT were selected and their parents completed 321 self-administered questionnaires. Descriptive statistics and logistic regression were used to analyse the quantitative data. Focus group discussions and individual semi-structured interviews were conducted with parents, teachers, and principals. Qualitative data analysis involved content analysis with coding and thematic development. Results: The knowledge and experience of dengue was substantial. The acceptability of ISUs was high. Parents (87.3%; 95% CI 82.990.8) would allow their child to wear an ISU and 59.9% (95% CI 53.765.9) of parents would incur additional costs for an ISU over a normal uniform. This was significantly associated with the total monthly income of a household and the educational level of the respondent. Parents (62.5%; 95% CI 56.668.1) indicated they would be willing to recommend ISUs to other parents. Conclusions: Acceptability of the novel tool of ISUs was high as defined by the lack of concern along with the willingness to pay and recommend. Considering issues of effectiveness and scalability, assessing acceptability of ISUs over time is recommended. [ABSTRACT FROM AUTHOR]

Recent years have seen the greatest ecological disturbances of our times, with global human expansion, species and habitat loss, climate change, and the emergence of new and previously-known infectious diseases. Biodiversity loss affects infectious disease risk by disrupting normal relationships between hosts and pathogens. Mosquito-borne pathogens respond to changing dynamics on multiple transmission levels and appear to increase in disturbed systems, yet current knowledge of mosquito diversity and the relative abundance of vectors as a function of habitat change is limited. We characterize mosquito communities across habitats with differing levels of anthropogenic ecological disturbance in central Thailand. During the 2008 rainy season, adult mosquito collections from 24 sites, representing 6 habitat types ranging from forest to urban, yielded 62,126 intact female mosquitoes (83,325 total mosquitoes) that were assigned to 109 taxa. Female mosquito abundance was highest in rice fields and lowest in forests. Diversity indices and rarefied species richness estimates indicate the mosquito fauna was more diverse in rural and less diverse in rice field habitats, while extrapolated estimates of true richness (Chao1 and ACE) indicated higher diversity in the forest and fragmented forest habitats and lower diversity in the urban. Culex sp. (Vishnui subgroup) was the most common taxon found overall and the most frequent in fragmented forest, rice field, rural, and suburban habitats. The distributions of species of medical importance differed significantly across habitat types and were always lowest in the intact, forest habitat. The relative abundance of key vector species, Aedes aegypti and Culex quinquefasciatus, was negatively correlated with diversity, suggesting that direct species interactions and/or habitat-mediated factors differentially affecting invasive disease vectors may be important mechanisms linking biodiversity loss to human health. Our results are an important first step for understanding the dynamics of mosquito vector distributions under changing environmental features across landscapes of Thailand. Author Summary: Biodiversity affects the long-term health of a community by virtue of the many interactions constituent organisms depend upon. Mosquito-borne diseases are particularly likely to respond to changes on multiple transmission levels that span mosquito and vertebrate host communities. We characterized mosquito communities across habitats with differing levels of anthropogenic degradation in central Thailand. During the 2008 rainy season, 83,325 adult mosquitoes were collected from 24 sites, representing 6 habitat types ranging from forest to urban, of which 62,126 females were assigned to 109 taxa. Extrapolated estimates of true richness (Chao1 and ACE) indicated higher diversity of mosquito communities in forest/fragmented forests and lower diversity in urban habitats. Species of medical importance differed significantly across habitats and were always lowest in forest. The relative abundance of vectors Aedes aegypti and Culex quinquefasciatus was negatively correlated with biodiversity, suggesting that direct species interactions and/or habitat-mediated factors differentially affecting invasive vectors may be important mechanisms linking biodiversity loss to human health. Our results represent an important first step towards understanding the distributions of mosquitoes including disease vectors under changing environmental features. [ABSTRACT FROM AUTHOR]

Background: The genetic population structure of Aedes (Stegomyia) aegypti (L.), the main vector of dengue virus, is being investigated in areas where a novel dengue suppression program is to be implemented. The aim of the program is to release and establish mosquito populations with impaired virus transmission capabilities. To model effects of the release and devise protocols for its implementation, information about the genetic structure of populations at a range of spatial scales is required. Methodology/Principal Findings: This study investigates a potential release site in the Hua Sam Rong Subdistrict of Plaeng Yao District, Chachoengsao Province, in eastern Thailand which comprises a complex of five villages within a 10 km radius. Aedes aegypti resting indoors was sampled at four different times of year from houses within the five villages. Genetic markers were used to screen the mosquitoes: two Exon Primed Intron Crossing (EPIC) markers and five microsatellite markers. The raw allele size was determined using several statistical software packages to analyze the population structure of the mosquito. Estimates of effective population size for each village were low, but there was no evidence of genetic isolation by geographic distance. Conclusions: The presence of temporary genetic structure is possibly caused by genetic drift due to large contributions of adults from a few breeding containers. This suggests that the introduction of mosquitoes into an area needs to proceed through multiple releases and targeting of sites where mosquitoes are emerging in large numbers. Author Summary: Knowledge about population structure of Aedes (Stegomyia) aegypti (L.), the main vector of dengue virus, is vital in designing dengue suppression programs. To design a release of dengue resistant mosquitoes, we require information about population structure at a range of spatial scales. This study looked at a small-scale complex of five villages at four sampling periods and mosquitoes from individual houses within the five villages. Genetic markers were used to screen the field-collected mosquitoes in order to characterize population genetic structure. Our results indicated that the effective population size of Ae. aegypti in each village was low. Genetic structure was apparent at local spatial scales, but there was no evidence of genetic isolation by geographic distance. The temporary genetic structure observed may be caused by related individuals emerging from a few productive containers in each village. Our findings could be applied in an effective dengue suppression program by planning multiple releases of dengue resistant mosquitoes in targeted households of each village where large numbers of adult mosquitoes have emerged from identified productive breeding containers instead of making a release in one area and expecting rapid spread throughout the complex. [ABSTRACT FROM AUTHOR]

Background: Children carry the main burden of morbidity and mortality caused by dengue. Children spend a considerable amount of their day at school; hence strategies that reduce human-mosquito contact to protect against the day-biting habits of Aedes mosquitoes at schools, such as insecticide-impregnated uniforms, could be an effective prevention strategy. Methodology: We used mathematical models to calculate the risk of dengue infection based on force of infection taking into account the estimated proportion of mosquito bites that occur in school and the proportion of school time that children wear the impregnated uniforms. Principal findings: The use of insecticide-impregnated uniforms has efficacy varying from around 6% in the most pessimistic estimations, to 55% in the most optimistic scenarios simulated. Conclusions: Reducing contact between mosquito bites and human hosts via insecticide-treated uniforms during school time is theoretically effective in reducing dengue incidence and may be a valuable additional tool for dengue control in school-aged children. The efficacy of this strategy, however, is dependent on the compliance of the target population in terms of proper and consistent wearing of uniforms and, perhaps more importantly, the proportion of bites inflicted by the Aedes population during school time. [ABSTRACT FROM AUTHOR]

This study analyzed the association between household-level ecologic and individual-level sociodemographic determinants and dengue transmission in urban areas of Chachoengsao province, Thailand. The ecologic and sociodemographic variables were examined by univariate analysis and multivariate logistic regression. In the ecologic model, dengue risk was related to households situated in the ecotope of residential mixed with commercial and densely populated urban residential areas (RCDENPURA) (aOR = 2.23, P = 0.009), high historical dengue risk area (aOR = 2.06, P < 0.001), and presence of household window screens (aOR = 1.62, P = 0.023). In the sociodemographic model, the dengue risk was related to householders aged >45 years (aOR = 3.24, P = 0.003), secondary and higher educational degrees (aOR = 2.33, P = 0.013), household members >4 persons (aOR= 2.01, P = 0.02), and community effort in environmental management by clean-up campaign (aOR = 1.91, P = 0.035). It is possible that the preventive measures were positively correlated with dengue risk because these activities were generally carried out in particular households or communities following dengue experiences or dengue outbreaks. Interestingly, the ecotope of RCDENPURA and high historical dengue risk area appeared to be very good predictors of dengue incidences. [ABSTRACT FROM AUTHOR]

Dengue fever is a mosquito-borne viral disease estimated to cause about 230 million infections worldwide every year, of which 25,000 are fatal. Global incidence has risen rapidly in recent decades with some 3.6 billion people, over half of the world's population, now at risk, mainly in urban centres of the tropics and subtropics. Demographic and societal changes, in particular urbanization, globalization, and increased international travel, are major contributors to the rise in incidence and geographic expansion of dengue infections. Major research gaps continue to hamper the control of dengue. The European Commission launched a call under the 7th Framework Programme with the title of 'Comprehensive control of Dengue fever under changing climatic conditions'. Fourteen partners from several countries in Europe, Asia, and South America formed a consortium named 'DengueTools' to respond to the call to achieve better diagnosis, surveillance, prevention, and predictive models and improve our understanding of the spread of dengue to previously uninfected regions (including Europe) in the context of globalization and climate change. The consortium comprises 12 work packages to address a set of research questions in three areas: Research area 1: Develop a comprehensive early warning and surveillance system that has predictive capability or epidemic dengue and benefits from novel tools for laboratory diagnosis and vector monitoring. Research area 2: Develop novel strategies to prevent dengue in children. Research area 3: Understand and predict the risk of global spread of dengue, in particular the risk of introduction and establishment in Europe, within the context of parameters of vectorial capacity, global mobility, and climate change. In this paper, we report on the rationale and specific study objectives of 'DengueTools'. DengueTools is funded under the Health theme of the Seventh Framework Programme of the European Community, Grant Agreement Number: 282589 Dengue Tools. [ABSTRACT FROM AUTHOR]

Background: The highly pathogenic avian influenza (HPAI) H5N1 virus remains a worldwide threat to human and animal health, while the mechanisms explaining its epizootic emergence and re-emergence in poultry are largely unknown. Data from Thailand, a country that experienced significant epidemics in poultry and has recorded suspicious cases of HPAI on a daily basis since 2004, are used here to study the process of emergence. A spatial approach is employed to describe all HPAI H5N1 virus epizootics from 2004 to 2008 and to characterize the pattern of emergence: multiple independent introductions of the virus followed by moderate local spread vs. very rare emergences followed by strong local spread and rare long range diffusion jumps. Sites where epizootics originate (by foreign introduction, local persistence, or long range jump) were selected from those to which the disease subsequently spreads using a filter based on relative date and position. The spatial distribution of these selected foci was statistically analyzed, and to differentiate environmental factors from long range diffusion, we investigate the relationship of these foci with environmental exposure factors and with rearing characteristics. Results: During each wave of epizootics, the temporal occurrence of cases did not show a temporal interruption of more than a week. All foci were globally clustered; i.e., more than 90% of cases had a previous case within a 10 km range and a 21 day period of time, showing a strong local spread. We were able to estimate 60 km as the maximum distance for the local farm to farm dissemination process. The remaining "emergent" cases have occurred randomly over Thailand and did not show specific location, clusters, or trends. We found that these foci are not statistically related to specific environmental conditions or land cover characteristics, and most of them may be interpreted as long range diffusion jumps due to commercial practices. Conclusion: We conclude that only a few foci appear to have been at the origin of each HPAI epidemic wave, leading to the practical action that surveillance and control must focus on farm to farm transmission rather than on emergence or wild fauna. [ABSTRACT FROM AUTHOR]

Abstract: Species of the genus Wolbachia are a group of Rickettsia-like, maternally-inherited bacteria (gram negative), which cause various reproductive alterations in their arthropod and nematode hosts including cytoplasmic incompatibility (CI), male-killing, parthenogenesis and feminization. They can be divided into supergroups such as A and B based on phylogenetic analysis of 16S rDNA sequences. In this study, we examined the relative infection densities of Wolbachia strains among life cycle stages in the mosquito, Aedes albopictus in terms of crowding effect and temperature effect. A. albopictus is known to be superinfected with both A- and B-supergroup Wolbachia which cause CI. The relative Wolbachia densities within each individual mosquito were determined and quantified by using real-time quantitative PCR assay based on the wsp gene. We found that B-supergroup Wolbachia strain densities in this host species were consistently and significantly higher than in the A-supergroup. Larval crowding also reduced adult size of mosquitoes. Our results show clearly that the higher densities of mosquito larvae cause lower densities of Wolbachia strains. Examination of the effect of temperature on Wolbachia density in each stage of the mosquito clearly revealed a significant decrease in bacterial density following exposure to elevated temperature (37°C) in both males and females. [Copyright &y& Elsevier]

Female Aedes albopictus mosquitoes from natural populations of different geographical regions of Thailand were collected and allowed to oviposit to determine relative Wolbachia A and Wolbachia b densities of their offspring (F1) by using real-time quantitative Pcr (rTQ-Pcr). An important aspect of this work is that all Aedes albopictus mosquitoes were collected from the field. Twenty-seven offspring were from diverse areas of Thailand (songkhla, Konkaen, chantaburi, and Kanchanaburi). The range of relative Wolbabhia A density in F1 mosquitoes was from 0.007 to 1250.78 (bacteria-to-host ratio), whereas relative Wolbachia b densities ranged from 0 to 348.2 (bacteria-to-host ratio). These data are in contrast to those from a previous study that showed a very low amount (less than 0.10) of both relative Wolbachia density types for laboratory strains. The percent transmission of Wolbachia density from mother to each individual offspring cannot be predicted and was not related to the sex of the F1. Obtaining confirmation for variations and unpredictable Wolbachia transmission load raises some concerns about using Wolbachia as a gene-driving system in nature for population replacement if Wolbachia density is involved in cytoplasmic incompatibility in this mosquito. [ABSTRACT FROM AUTHOR]

Wolbachia are a group of intracellular inherited bacteria that infect a wide range of arthropods. They are related with a variety of reproductive alterations in their host, the best known being cytoplasmic incompatibility (CI). In this study, prophage WO gp1, including Wolbachia A and Wolbachia B densities were determined during mosquito development by using real-time quantitative PCR (RTQ-PCR). An interesting result was found for the same flux of prophage WO gp1 and Wolbachia B densities in larva, pupa, 3-day-old adult, and 21-day-old adult of Aedes albopictus mosquito ( Wolbachia superinfection). The results determined that Wolbachia B and prophage WO gp1, developed with the same fluctuation from larval stage through adult stage. However, the same tendency was not observed with Wolbachia A and phageWO gp1. Hence, this bacteriophage gene is more closely associated with Wolbachia B strain than in Wolbachia A in their relative density variations. Assesment of the density data reported herein is the first to suggest the possible association of prophage WO gp1 in CI mechanisms in consequence of the same fluctuation during development with Wolbachia B gene density in Aedes albopictus mosquito. [ABSTRACT FROM AUTHOR]

Dynamics of dengue serotype 2 virus isolated from patients with different disease severity, namely flu-like classic dengue fever (DF) and dengue shock syndrome (DSS) were studied in its mosquito vector Aedes aegypti. We compared isolate infectivity and vector competence (VC) among thirty two A. aegypti-viral isolate pairs. Mosquito populations from high dengue incidence area exhibited overall greater VC than those from low dengue incidence area at 58.1% and 52.5%, respectively. On the other hand, the overall infection rates for the isolates ThNR2/772 (DF, 62.3%) and ThNR2/391 (DSS, 60.9%), were significantly higher than those for isolates ThNR2/406 (DF, 55.2%) and ThNR2/479 (DSS, 54.8%). These results suggest that the efficacy of dengue virus circulation was likely to vary according to the combination between the virus strains and origin of the mosquito strains, and this may have epidemiologic implications toward the incidence of flu-like classic dengue fever (DF) and dengue shock syndrome (DSS). [ABSTRACT FROM AUTHOR]

Background: Dengue fever persists as a major global disease burden, and may increase as a consequence of climate change. Along with other measures, research actions to improve diagnosis, surveillance, prevention, and predictive models are highly relevant. The European Commission funded the DengueTools consortium to lead a major initiative in these areas, and this review synthesises the outputs and findings of this work conducted from 2011 to 2016. Research areas: DengueTools organised its work into three research areas, namely [1] Early warning and surveillance systems; [2] Strategies to prevent dengue in children; and [3] Predictive models for the global spread of dengue. Research area 1 focused on case-studies undertaken in Sri Lanka, including developing laboratory-based sentinel surveillance, evaluating economic impact, identifying drivers of transmission intensity, evaluating outbreak prediction capacity and developing diagnostic capacity. Research area 2 addressed preventing dengue transmission in school children, with case-studies undertaken in Thailand. Insecticide-treated school uniforms represented an intriguing potential approach, with some encouraging results, but which were overshadowed by a lack of persistence of insecticide on the uniforms with repeated washing. Research area 3 evaluated potential global spread of dengue, particularly into dengue-naïve areas such as Europe. The role of international travel, changing boundaries of vectors, developing models of vectorial capacity under different climate change scenarios and strategies for vector control in outbreaks was all evaluated. Concluding remarks: DengueTools was able to make significant advances in methods for understanding and controlling dengue transmission in a range of settings. These will have implications for public health agendas to counteract dengue, including vaccination programmes. Outlook: Towards the end of the DengueTools project, Zika virus emerged as an unexpected epidemic in the central and southern America. Given the similarities between the dengue and Zika viruses, with vectors in common, some of the DengueTools thinking translated readily into the Zika situation. [ABSTRACT FROM AUTHOR]