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mosquito-borne - Top 30 Publications

Peridomestic Aedes malayensis and Aedes albopictus are capable vectors of arboviruses in cities.

Dengue and chikungunya are global re-emerging mosquito-borne diseases. In Singapore, sustained vector control coupled with household improvements reduced domestic mosquito populations for the past 45 years, particularly the primary vector Aedes aegypti. However, while disease incidence was low for the first 30 years following vector control implementation, outbreaks have re-emerged in the past 15 years. Epidemiological observations point to the importance of peridomestic infection in areas not targeted by control programs. We investigated the role of vectors in peri-domestic areas.

Data from salivary gland proteome analysis of female Aedes aegypti Linn.

Salivary gland proteins from female Aedes aegypti mosquito were extracted and analyzed on high-resolution mass spectrometry. Proteomic data was analysed using two search algorithms SEQUEST and Mascot, which results in acquisition of 83,836 spectra which were assigned to 5417 peptides belonging to 1208 proteins.These proteins were then assigned molecular functions and further analysis revealed biological processes they are involved in using Gene Ontology annotations. Several immunity related pathways were found to be enriched in salivary gland.The data of this study are also related to the research article "Mosquito-Borne Diseases and Omics: Salivary gland proteome of the female Aedes aegypti mosquito" (Dhawan et al., 2017) [1]. These data are deposited in ProteomeXchange in the public dataset PXD002468. In addition,a scientific interpretation of this dataset by Dhawan et al. [1] is available at http://dx.doi.org/10.1089/journal.omi.2016.0160.

Suppression of chikungunya virus replication and differential innate responses of human peripheral blood mononuclear cells during co-infection with dengue virus.

Dengue and chikungunya are viral diseases transmitted to humans by infected Aedes spp. mosquitoes. With an estimated 390 million infected people per year dengue virus (DENV) currently causes the most prevalent arboviral disease. During the last decade chikungunya virus (CHIKV) has caused large outbreaks and has expanded its territory causing millions of cases in Asia, Africa and America. The viruses share a common mosquito vector and during the acute phase cause similar flu-like symptoms that can proceed to more severe or debilitating symptoms. The growing overlap in the geographical distribution of these mosquito-borne infections has led to an upsurge in reported cases of DENV/CHIKV co-infections. Unfortunately, at present we have little understanding of consequences of the co-infections to the human host. The overall aim of this study was to define viral replication dynamics and the innate immune signature involved in concurrent DENV and CHIKV infections in human peripheral blood mononuclear cells (PBMCs). We demonstrate that concomitant infection resulted in a significant reduction of CHIKV progeny and moderate enhancement of DENV production. Remarkably, the inhibitory effect of DENV on CHIKV infection occurred independently of DENV replication. Furthermore, changes in type I IFN, IL-6, IL-8, TNF-α, MCP-1 and IP-10 production were observed during concomitant infections. Notably, co-infections led to a significant increase in the levels of TNF-α and IL-6, cytokines that are widely considered to play a crucial role in the early pathogenesis of both viral diseases. In conclusion, our study reveals the interplay of DENV/CHIKV during concomitant infection and provides a framework to investigate viral interaction during co-infections.

Garlic Organosulfur Compounds Reduce Inflammation and Oxidative Stress during Dengue Virus Infection.

Dengue virus (DENV) is a mosquito-borne flavivirus that causes significant global human disease and mortality. One approach to develop treatments for DENV infection and the prevention of severe disease is through investigation of natural medicines. Inflammation plays both beneficial and harmful roles during DENV infection. Studies have proposed that the oxidative stress response may be one mechanism responsible for triggering inflammation during DENV infection. Thus, blocking the oxidative stress response could reduce inflammation and the development of severe disease. Garlic has been shown to both reduce inflammation and affect the oxidative stress response. Here, we show that the garlic active compounds diallyl disulfide (DADS), diallyl sulfide (DAS) and alliin reduced inflammation during DENV infection and show that this reduction is due to the effects on the oxidative stress response. These results suggest that garlic could be used as an alternative treatment for DENV infection and for the prevention of severe disease development.

The interplay of climate, intervention and imported cases as determinants of the 2014 dengue outbreak in Guangzhou.

Dengue is a fast spreading mosquito-borne disease that affects more than half of the population worldwide. An unprecedented outbreak happened in Guangzhou, China in 2014, which contributed 52 percent of all dengue cases that occurred in mainland China between 1990 and 2015. Our previous analysis, based on a deterministic model, concluded that the early timing of the first imported case that triggered local transmission and the excessive rainfall thereafter were the most important determinants of the large final epidemic size in 2014. However, the deterministic model did not allow us to explore the driving force of the early local transmission. Here, we expand the model to include stochastic elements and calculate the successful invasion rate of cases that entered Guangzhou at different times under different climate and intervention scenarios. The conclusion is that the higher number of imported cases in May and June was responsible for the early outbreak instead of climate. Although the excessive rainfall in 2014 did increase the success rate, this effect was offset by the low initial water level caused by interventions in late 2013. The success rate is strongly dependent on mosquito abundance during the recovery period of the imported case, since the first step of a successful invasion is infecting at least one local mosquito. The average final epidemic size of successful invasion decreases exponentially with introduction time, which means if an imported case in early summer initiates the infection process, the final number infected can be extremely large. Therefore, dengue outbreaks occurring in Thailand, Singapore, Malaysia and Vietnam in early summer merit greater attention, since the travel volumes between Guangzhou and these countries are large. As the climate changes, destroying mosquito breeding sites in Guangzhou can mitigate the detrimental effects of the probable increase in rainfall in spring and summer.

Garlic Organosulfur Compounds Reduce Inflammation and Oxidative Stress during Dengue Virus Infection.

Dengue virus (DENV) is a mosquito-borne flavivirus that causes significant global human disease and mortality. One approach to develop treatments for DENV infection and the prevention of severe disease is through investigation of natural medicines. Inflammation plays both beneficial and harmful roles during DENV infection. Studies have proposed that the oxidative stress response may be one mechanism responsible for triggering inflammation during DENV infection. Thus, blocking the oxidative stress response could reduce inflammation and the development of severe disease. Garlic has been shown to both reduce inflammation and affect the oxidative stress response. Here, we show that the garlic active compounds diallyl disulfide (DADS), diallyl sulfide (DAS) and alliin reduced inflammation during DENV infection and show that this reduction is due to the effects on the oxidative stress response. These results suggest that garlic could be used as an alternative treatment for DENV infection and for the prevention of severe disease development.

Global Alert: Zika Virus-an Emerging Arbovirus.

Zika virus (ZIKV) is an arbovirus of the Flavivirus genus, and it has an envelope and a single RNA molecule. In early 2016, the World Health Organization declared ZIKV infection to be an emerging global health threat. The major transmission route of the virus to humans is Aedes mosquitoes. ZIKV can be transmitted between humans by transplacental, perinatal, and sexual routes and via blood and body fluids. ZIKV infection usually results in a mild and self-limiting disease with low-grade fever, conjunctivitis, and periorbital edema. Neurological complications such as Guillain-Barré syndrome, meningoencephalitis, acute disseminated encephalomyelitis, acute myelitis, and transverse myelitis have been reported during ZIKV infection. Intrauterine and congenital ZIKV infections have strong teratogenic effects on the fetus. Intrauterine or congenital ZIKV infection can lead to microcephaly, ocular anomalies (such as macular atrophy, pigment mottling, and optic nerve anomalies), and cardiac anomalies (such as atrial or ventricular septal defect). Calcification in the brain between the cortical and subcortical areas, ventriculomegaly, cerebellar hypoplasia, corpus callosum hypoplasia, cortical/subcortical atrophy, delayed myelination, enlarged cisterna magna, and craniofacial disproportion have been reported as brain development defects. ZIKV infection usually results in a mild disease, and it does not require specific therapy. However, complications of infection during the early period of life are serious. Thus, many drugs have been investigated, and vaccine development studies have been conducted to prevent ZIKV infection. Vector control and personal protection from mosquito-borne transmission are important for decreasing the prevalence of ZIKV infection. In particular, pregnant residents or travelers to endemic areas should be carefully protected against mosquito-borne transmission.

Zika Virus in Ontario: Evaluating a Rapid Risk Assessment Tool for Emerging Infectious Disease Threats.

To determine the Ontario-specific risk of local and travel-related Zika virus transmission in the context of a public health emergency of international concern, Public Health Ontario (PHO) completed a rapid risk assessment (RRA) on January 29, 2016, using a newly developed RRA guidance tool. The RRA concluded that risk of local mosquito-borne transmission was low, with a high risk of imported cases through travel. The RRA was updated 3 times based on predetermined triggers. An independent evaluation assessed both the application of the RRA guidance tool (process evaluation) and the usefulness of the RRA (outcome evaluation). We conducted face-to-face, semi-structured interviews with 7 individuals who participated in the creation or review of the Zika virus RRA and 4 end-users at PHO and the Ministry of Health and Long-Term Care. An inductive thematic analysis of responses was undertaken, whereby themes were directly informed by the data. The process evaluation determined that most steps outlined in the RRA guidance tool were adhered to, including forming a cross-functional writing team, clarifying the scope and describing context, completing the RRA summary report, and updating the RRA based on predefined triggers. The outcome evaluation found that end-users judged the Zika virus RRA as evidence-informed, useful, consistent, and timely. The evaluation established that the locally tailored guidance tool, adapted from national and international approaches to RRAs, facilitated a systematic, evidence-informed, and timely formal RRA process at PHO for the Zika virus RRA, which met the needs of end-users. Based on the evaluation, PHO will modify future RRAs by incorporating some flexibility into the literature review process to support timeliness of the RRA, explicitly describing the limitations of studies used to inform the RRA, and refining risk algorithms to better suit emerging infectious disease threats. It is anticipated that these refinements will improve upon the timely assessment of novel or reemerging infectious diseases.

Advances in dengue virus research in Colombia: the role of cellular microRNAs as an anti-dengue virus response.

Dengue is one of the most important mosquito-borne diseases, and its incidence has increased at an alarming rate in recent years, becoming a real public health problem. Currently, there is no vaccine or medication or proper treatment for dengue control. Considering this situation, it is necessary to prioritize the search for new alternatives and strategies for dengue prevention and control, in order to reduce not only the economic burden of endemic countries, but also to improve the quality of life of patients. In this regard, a brief reflection on some aspects related to the search for new alternatives in Colombia is presented. This is focused on the use of microRNAs, which could be a new strategy with great therapeutic potential.

Modelling the effects of global climate change on Chikungunya transmission in the 21(st) century.

The arrival and rapid spread of the mosquito-borne viral disease Chikungunya across the Americas is one of the most significant public health developments of recent years, preceding and mirroring the subsequent spread of Zika. Globalization in trade and travel can lead to the importation of these viruses, but climatic conditions strongly affect the efficiency of transmission in local settings. In order to direct preparedness for future outbreaks, it is necessary to anticipate global regions that could become suitable for Chikungunya transmission. Here, we present global correlative niche models for autochthonous Chikungunya transmission. These models were used as the basis for projections under the representative concentration pathway (RCP) 4.5 and 8.5 climate change scenarios. In a further step, hazard maps, which account for population densities, were produced. The baseline models successfully delineate current areas of active Chikungunya transmission. Projections under the RCP 4.5 and 8.5 scenarios suggest the likelihood of expansion of transmission-suitable areas in many parts of the world, including China, sub-Saharan Africa, South America, the United States and continental Europe. The models presented here can be used to inform public health preparedness planning in a highly interconnected world.

A Novel Cause of Chronic Viral Meningoencephalitis: Cache Valley Virus.

Immunodeficient patients are particularly vulnerable to neuroinvasive infections that can be challenging to diagnose. Metagenomic next-generation sequencing can identify unusual or novel microbes and is therefore well suited for investigating the etiology of chronic meningoencephalitis in immunodeficient patients.

Therapeutic administration of a recombinant human monoclonal antibody reduces the severity of chikungunya virus disease in rhesus macaques.

Chikungunya virus (CHIKV) is a mosquito-borne virus that causes a febrile syndrome in humans associated with acute and chronic debilitating joint and muscle pain. Currently no licensed vaccines or therapeutics are available to prevent or treat CHIKV infections. We recently isolated a panel of potently neutralizing human monoclonal antibodies (mAbs), one (4N12) of which exhibited prophylactic and post-exposure therapeutic activity against CHIKV in immunocompromised mice. Here, we describe the development of an engineered CHIKV mAb, designated SVIR001, that has similar antigen binding and neutralization profiles to its parent, 4N12. Because therapeutic administration of SVIR001 in immunocompetent mice significantly reduced viral load in joint tissues, we evaluated its efficacy in a rhesus macaque model of CHIKV infection. Rhesus macaques that were treated after infection with SVIR001 showed rapid elimination of viremia and less severe joint infiltration and disease compared to animals treated with SVIR002, an isotype control mAb. SVIR001 reduced viral burden at the site of infection and at distant sites and also diminished the numbers of activated innate immune cells and levels of pro-inflammatory cytokines and chemokines. SVIR001 therapy; however, did not substantively reduce the induction of CHIKV-specific B or T cell responses. Collectively, these results show promising therapeutic activity of a human anti-CHIKV mAb in rhesus macaques and provide proof-of-principle for its possible use in humans to treat active CHIKV infections.

Is Usutu virus ready for prime time?

Although considered a neglected tropical disease, the mosquito-borne Usutu virus has demonstrated signs of emergence from Africa to Europe. While human cases are infrequent, the potential for neuroinvasive infection, even in immunocompetent individuals, suggests a need for increased research into virus biology and pathogenesis, as well as rapid measures for diagnosis and environmental surveillance.

Co-occurrence of viruses and mosquitoes at the vectors' optimal climate range: An underestimated risk to temperate regions?

Mosquito-borne viruses have been estimated to cause over 100 million cases of human disease annually. Many methodologies have been developed to help identify areas most at risk from transmission of these viruses. However, generally, these methodologies focus predominantly on the effects of climate on either the vectors or the pathogens they spread, and do not consider the dynamic interaction between the optimal conditions for both vector and virus. Here, we use a new approach that considers the complex interplay between the optimal temperature for virus transmission, and the optimal climate for the mosquito vectors. Using published geolocated data we identified temperature and rainfall ranges in which a number of mosquito vectors have been observed to co-occur with West Nile virus, dengue virus or chikungunya virus. We then investigated whether the optimal climate for co-occurrence of vector and virus varies between "warmer" and "cooler" adapted vectors for the same virus. We found that different mosquito vectors co-occur with the same virus at different temperatures, despite significant overlap in vector temperature ranges. Specifically, we found that co-occurrence correlates with the optimal climatic conditions for the respective vector; cooler-adapted mosquitoes tend to co-occur with the same virus in cooler conditions than their warmer-adapted counterparts. We conclude that mosquitoes appear to be most able to transmit virus in the mosquitoes' optimal climate range, and hypothesise that this may be due to proportionally over-extended vector longevity, and other increased fitness attributes, within this optimal range. These results suggest that the threat posed by vector-competent mosquito species indigenous to temperate regions may have been underestimated, whilst the threat arising from invasive tropical vectors moving to cooler temperate regions may be overestimated.

Pregnancy Outcomes After Maternal Zika Virus Infection During Pregnancy - U.S. Territories, January 1, 2016-April 25, 2017.

Pregnant women living in or traveling to areas with local mosquito-borne Zika virus transmission are at risk for Zika virus infection, which can lead to severe fetal and infant brain abnormalities and microcephaly (1). In February 2016, CDC recommended 1) routine testing for Zika virus infection of asymptomatic pregnant women living in areas with ongoing local Zika virus transmission at the first prenatal care visit, 2) retesting during the second trimester for women who initially test negative, and 3) testing of pregnant women with signs or symptoms consistent with Zika virus disease (e.g., fever, rash, arthralgia, or conjunctivitis) at any time during pregnancy (2). To collect information about pregnant women with laboratory evidence of recent possible Zika virus infection* and outcomes in their fetuses and infants, CDC established pregnancy and infant registries (3). During January 1, 2016-April 25, 2017, U.S. territories(†) with local transmission of Zika virus reported 2,549 completed pregnancies(§) (live births and pregnancy losses at any gestational age) with laboratory evidence of recent possible Zika virus infection; 5% of fetuses or infants resulting from these pregnancies had birth defects potentially associated with Zika virus infection(¶) (4,5). Among completed pregnancies with positive nucleic acid tests confirming Zika infection identified in the first, second, and third trimesters, the percentage of fetuses or infants with possible Zika-associated birth defects was 8%, 5%, and 4%, respectively. Among liveborn infants, 59% had Zika laboratory testing results reported to the pregnancy and infant registries. Identification and follow-up of infants born to women with laboratory evidence of recent possible Zika virus infection during pregnancy permits timely and appropriate clinical intervention services (6).

A Comparative Study of the Trends of Imported Dengue Cases in Korea and Japan 2011 - 2015.

Dengue is a mosquito-borne febrile disease that represents a major public health problem in tropical and subtropical areas. Even though Korea and Japan are not the regions where dengue is epidemic, there have been many imported cases in both countries, and in increasing numbers. A better understanding of the characteristics of the prevalence of dengue and the recent trends in these neighboring countries may provide information to promote improvement and control strategies for both. The present study investigated the epidemiological status of imported dengue cases in Korea and Japan between 2011 and 2015, and compared their characteristics.

Interventions for treating patients with chikungunya virus infection-related rheumatic and musculoskeletal disorders: A systematic review.

Chikungunya virus infection (CHIKV) is caused by a mosquito-borne alphavirus. CHIKV causes high fever and painful rheumatic disorders that may persist for years. Because little is known about interventions for treating CHIKV-related illness, we conducted a systematic review.

Analysis of population structure and insecticide resistance in mosquitoes of the genus Culex, Anopheles and Aedes from different environments of Greece with a history of mosquito borne disease transmission.

Greece has been recently affected by several mosquito borne diseases with the West Nile Virus (WNV) outbreak in 2010 being one of the largest reported in Europe. Currently at the epicenter of an economic and refugee crisis and visited by over 16 million tourists a year the integrated management of diseases transmitted by mosquitoes is a public health and economic priority. Vector control programs rely mainly on insecticides, however data on insecticide resistance and the mosquito fauna is essential for successful applications. We determined the mosquito species composition and population dynamics in areas of increased vulnerability to vector borne disease transmission, as well as investigated the resistance status of major nuisance and disease vectors to insecticides. High mosquito densities were recorded in Thessaloniki and Evros, with Aedes caspius, a nuisance species, Culex pipiens, a known vector of WNV and Anopheles hyrcanus a potential vector of malaria being among the most prevalent species. Both vector species populations reached their peak in late summer. Aedes albopictus was recorded at high densities in Thessaloniki, but not in Evros. Notably, Cx. pipiens hybrids, which show an opportunistic biting behavior and are suspected to be involved in the transmission of the WNV, were recorded in considerable numbers in Thessaloniki and Attica. Culex pipiens and An. hyrcanus, but not Ae. caspius mosquitoes, showed moderate levels of resistance to deltamethrin. The presence of resistance in areas not exposed to vector control indicates that other factors could be selecting for resistance, i.e. pesticide applications for agriculture. Both L1014F and L101C kdr mutations were detected in Cx. pipiens populations. Anopheles hyrcanus resistance was not associated with mutations at the L1014 site. The Ace-1 mutations conferring insensitivity to organophosphates and carbamates were detected at low frequencies in all Cx. pipiens populations. Increased activity of P450s and esterases was found in Cx. pipiens individuals from Thessaloniki. Our study contributes evidence for sustainable and efficient vector control strategies and the prevention of disease outbreaks.

Detection, phenotyping and quantification of dengue virus-specific B cells using fluorescent probes.

Dengue viruses are some of the most important mosquito-borne pathogens worldwide. They cause illness in 50-100 million individuals per year and have a significant global health impact in low- and middle-income countries. It is important to improve our understanding of the humoral response to dengue virus, as antibodies (Abs) are associated with protection from or susceptibility to severe dengue disease. In recent years, significant advances have been made toward identifying Ab targets and evaluating the functional properties of Abs. However, much less is known about the cellular source of Abs, B cells, in part because the reagents to phenotype and characterize antigen-specific B cells have been challenging to develop. Here, we discuss our recent experience with developing and using fluorescent viruses to probe the B cell response to dengue virus. We present the strengths and weaknesses of flow cytometric analysis of antigen-specific B cells and discuss the use of these probes to phenotype and characterize specific B cells during and after natural infection and in ongoing dengue vaccine trials.

An overview of Usutu virus.

Usutu virus (USUV) is a mosquito-borne flavivirus that emerged in Africa in the middle of the 16th century and currently widely circulates in several European countries. Herein, we summarize current knowledge about USUV from ecology, epidemiology, phylogeny to clinical manifestations and diagnosis and discuss the role as human pathogen.

Chemical signaling in mosquito-host interactions: the role of human skin microbiota.

Anthropophilic mosquitoes use host-derived volatile compounds for host seeking. Recently it has become evident that many of these compounds are of microbial origin. Host seeking of mosquitoes is, therefore, a tritrophic relationship and suggests co-evolution between blood hosts and their microbial community to the benefit of the mosquito. Chemical analysis of bacterial headspace resulted in discovery of several compounds that make up the attractive blend to which mosquitoes respond. Future studies should determine which host factors shape the skin microbial community and attractive volatiles produced. It is argued that skin microbial volatiles can be exploited for the control of mosquitoes and hence as a tool for mosquito-borne disease control and thus aid in the elimination of vector-borne disease.

Ecological Niche Modeling Identifies Fine-Scale Areas at High Risk of Dengue Fever in the Pearl River Delta, China.

Dengue fever (DF) is one of the most common and rapidly spreading mosquito-borne viral diseases in tropical and subtropical regions. In recent years, this imported disease has posed a serious threat to public health in China, especially in the Pearl River Delta (PRD). Although the severity of DF outbreaks in the PRD is generally associated with known risk factors, fine scale assessments of areas at high risk for DF outbreaks are limited. We built five ecological niche models to identify such areas including a variety of climatic, environmental, and socioeconomic variables, as well as, in some models, extracted principal components. All the models we tested accurately identified the risk of DF, the area under the receiver operating characteristic curve (AUC) were greater than 0.8, but the model using all original variables was the most accurate (AUC = 0.906). Socioeconomic variables had a greater impact on this model (total contribution 55.27%) than climatic and environmental variables (total contribution 44.93%). We found the highest risk of DF outbreaks on the border of Guangzhou and Foshan (in the central PRD), and in northern Zhongshan (in the southern PRD). Our fine-scale results may help health agencies to focus epidemic monitoring tightly on the areas at highest risk of DF outbreaks.

Awareness and Outcome of Changing Trends in Clinical Profile of Dengue Fever: A Retrospective Analysis of Dengue Epidemic from January to December 2014 at a Tertiary Care Hospital.

Dengue fever is caused by mosquito-borne arboviral infection that has become a public health concern globally. Recently, an alarming rise of dengue has also been seen in India. Hence the study was undertaken to know profile of clinical manifestations and laboratory findings during the evolution of dengue fever.

Neurodevelopmental Delay Diagnosis Rates Are Increased in a Region with Aerial Pesticide Application.

A number of studies have implicated pesticides in childhood developmental delay (DD) and autism spectrum disorder (ASD). The influence of the route of pesticide exposure on neurodevelopmental delay is not well defined. To study this factor, we examined ASD/DD diagnoses rates in an area near our regional medical center that employs yearly aerial pyrethroid pesticide applications to combat mosquito-borne encephalitis. The aim of this study was to determine if areas with aerial pesticide exposure had higher rates of ASD/DD diagnoses. This regional study identified higher rates of ASD/DD diagnoses in an area with aerial pesticides application. Zip codes with aerial pyrethroid exposure were 37% more likely to have higher rates of ASD/DD (adjusted RR = 1.37, 95% CI = 1.06-1.78, p = 0.02). A Poisson regression model controlling for regional characteristics (poverty, pesticide use, population density, and distance to medical center), subject characteristics (race and sex), and local birth characteristics (prematurity, low birthweight, and birth rates) identified a significant relationship between aerial pesticide use and ASD/DD rates. The relationship between pesticide application and human neurodevelopment deserves additional study to develop safe and effective methods of mosquito prevention, particularly as communities develop plans for Zika virus control.

Infectious DNAs derived from insect-specific flavivirus genomes enable identification of pre- and post-entry host restrictions in vertebrate cells.

Flaviviruses such as West Nile virus (WNV), dengue virus and Zika virus are mosquito-borne pathogens that cause significant human diseases. A novel group of insect-specific flaviviruses (ISFs), which only replicate in mosquitoes, have also been identified. However, little is known about the mechanisms of ISF host restriction. We report the generation of infectious cDNA from two Australian ISFs, Parramatta River virus (PaRV) and Palm Creek virus (PCV). Using circular polymerase extension cloning (CPEC) with a modified OpIE2 insect promoter, infectious cDNA was generated and transfected directly into mosquito cells to produce infectious virus indistinguishable from wild-type virus. When infectious PaRV cDNA under transcriptional control of a mammalian promoter was used to transfect mouse embryo fibroblasts, the virus failed to initiate replication even when cell entry steps were by-passed and the type I interferon response was lacking. We also used CPEC to generate viable chimeric viruses between PCV and WNV. Analysis of these hybrid viruses revealed that ISFs are also restricted from replication in vertebrate cells at the point of entry. The approaches described here to generate infectious ISF DNAs and chimeric viruses provide unique tools to further dissect the mechanisms of their host restriction.

Pigsties near dwellings as a potential risk factor for the prevalence of Japanese encephalitis virus in adult in Shanxi, China.

The increasing trend of adult cases of Japanese encephalitis (JE) in China, particularly in northern China, has become an important public health issue. We conducted an epidemiological investigation in the south of Shanxi Province to examine the relationships between mosquitoes, Japanese encephalitis virus (JEV), and adult JE cases.

An Integrative Eco-Epidemiological Analysis of West Nile Virus Transmission.

West Nile disease, caused by the West Nile virus (WNV), is a mosquito-borne zoonotic disease affecting humans and horses that involves wild birds as amplifying hosts. The mechanisms of WNV transmission remain unclear in Europe where the occurrence of outbreaks has dramatically increased in recent years. We used a dataset on the competence, distribution, abundance, diversity and dispersal of wild bird hosts and mosquito vectors to test alternative hypotheses concerning the transmission of WNV in Southern France. We modelled the successive processes of introduction, amplification, dispersal and spillover of WNV to incidental hosts based on host-vector contact rates on various land cover types and over four seasons. We evaluated the relative importance of the mechanisms tested using two independent serological datasets of WNV antibodies collected in wild birds and horses. We found that the same transmission processes (seasonal virus introduction by migratory birds, Culex modestus mosquitoes as amplifying vectors, heterogeneity in avian host competence, absence of 'dilution effect') best explain the spatial variations in WNV seroprevalence in the two serological datasets. Our results provide new insights on the pathways of WNV introduction, amplification and spillover and the contribution of bird and mosquito species to WNV transmission in Southern France.

Is Zika Virus an Emerging TORCH Agent? An Invited Commentary.

Zika virus (ZIKV) is a mosquito-borne arbovirus from the family Flaviviridae, which had caused some epidemics since its discovery in 1947 without any significant impacts on public health. In 2015, however, a 20-fold increase in congenital microcephaly cases in northeastern Brazil was attributed to prenatally acquired ZIKV infection. Traditionally, TORCH agents have 4 common characteristics including causing a mild illness in infected mother, vertical transmission to fetus, developing several anomalies in the affected fetus, and in some instances, maternal therapy may not ameliorate fetal prognosis. Prenatal ZIKV infection has shown the aforementioned characteristics during the recent epidemics in South America and the Caribbean region; therefore, it should be considered as an emerging TORCH agent that may seriously threaten public health. Fetal ultrasound can be used as a safe, inexpensive, and easy-to-access imaging modality for detecting suspicious cases of congenital Zika syndrome in utero and suggesting confirmatory diagnostic examinations to these patients.

Trends of Dengue Disease Epidemiology.

Dengue disease is an emerging mosquito-borne viral infection transmitted between humans by Aedes spp. that are distributed mainly in the tropical and subtropical region along with chikungunya and zika diseases. The distribution of dengue disease is influenced by local variation, such as geography, rainfall, temperature, and rapid urbanization or migration. The epidemy of mosquito-borne infection significantly led to increased number of cases and hyperendemicity which induce a more severe form of dengue accompanied by cocirculation of chikungunya and zika. The rapid global spreading of dengue disease created public health burdens that are presently unfulfilled by the absence of specific therapy, simple diagnosis tool for the early phase, and effective and efficient vector control system. This review highlights the current situation of dengue distribution, epidemiology, and new strategies for early dengue diagnosis and risk prediction of severity that can be used to improve oversight and alleviate the heavy burden of the disease.

Infections of Wolbachia may destabilize mosquito population dynamics.

Recent efforts in controlling mosquito-borne diseases focus on biocontrol strategies that incapacitate pathogens inside mosquitoes by altering the mosquito's microbiome. A case in point is the introduction of Wolbachia into natural mosquito populations in order to eliminate Dengue virus. However, whether this strategy can successfully control vector-borne diseases is debated; particularly, how artificial infection affects population dynamics of hosts remains unclear. Here, we show that natural Wolbachia infections are associated with unstable mosquito population dynamics by contrasting Wolbachia-infected versus uninfected cage populations of the Asian tiger mosquito (Aedes albopictus). By analyzing weekly data of adult mosquito abundances, we found that the variability of the infected populations is significantly higher than that of the uninfected. The elevated population variability is explained by increased instability in dynamics, as quantified by system nonlinearity (i.e., state-dependence). In addition, predictability of infected populations is substantially lower. A mathematical model analysis suggests that Wolbachia may alter mosquito population dynamics by modifying larval competition of hosts. These results encourage examination for effects of artificial Wolbachia establishment on mosquito populations, because an enhancement of population variability with reduced predictability could pose challenges in management. Our findings have implications for application of microbiome alterations in biocontrol programs.