Zika Virus in the Americas--Yet Another Arbovirus Threat

Zika knowledge and prevention practices among U.S. travelers: a large cross-sectional survey study

BACKGROUND

The aim of this study was to investigate what factors predict knowledge about Zika transmission, symptomology, and treatment among U.S. travelers and, additionally, to evaluate how Zika knowledge influences the adoption of personal protective behaviors.

METHODS

Data were collected as part of a cross-sectional survey study using a probability-based internet panel of U.S. travelers in June 2017. We ran logistic regression models of factors predicting Zika knowledge (high vs. low) and of knowledge predicting adoption of personal protective measures.

RESULTS

We found that traveling to a Zika endemic country and travelers' gender were both significantly predictive of higher Zika knowledge (odds ratio (OR): 1.48, 95% confidence interval (CI): 1.14-1.93 and OR: 1.44, 95% CI: 1.08-1.92), adjusting for age, race, education, income, and trip purpose. Additionally, among travelers to Zika endemic countries, individuals with higher Zika knowledge had significantly higher odds of engaging in preventive behaviors compared to those with lower knowledge. However, few travelers knew about the sexual transmission of Zika and adopted sexual prevention measures.

CONCLUSIONS

Our findings suggest that there are gaps in knowledge about the risks and transmission of Zika and travelers with low knowledge are less likely to engage in the appropriate prevention methods. Significantly, few U.S. travelers have knowledge of the sexual transmission of Zika and, accordingly, there is less overall engagement with prevention measures for this transmission mechanism than for vector-borne transmission.

Characteristics and preparation of the last-minute traveler: analysis of vaccine usage in the Global TravEpiNet Consortium

BACKGROUND

Last-minute travellers (LMTs) present challenges for health care providers because they may have insufficient time for recommended vaccinations or pre-travel preparation. Our objective was to obtain a better understanding of LMTs in order to help travel medicine providers develop improved strategies to decrease the number of LMTs and potentially reduce travel-related morbidity.

METHODS

We defined LMTs as travellers with a departure date of 7 days or fewer from the medical encounter. We analysed the characteristics and health preparation of 12 494 LMTs who presented to a network of US clinical practices for pre-travel health advice between January 2009 and December 2015.

RESULTS

LMTs comprised 16% of all travellers. More LMTs than non-LMTs travelled for business or to visit friends and relatives (VFR) (26% vs 16% and 15% vs 8%, respectively; P < 0.0001). More LMTs also travelled for longer than 1 month (27% vs 21%; P < 0.0001) and visited only urban areas (40% vs 29%; P < 0.0001). At least one travel vaccine was deferred by 18% of LMTs because of insufficient time before departure. Vaccines that required multiple vaccinations, such as Japanese encephalitis and rabies, were the most likely to be deferred because of time constraints.

CONCLUSION

Interventions to improve the timing of pre-travel health consultations should be developed, particularly for business and VFR travellers. Recently endorsed accelerated vaccine schedules for Japanese encephalitis and rabies may help some LMTs receive protection against these infections despite late presentation for pre-travel health care.

Structures of enveloped virions determined by cryogenic electron microscopy and tomography

Enveloped viruses enclose their genomes inside a lipid bilayer which is decorated by membrane proteins that mediate virus entry. These viruses display a wide range of sizes, morphologies and symmetries. Spherical viruses are often isometric and their envelope proteins follow icosahedral symmetry. Filamentous and pleomorphic viruses lack such global symmetry but their surface proteins may display locally ordered assemblies. Determining the structures of enveloped viruses, including the envelope proteins and their protein-protein interactions on the viral surface, is of paramount importance. These structures can reveal how the virions are assembled and released by budding from the infected host cell, how the progeny virions infect new cells by membrane fusion, and how antibodies bind surface epitopes to block infection. In this chapter, we discuss the uses of cryogenic electron microscopy (cryo-EM) in elucidating structures of enveloped virions. Starting from a detailed outline of data collection and processing strategies, we highlight how cryo-EM has been successfully utilized to provide unique insights into enveloped virus entry, assembly, and neutralization.

International prospective observational cohort study of Zika in infants and pregnancy (ZIP study): study protocol

BACKGROUND

Until recently, Zika virus (ZIKV) infections were considered mild and self-limiting. Since 2015, they have been associated with an increase in microcephaly and other birth defects in newborns. While this association has been observed in case reports and epidemiological studies, the nature and extent of the relationship between ZIKV and adverse pregnancy and pediatric health outcomes is not well understood. With the unique opportunity to prospectively explore the full spectrum of issues related to ZIKV exposure during pregnancy, we undertook a multi-country, prospective cohort study to evaluate the association between ZIKV and pregnancy, neonatal, and infant outcomes.

METHODS

At research sites in ZIKV endemic regions of Brazil (4 sites), Colombia, Guatemala, Nicaragua, Puerto Rico (2 sites), and Peru, up to 10,000 pregnant women will be recruited and consented in the first and early second trimesters of pregnancy and then followed through delivery up to 6 weeks post-partum; their infants will be followed until at least 1 year of age. Pregnant women with symptomatic ZIKV infection confirmed by presence of ZIKV RNA and/or IgM for ZIKV will also be enrolled, regardless of gestational age. Participants will be tested monthly for ZIKV infection; additional demographic, physical, laboratory and environmental data will be collected to assess the potential interaction of these variables with ZIKV infection. Delivery outcomes and detailed infant assessments, including physical and neurological outcomes, will be obtained.

DISCUSSION

With the emergence of ZIKV in the Americas and its association with adverse pregnancy outcomes in this region, a much better understanding of the spectrum of clinical outcomes associated with exposure to ZIKV during pregnancy is needed. This cohort study will provide information about maternal, fetal, and infant outcomes related to ZIKV infection, including congenital ZIKV syndrome, and manifestations that are not detectable at birth but may appear during the first year of life. In addition, the flexibility of the study design has provided an opportunity to modify study parameters in real time to provide rigorous research data to answer the most critical questions about the impact of congenital ZIKV exposure.

TRIAL REGISTRATION

NCT02856984 . Registered August 5, 2016. Retrospectively registered.

A yellow flag on the horizon: The looming threat of yellow fever to North America

OBJECTIVES

Yellow fever virus historically was a frequent threat to American and European coasts. Medical milestones such as the discovery of mosquitoes as vectors and subsequently an effective vaccine significantly reduced its incidence, in spite of which, thousands of cases of this deathly disease still occur regularly in Sub-Saharan Africa and the Amazonian basin in South America, which are usually not reported. An urban outbreak in Angola, consecutive years of increasing incidence near major Brazilian cities, and imported cases in China, South America and Europe, have brought this virus back to the global spotlight. The aim of this article is to underline that the preventive YFV measures, such as vaccination, need to be carefully revised in order to minimize the risks of new YFV outbreaks, especially in urban or immunologically vulnerable places. Furthermore, this article highlights the diverse factors that have favored the spread of other Aedes spp.-associated arboviral diseases like Dengue, Chikungunya and Zika, to northern latitudes causing epidemics in the United States and Europe, emphasizing the possibility that YFV might follow the path of these viruses unless enhanced surveillance and efficient control systems are urgently initiated.

Low to medium-low risk perception for dengue, chikungunya and Zika outbreaks by infectious diseases physicians in France, Western Europe

Background

Many tropical countries are currently experiencing dengue (DEN), chikungunya (CHIK) and also more recently Zika (ZIKA) epidemics (particularly in Latin America). Although the risk of transmission and spread of these infections in temperate regions remains a controversial issue, vector-borne diseases have been widely reported in the media and have been the focus of preventive strategies by national and international policy-makers and public health authorities. In this context, we wanted to determine the extent of risk perception in infectious diseases (ID) physicians of the current and future risk of arboviral disease introduction, autochthonous case development and epidemic scenarios in France, Western Europe.

Methods

To this aim, we developed an original standardized questionnaire survey which was disseminated by the French Infectious Diseases Society to ID physician members.

Results

We found that ID physicians perceived the risk of introduction and outbreak development of DEN, CHIK and ZIKA in France to be low to medium-low. Generalized Linear Model(s) identified medical school training, the extent of professional experience, and awareness of the French national plan regarding arboviral infections as significant predictors for lower risk perception among respondents.

Conclusion

Despite the fact that arboviral diseases are increasingly being imported into France, sometimes resulting in sporadic autochtonous transmission, French ID physicians do not perceive the risk as high. Better communication and education targeting health professionals and citizens will be needed to enhance the effectiveness of the French national plan to prepare against arboviral diseases.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7317-9) contains supplementary material, which is available to authorized users.

A path model of psychosocial constructs predicting future Zika vaccine uptake intent

OBJECTIVE

The recent Zika virus outbreak, while no longer an international public health emergency, is still a serious threat, particularly to pregnant women and babies born to pregnant women infected with the virus. This study examined the predictive effects of psychosocial constructs on self-reported intent to get a future Zika vaccine among women of reproductive age.

METHODS

Data were collected using an online survey with a representative sample of 339 women ages 18-49 from the continental United States. The survey addressed variables originating with the Extended Parallel Processing Model (EPPM) as related to future Zika vaccine uptake intent.

RESULTS

Three quarters of all respondents reported intention to get a future Zika vaccine. Path modeling revealed a direct effect of perceived susceptibility, self-efficacy, and response efficacy on future Zika vaccine uptake intent, as well as an indirect effect of perceived susceptibility through both self-efficacy and response efficacy. In addition, the final model showed an indirect effect of perceived severity on Zika vaccine uptake intent through self-efficacy and response efficacy and accounted for 54.6% of the variance in vaccination intent.

CONCLUSIONS

These findings have implications for future Zika vaccine promotion campaigns. This study confirms the importance of perceived susceptibility, self-efficacy, and response efficacy for use in Zika vaccine uptake campaigns; in addition, when using perceived severity, both self-efficacy and response efficacy should be considered in message design.

Zika Virus Epidemic in Pregnant Women, Dominican Republic, 2016-2017

During the epidemic, almost 10% of pregnancies in acute infection resulted in fetal loss; 3 cases of fetal microcephaly were reported.

Zika virus infection during pregnancy may result in birth defects and pregnancy complications. We describe the Zika virus outbreak in pregnant women in the Dominican Republic during 2016–2017. We conducted multinomial logistic regression to identify factors associated with fetal losses and preterm birth. The Ministry of Health identified 1,282 pregnant women with suspected Zika virus infection, a substantial proportion during their first trimester. Fetal loss was reported for ≈10% of the reported pregnancies, and 3 cases of fetal microcephaly were reported. Women infected during the first trimester were more likely to have early fetal loss (adjusted odds ratio 5.9, 95% CI 3.5–10.0). Experiencing fever during infection was associated with increased odds of premature birth (adjusted odds ratio 1.65, 95% CI 1.03–2.65). There was widespread morbidity during the epidemic. Our findings strengthen the evidence for a broad range of adverse pregnancy outcomes resulting from Zika virus infection.

Zika Vaccine Development-Current Progress and Challenges for the Future

Zika virus is an emergent pathogen that gained significant importance during the epidemic in South and Central America as unusual and alarming complications of infection were recognized. Although initially considered a self-limited benign infection, a panoply of neurologic complications were recognized including a Guillain-Barré-like syndrome and in-utero fetal infection causing microcephaly, blindness, and other congenital neurologic complications. Numerous Zika virus vaccines were developed, with nine different vaccines representing five different platforms entered into clinical trials, one progressing to Phase II. Here we review the current landscape and challenges confronting Zika virus vaccine development.

Environmental Politics of Reproduction

What constitutes "human reproduction" is under negotiation as its biology, social nature, and cultural valences are increasingly perceived as bound up in environmental issues. This review maps the growing overlap between formerly rather separate domains of reproductive politics and environmental politics, examining three interrelated areas. The first is the emergence of an intersectional environmental reproductive justice framework in activism and environmental health science. The second is the biomedical delineation of the environment of reproduction and development as an object of growing research and intervention, as well as the marking off of early-life environments as an "exposed biology" consequential to the entire life span. Third is researchers' critical engagement with the reproductive subject of environmental politics and the lived experience of reproduction in environmentally dystopic times. Efforts to rethink the intersections of reproductive and environmental politics are found throughout these three areas.

The reaction mechanism of Zika virus NS2B/NS3 serine protease inhibition by dipeptidyl aldehyde: a QM/MM study

Zika virus (ZIKV) infection has become a global public health problem, associated with microcephaly in newborns and Guillain-Barré syndrome in adults. Currently, there are no commercially available anti-ZIKV drugs. The viral protease NS2B/NS3, which is involved in viral replication and maturation, is a potential drug target. Peptidomimetic aldehyde inhibitors bind covalently to the catalytic S135 of the NS3 protease. Here, we apply hybrid quantum mechanics/molecular mechanics (QM/MM) free-energy simulations at the PDDG-PM3/ff14SB level to investigate the inhibition mechanism of the ZIKV protease by a dipeptidyl aldehyde inhibitor (acyl-KR-aldehyde). The results show that proton transfer from the catalytic S135 to H51 occurs in concert with nucleophilic addition on the aldehyde warhead by S135. The anionic covalent complex between the dipeptidyl aldehyde and the ZIKV protease is analogous to the tetrahedral intermediate for substrate hydrolysis. Spontaneous protonation by H51 forms the hemiacetal. In addition, we use correlated ab initio QM/MM potential energy path calculations at levels up to LCCSD(T)/(aug)-cc-pVTZ to obtain accurate potential energy profiles of the reaction, which also support a concerted mechanism. These results provide detailed insight into the mechanism of ZIKV protease inhibition by a peptidyl aldehyde inhibitor, which will guide in the design of inhibitors.

A Mosquito Workshop and Community Intervention: A Pilot Education Campaign to Identify Risk Factors Associated with Container Mosquitoes in San Pedro Sula, Honduras

Dengue poses a significant public health threat and results in ~96 million clinical cases every year. Central America is a region burdened by neglected tropical diseases, including dengue. The primary vectors of dengue, Aedes aegypti and Aedes albopictus, are widely distributed in Honduras. Additionally, sustained and consistent mosquito control is lacking in the country. Successful control of container mosquitoes relies heavily on participation from community leaders, stakeholders, and the community itself. We conducted a pilot study in San Pedro Sula, Honduras where community leaders and stakeholders were trained on mosquito biology and control and were able to apply that knowledge to an underserved community in San Pedro Sula. Surveys to assess the number and type of containers in the community and the number of containers on the residence identified associations with select socioeconomic factors and other variables based on survey questions. The average number of containers on the premises was 15 (± 2.3) and the most prevalent containers (>50%) were flowerpots, garbage, and toys, which could be targeted in mosquito control programs. This pilot study offers a framework for training community leaders and stakeholders to create a sustainable community-based vector control program for container mosquitoes.

In Vitro Antiviral Activity Against Zika Virus From a Natural Product of the Brazilian Brown Seaweed Dictyota menstrualis

Natural products isolated from seaweeds have shown great antiviral potential against numerous viruses such as human type 1 herpes, human immunodeficiency virus, and dengue. Diterpenes produced by the brown seaweeds Dictyota and Canistrocarpus, in particular, have shown antiviral or virucidal activity. Recently, the Zika virus (ZIKV) has become a major public health concern due to its widespread dissemination throughout the Americas. Since no vaccines are available, and no drugs have effectively treated recent cases of infection, our group evaluated products from Dictyota menstrualis for their antiviral potential, alone and in combination with Ribavirin. We first evaluated the compounds’ cytotoxicity at high concentrations, and then evaluated the inhibition of ZIKV replication by crude extracts and acetylated crude extracts and their fractions at 20 μg/mL. The F-6 and FAc-2 fractions, rich in cyclic diterpenes with aldehyde groupings, inhibited ZIKV replication by >74%, with inhibition behaving in a dose-dependent manner and the 50% effective concentration (EC50) values of 2.80 (F-6) and 0.81 (FAc-2) μg/mL. Regarding the mechanism of action, FAc-2 had strong virucidal potential, and F-6 inhibited viral adsorption. Associating FAc-2 with Ribavirin at suboptimal dosages produced a strong synergistic effect that completely inhibited viral replication. Our results indicate that these natural products have excellent inhibitory potential against ZIKV replication and may be promising for developing affective therapies.

Comparison of Genetic Variations in Zika Virus Isolated From Different Geographic Regions

The Zika virus (ZIKV) belongs to the genus Flavivirus, together with Dengue virus, yellow fever virus, and West Nile virus. The virus, which was first found in Africa in 1947, has spread across the world owing to a lack of effective drugs or vaccines. The complete genome sequence of ZIKV is now available; it includes three structural and seven non-structure genes arranged in the order of capsid, pre-membrane, envelope, NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5. Two geographically distinct lineages are known, i.e., Asian and African, but ZIKV exhibits differences in clinical progression among regions.

An update on the aspects of Zika virus infection on male reproductive system

Zika virus (ZIKV) is mainly transmitted through Aedes mosquito bites, but sexual and post-transfusion transmissions have been reported. During acute infection, ZIKV is detectable in most organs and body fluids including human semen. Although it is not currently epidemic, there is a concern that the virus can still reemerge since the male genital tract might harbor persistent reservoirs that could facilitate viral transmission over extended periods, raising concerns among public health and assisted reproductive technologies (ART) experts and professionals. So far, the consensus is that ZIKV infection in the testes or epididymis might affect sperm development and, consequently, male fertility. Still, diagnostic tests have not yet been adapted to resource-restricted countries. This manuscript provides an updated overview of the cellular and molecular mechanisms of ZIKV infection and reviews data on ZIKV persistence in semen and associated risks to the male reproductive system described in human and animal models studies. We provide an updated summary of the impact of the recent ZIKV outbreak on human-ART, weighing on current recommendations and diagnostic approaches, both available and prospective, with special emphasis on mass spectrometry-based biomarker discovery. In the light of the identified gaps in our accumulated knowledge on the subject, we highlight the importance for couples seeking ART to follow the constantly revised guidelines and the need of specific ZIKV diagnosis tools for semen screening to contain ZIKV virus spread and make ART safer.

Assessing Zika Virus Transmission Within Households During an Outbreak in Martinique, 2015-2016

Since 2015, Zika virus (ZIKV) has caused large epidemics in the Americas. Households are natural targets for control interventions, but quantification of the contribution of household transmission to overall spread is needed to guide policy. We developed a modeling framework to evaluate this contribution and key epidemic features of the ZIKV epidemic in Martinique in 2015-2016 from the joint analysis of a household transmission study (n = 68 households), a study among symptomatic pregnant women (n = 281), and seroprevalence surveys of blood donors (n = 457). We estimated that the probability of mosquito-mediated within-household transmission (from an infected member to a susceptible one) was 21% (95% credible interval (CrI): 5, 51), and the overall probability of infection from outside the household (i.e., in the community) was 39% (95% CrI: 27, 50). Overall, 50% (95% CrI: 43, 58) of the population was infected, with 22% (95% CrI: 5, 46) of infections acquired in households and 40% (95% CrI: 23, 56) being asymptomatic. The probability of presenting with Zika-like symptoms due to another cause was 16% (95% CrI: 10, 23). This study characterized the contribution of household transmission in ZIKV epidemics, demonstrating the benefits of integrating multiple data sets to gain more insight into epidemic dynamics.

Synergistic terpene combinations as larvicides against the dengue vector Aedes aegypti Linn

Most of the essential oils (EO) known for mosquitocidal activity contain terpenes as part of their chemical constituents. In this study, four monoterpenes namely γ-terpinene (T), R-(+)-limonene (L), carvacrol (C), and trans-anethole (A) were screened against late third instar Aedes aegypti Linn. larvae singly and in combination to find out the synergistic interaction. The monoterpenes γ-terpinene, R-(+)-limonene, trans-anethole, and carvacrol showed larvicidal activity with LC₅₀ values of 9.76, 11.88, 50.19, 48.57 ppm and LC₉₀ values of 16.99, 17.78, 65.21, 75.02 ppm, respectively for Ae. aegypti when tested individually. Prepared binary combinations at LC₂₀ values and studied the synergistic interactions based on cotoxicity factor (CTF) and found that all the binary combinations showed synergistic interactions (CTF > 20). Further, the binary (1:1), ternary (1:1:1), and quaternary (1:1:1:1) terpene combinations on equal weight basis were prepared, evaluated against Ae. aegypti larvae and synergistic interactions were studied by Wadley's method. Among the eight combinations two combinations viz. LC (LC₅₀ 10.42 ppm) and LA (LC₅₀ 11.86 ppm) were showing synergistic interactions (R > 1.5) and others were exhibiting additive effect (1.5 ≥ R > 0.5) and none of the combinations showed antagonism (R < 0.5). Among the two methods used the Wadley's method found suitable when combinations were made on an equal weight basis. The two binary combinations found in this study are promising synergistic mixtures which has scope in designing mosquito larvicidal EOs by enriching the EOs with terpenes or by producing EO combinations with these terpenes as chemical constituents in the correct proportions.

Community Composition and Year-round Abundance of Vector Species of Mosquitoes make Miami-Dade County, Florida a Receptive Gateway for Arbovirus entry to the United States

Vector-borne diseases are a heavy burden to human-kind. Global warming and urbanization have a significant impact on vector-borne disease transmission, resulting in more severe outbreaks, and outbreaks in formerly non-endemic areas. Miami-Dade County, Florida was the most affected area in the continental United States during the 2016 Zika virus outbreak. Miami is an important gateway and has suitable conditions for mosquitoes year-round. Therefore, it was critical to establish and validate a surveillance system to guide and improve mosquito control operations. Here we assess two years of mosquito surveillance in Miami established after the 2016 Zika virus outbreak. Our results show that the most abundant mosquito species are either well adapted to urban environments or are adapting to it. The five most abundant species comprised 85% of all specimens collected, with four of them being primary vectors of arboviruses. Aedes aegypti and Culex quinquefasciatus were found year-round throughout Miami regardless of urbanization level, vegetation, or socioeconomic variations. This study serves as a foundation for future efforts to improve mosquito surveillance and control operations.

Development of a Specific CHIKV-E2 Monoclonal Antibody for Chikungunya Diagnosis

Chikungunya fever is a vector-borne viral disease transmitted to humans by chikungunya virus (CHIKV)-infected mosquitoes. There have been many outbreaks of CHIKV infection worldwide, and the virus poses ongoing risks to global health. To prevent and control CHIKV infection, it is important to improve the current CHIKV diagnostic approaches to allow for the detection of low CHIKV concentrations and to correctly distinguish CHIKV infections from those due to other mosquito-transmitted viruses, including dengue virus (DENV), Japanese encephalitis virus (JEV), and Zika virus (ZIKV). Here, we produced monoclonal antibodies (mAbs) against the CHIKV envelope 2 protein (CHIKV-E2) and compared their sensitivity and specificity with commercially available mAbs using enzyme-linked immunosorbent assays (ELISA). Two anti-CHIKV-E2 mAbs, 19-1 and 21-1, showed higher binding affinities to CHIKV-E2 protein than the commercial mAbs did. In particular, the 19-1 mAb had the strongest binding affinity to inactivated CHIKV. Moreover, the 19-1 mAb had very little cross-reactivity with other mosquito-borne viruses, such as ZIKV, JEV, and DENV. These results suggest that the newly produced anti-CHIKV-E2 mAb, 19-1, could be used for CHIKV diagnostic approaches.

Use of Twitter data to improve Zika virus surveillance in the United States during the 2016 epidemic

BACKGROUND

Zika virus (ZIKV) is an emerging mosquito-borne arbovirus that can produce serious public health consequences. In 2016, ZIKV caused an epidemic in many countries around the world, including the United States. ZIKV surveillance and vector control is essential to combating future epidemics. However, challenges relating to the timely publication of case reports significantly limit the effectiveness of current surveillance methods. In many countries with poor infrastructure, established systems for case reporting often do not exist. Previous studies investigating the H1N1 pandemic, general influenza and the recent Ebola outbreak have demonstrated that time- and geo-tagged Twitter data, which is immediately available, can be utilized to overcome these limitations.

METHODS

In this study, we employed a recently developed system called Cloudberry to filter a random sample of Twitter data to investigate the feasibility of using such data for ZIKV epidemic tracking on a national and state (Florida) level. Two auto-regressive models were calibrated using weekly ZIKV case counts and zika tweets in order to estimate weekly ZIKV cases 1 week in advance.

RESULTS

While models tended to over-predict at low case counts and under-predict at extreme high counts, a comparison of predicted versus observed weekly ZIKV case counts following model calibration demonstrated overall reasonable predictive accuracy, with an R2 of 0.74 for the Florida model and 0.70 for the U.S.

MODEL

Time-series analysis of predicted and observed ZIKV cases following internal cross-validation exhibited very similar patterns, demonstrating reasonable model performance. Spatially, the distribution of cumulative ZIKV case counts (local- & travel-related) and zika tweets across all 50 U.S. states showed a high correlation (r = 0.73) after adjusting for population.

CONCLUSIONS

This study demonstrates the value of utilizing Twitter data for the purposes of disease surveillance. This is of high value to epidemiologist and public health officials charged with protecting the public during future outbreaks.

Estimating Past, Present, and Future Trends in the Global Distribution and Abundance of the Arbovirus Vector Aedes aegypti Under Climate Change Scenarios

Background:Aedes aegypti is the principal vector for several important arbovirus diseases, including dengue, chikungunya, yellow fever, and Zika. While recent empirical research has attempted to identify the current global distribution of the vector, the seasonal, and longer-term dynamics of the mosquito in response to trends in climate, population, and economic development over the twentieth and the twenty-first century remains to be elucidated.

Methods: In this study, we use a process-based mathematical model to estimate global vector distribution and abundance. The model is based on the lifecycle of the vector and its dependence on climate, and the model sensitivity to socio-economic development is tested. Model parameters were generally empirically based, and the model was calibrated to global databases and time series of occurrence and abundance records. Climate data on temperature and rainfall were taken from CRU TS3.25 (1901–2015) and five global circulation models (CMIP5; 2006–2099) forced by a high-end (RCP8.5) and a low-end (RCP2.6) emission scenario. Socio-economic data on global GDP and human population density were from ISIMIP (1950–2099).

Findings: The change in the potential of global abundance in A. aegypti over the last century up to today is estimated to be an increase of 9.5% globally and a further increase of 20 or 30% by the end of this century under a low compared to a high carbon emission future, respectively. The largest increase has occurred in the last two decades, indicating a tipping point in climate-driven global abundance which will be stabilized at the earliest in the mid-twenty-first century. The realized abundance is estimated to be sensitive to socioeconomic development.

Interpretation: Our data indicate that climate change mitigation, i.e., following the Paris Agreement, could considerably help in suppressing risks of increased abundance and emergence of A. aegypti globally in the second half of the twenty-first century.

Zika and Chikungunya Virus and Risk for Venous Thromboembolism

A variety of viral infections are associated with hypercoagulable states and may be linked to the development of deep venous thrombosis and pulmonary embolism. The Zika and Chikungunya viral infections spread through the South and Central American continents, moving to North America in 2016, with severe cases of polyarthralgia, fever, and Guillain-Barré syndrome leading eventually to death. A decreased trend for both infections was reported in the first quarter of 2017. In this article, we report the possible association of venous thromboembolic events associated with Zika infection. After 2 cases of deep venous thrombosis in patients with acute Zika infections, D-dimer levels were measured in 172 consecutive patients who presented to the emergency department of a university hospital in an endemic region of Brazil with either Zika or Chikungunya infections confirmed by polymerase chain reaction tests. D-dimer levels were increased in 19.4% of 31 patients with Zika and in 63.8% of 141 patients with Chikungunya infections. The mechanisms behind this association are yet to be elucidated as well as the potential for venous thromboembolism prevention strategies for in-hospital patients affected by Zika and Chikungunya infections.

Vapor delivery of plant essential oils alters pyrethroid efficacy and detoxification enzyme activity in mosquitoes

The use of synthetic insecticides to limit the spread of mosquito-borne disease faces a number of significant challenges, including insecticide resistance, concerns related to the environmental impact of widespread insecticide use, as well as slowed development of new insecticide chemistries. One important alternative to broadcast insecticides is the use of personal protection strategies to limit contact with vector species, including the use of spatial repellents that can employ synthetic pyrethroids or botanical products to effect control. A currently underexplored area of research involves the investigation of botanical products for their potential to serve as insecticide synergists when delivered as a vapor. This study describes the development of an assay that facilitates the screening of essential oils delivered as a vapor for enhancement of deltamethrin efficacy in both pyrethroid-susceptible and -resistant strains of the vector mosquito species Aedes aegypti. Deltamethrin efficacy was significantly increased following exposure to cinnamon (Cinnamomum cassia), tagetes (Tagetes bipinnata), and sage (Salvia officinalis) oils, while efficacy was significantly decreased following exposure to amyris (Amyris balsamifera) oil. These effects appeared to be mediated by changes in cytochrome P450 activity. This work demonstrates that some plant-derived essential oils delivered as a vapor are capable of increasing the efficacy of deltamethrin similar to classical synergists such as piperonyl butoxide, supporting the use of a real world delivery method instead of traditional contact exposure studies.

Expanding the canon: Non-classical mosquito genes at the interface of arboviral infection

Mosquito transmitted viruses cause significant morbidity and mortality in human populations. Despite the use of insecticides and other measures of vector control, arboviral diseases are on the rise. One potential solution for limiting disease transmission to humans is to render mosquitoes refractory to viral infection through genetic modification. Substantial research effort in Drosophila, Aedes and Anopheles has helped to define the major innate immune pathways, including Toll, IMD, Jak/Stat and RNAi, however we still have an incomplete picture of the mosquito antiviral response. Transcriptional profiles of virus-infected insects reveal a much wider range of pathways activated by the process of infection. Within these lists of genes are unexplored mosquito candidates of viral defense. Wolbachia species are endosymbiotic bacteria that naturally limit arboviral infection in mosquitoes. Our understanding of the Wolbachia-mediated viral blocking mechanism is poor, but it does not appear to operate via the classical immune pathways. Herein, we reviewed the transcriptomic response of mosquitoes to multiple viral species and put forth consensus gene types/families outside the immune canon whose expression responds to infection, including cytoskeleton and cellular trafficking, the heat shock response, cytochromes P450, cell proliferation, chitin and small RNAs. We then examine emerging evidence for their functional role in viral resistance in diverse insect and mammalian hosts and their potential role in Wolbachia-mediated viral blocking. These candidate gene families offer novel avenues for research into the nature of insect viral defense.

Predicting aquatic development and mortality rates of Aedes aegypti

Mosquito-borne pathogens continue to be a significant burden within human populations, with Aedes aegypti continuing to spread dengue, chikungunya, and Zika virus throughout the world. Using data from a previously conducted study, a linear regression model was constructed to predict the aquatic development rates based on the average temperature, temperature fluctuation range, and larval density. Additional experiments were conducted with different parameters of average temperature and larval density to validate the model. Using a paired t-test, the model predictions were compared to experimental data and showed that the prediction models were not significantly different for average pupation rate, adult emergence rate, and juvenile mortality rate. The models developed will be useful for modeling and estimating the upper limit of the number of Aedes aegypti in the environment under different temperature, diurnal temperature variations, and larval densities.

Epidemiological characteristics of a Zika outbreak in Portoviejo, Ecuador, 2016

Objective

To estimate the number and percentage of cases with Zika diagnosis at a hospital in Portoviejo, Manabí, Ecuador.

Methods

This was a hospital-based, retrospective, observational, descriptive, cross-sectional study conducted at the Dr. Verdi Cevallos Balda Hospital from January – August 2016. A secondary analysis of a database was performed to estimate the number and percentage of patients positive for Zika virus, by sex, age group, ethnicity, and type of medical care. Prevalence and odds ratios with 95% Confidence Intervals were calculated using the Mantel and Haenszel method. Laboratory diagnostics included assays for the detection of Zika, chikungunya, dengue, and others.

Results

In all, 467 suspected cases of Zika were identified based on clinical criteria. Of these, 148 cases (31.7%) were confirmed by detection of ZIKV RNA. The peak of the outbreak was documented in May – July 2016 during the rainy season, following the earthquake of April 2016. The adjusted odds ratios indicated that Zika virus was less likely in men and in subjects < 20 years of age. Most of the infected pregnant women (61%) were in the second trimester of pregnancy. No cases of microcephaly were reported.

Conclusions

Because Zika was more likely to occur among women and those ≥ 20 years of age, surveillance of these groups is imperative to avoid transmission to newborns. Future studies that address the research gap and inform the country's Zika control efforts are recommended.

Predictors of mortality in patients with yellow fever: an observational cohort study

BACKGROUND

Yellow fever virus infection results in death in around 30% of symptomatic individuals. The aim of this study was to identify predictors of death measured at hospital admission in a cohort of patients admitted to hospital during the 2018 outbreak of yellow fever in the outskirts of São Paulo city, Brazil.

METHODS

In this observational cohort study, we enrolled patients with yellow fever virus from two hospitals in São Paolo-the Hospital das Clínicas, University of São Paulo and the Infectious Diseases Institute "Emilio Ribas". Patients older than 18 years admitted to hospital with fever or myalgia, headache, arthralgia, oedema, rash, or conjunctivitis were consecutively screened for inclusion in the present study. Consenting patients were included if they had travelled to geographical areas in which yellow fever virus cases had been previously confirmed. Yellow fever infection was confirmed by real-time PCR in blood collected at admission or tissues at autopsy. We sequenced the complete genomes of yellow fever virus from infected individuals and evaluated demographic, clinical, and laboratory findings at admission and investigated whether any of these measurements correlated with patient outcome (death).

FINDINGS

Between Jan 11, 2018, and May 10, 2018, 118 patients with suspected yellow fever were admitted to Hospital das Clínicas, and 113 patients with suspected yellow fever were admitted to Infectious Diseases Institute "Emilio Ribas". 95 patients with suspected yellow fever were included in the study, and 136 patients were excluded. Three (3%) of 95 patients with suspected yellow fever who were included in the study were excluded because they received a different diagnosis, and 16 patients with undetectable yellow fever virus RNA were excluded. Therefore, 76 patients with confirmed yellow fever virus infection, based on detectable yellow fever virus RNA in blood (74 patients) or yellow fever virus confirmed only at the autopsy report (two patients), were included in our analysis. 27 (36%) of 76 patients died during the 60 day period after hospital admission. We generated 14 complete yellow fever virus genomes from the first 15 viral load-detectable samples. The genomes belonged to a single monophyletic clade of the South America I genotype, sub-genotype E. Older age, male sex, higher leukocyte and neutrophil counts, higher alanine aminotransferase, aspartate transaminase (AST), bilirubin, and creatinine, prolonged prothrombin time, and higher yellow fever virus RNA plasma viral load were associated with higher mortality. In a multivariate regression model, older age, elevated neutrophil count, increased AST, and higher viral load remained independently associated with death. All 11 (100%) patients with neutrophil counts of 4000 cells per mL or greater and viral loads of 5·1 log₁₀ copies/mL or greater died (95% CI 72-100), compared with only three (11%) of 27 (95% CI 2-29) among patients with neutrophil counts of less than 4000 cells per mL and viral loads of less than 5·1 log₁₀ copies/mL.

INTERPRETATION

We identified clinical and laboratory predictors of mortality at hospital admission that could aid in the care of patients with yellow fever virus. Identification of these prognostic markers in patients could help clinicians prioritise admission to the intensive care unit, as patients often deteriorate rapidly. Moreover, resource allocation could be improved to prioritise key laboratory examinations that might be more useful in determining whether a patient could have a better outcome. Our findings support the important role of the virus in disease pathogenesis, suggesting that an effective antiviral could alter the clinical course for patients with the most severe forms of yellow fever.

FUNDING

São Paulo Research Foundation (FAPESP).

Atovaquone Inhibits Arbovirus Replication through the Depletion of Intracellular Nucleotides

Arthropod-borne viruses represent a significant public health threat worldwide, yet there are few antiviral therapies or prophylaxes targeting these pathogens. In particular, the development of novel antivirals for high-risk populations such as pregnant women is essential to prevent devastating disease such as that which was experienced with the recent outbreak of Zika virus (ZIKV) in the Americas. One potential avenue to identify new and pregnancy-acceptable antiviral compounds is to repurpose well-known and widely used FDA-approved drugs. In this study, we addressed the antiviral role of atovaquone, an FDA Pregnancy Category C drug and pyrimidine biosynthesis inhibitor used for the prevention and treatment of parasitic infections. We found that atovaquone was able to inhibit ZIKV and chikungunya virus virion production in human cells and that this antiviral effect occurred early during infection at the initial steps of viral RNA replication. Moreover, we were able to complement viral replication and virion production with the addition of exogenous pyrimidine nucleosides, indicating that atovaquone functions through the inhibition of the pyrimidine biosynthesis pathway to inhibit viral replication. Finally, using an ex vivo human placental tissue model, we found that atovaquone could limit ZIKV infection in a dose-dependent manner, providing evidence that atovaquone may function as an antiviral in humans. Taken together, these studies suggest that atovaquone could be a broad-spectrum antiviral drug and a potential attractive candidate for the prophylaxis or treatment of arbovirus infection in vulnerable populations, such as pregnant women and children.IMPORTANCE The ability to protect vulnerable populations such as pregnant women and children from Zika virus and other arbovirus infections is essential to preventing the devastating complications induced by these viruses. One class of antiviral therapies may lie in known pregnancy-acceptable drugs that have the potential to mitigate arbovirus infections and disease, yet this has not been explored in detail. In this study, we show that the common antiparasitic drug atovaquone inhibits arbovirus replication through intracellular nucleotide depletion and can impair ZIKV infection in an ex vivo human placental explant model. Our study provides a novel function for atovaquone and highlights that the rediscovery of pregnancy-acceptable drugs with potential antiviral effects can be the key to better addressing the immediate need for treating viral infections and preventing potential birth complications and future disease.

Identifying Protective Health Behaviors on Twitter: Observational Study of Travel Advisories and Zika Virus

BACKGROUND

An estimated 3.9 billion individuals live in a location endemic for common mosquito-borne diseases. The emergence of Zika virus in South America in 2015 marked the largest known Zika outbreak and caused hundreds of thousands of infections. Internet data have shown promise in identifying human behaviors relevant for tracking and understanding other diseases.

OBJECTIVE

Using Twitter posts regarding the 2015-16 Zika virus outbreak, we sought to identify and describe considerations and self-disclosures of a specific behavior change relevant to the spread of disease-travel cancellation. If this type of behavior is identifiable in Twitter, this approach may provide an additional source of data for disease modeling.

METHODS

We combined keyword filtering and machine learning classification to identify first-person reactions to Zika in 29,386 English-language tweets in the context of travel, including considerations and reports of travel cancellation. We further explored demographic, network, and linguistic characteristics of users who change their behavior compared with control groups.

RESULTS

We found differences in the demographics, social networks, and linguistic patterns of 1567 individuals identified as changing or considering changing travel behavior in response to Zika as compared with a control sample of Twitter users. We found significant differences between geographic areas in the United States, significantly more discussion by women than men, and some evidence of differences in levels of exposure to Zika-related information.

CONCLUSIONS

Our findings have implications for informing the ways in which public health organizations communicate with the public on social media, and the findings contribute to our understanding of the ways in which the public perceives and acts on risks of emerging infectious diseases.

Francisco Campos-Rivadeneira and Roberto Levi- Castillo: Their lives and contributions to the study of mosquitoes (Diptera: Culicidae) in Ecuador

The study of mosquitoes is important in the prevention of vector-borne diseases. In Ecuador, the study of local mosquito biodiversity was pioneered by two entomologists whose contributions span through the first half of the 20th century, Francisco Campos-Rivadeneira and Roberto Levi-Castillo. Both of them contributed to general aspects of Entomology and to particular insights in mosquito taxonomy. Their publications and discoveries were recognized by the international scientific community but went unnoticed in South America during their time. Today, very few citizens remember the names and contributions of these two scientists. Here, we provide an overview of their lives, a summary of their contributions, and we conclude with a broader outlook on the practice of science in Latin America during their time.

Epidemiologists of the Future: Data Collectors or Scientists?

Epidemiology is the study of epidemics. It is a biological science that includes expertise in many disciplines in social and behavioral sciences. Epidemiology is also a key component of preventive medicine and public health. Unfortunately, over recent years, academic epidemiology has lost its relationship with preventive medicine, as well as much of its focus on epidemics. The new "-omics" technologies to measure risk factors and phenotypes, and advances in genomics (e.g., host susceptibility) consistent with good epidemiology methods will likely enhance epidemiology research. There is a need based on these new technologies to modify training, especially for the first-level doctorate epidemiologist.

A computational method for the identification of Dengue, Zika and Chikungunya virus species and genotypes

In recent years, an increasing number of outbreaks of Dengue, Chikungunya and Zika viruses have been reported in Asia and the Americas. Monitoring virus genotype diversity is crucial to understand the emergence and spread of outbreaks, both aspects that are vital to develop effective prevention and treatment strategies. Hence, we developed an efficient method to classify virus sequences with respect to their species and sub-species (i.e. serotype and/or genotype). This tool provides an easy-to-use software implementation of this new method and was validated on a large dataset assessing the classification performance with respect to whole-genome sequences and partial-genome sequences. Available online: http://krisp.org.za/tools.php.

Serologic Tools and Strategies to Support Intervention Trials to Combat Zika Virus Infection and Disease

Zika virus is an emerging mosquito-borne flavivirus that recently caused a large epidemic in Latin America characterized by novel disease phenotypes, including Guillain-Barré syndrome, sexual transmission, and congenital anomalies, such as microcephaly. This epidemic, which was declared an international public health emergency by the World Health Organization, has highlighted shortcomings in our current understanding of, and preparation for, emerging infectious diseases in general, as well as challenges that are specific to Zika virus infection. Vaccine development for Zika virus has been a high priority of the public health response, and several candidates have shown promise in pre-clinical and early phase clinical trials. The optimal selection and implementation of imperfect serologic assays are among the crucial issues that must be addressed in order to advance Zika vaccine development. Here, I review key considerations for how best to incorporate into Zika vaccine trials the existing serologic tools, as well as those on the horizon. Beyond that, this discussion is relevant to other intervention strategies to combat Zika and likely other emerging infectious diseases.

Human antibody response to Zika targets type-specific quaternary structure epitopes

The recent Zika virus (ZIKV) epidemic in the Americas has revealed rare but serious manifestations of infection. ZIKV has emerged in regions endemic for dengue virus (DENV), a closely related mosquito-borne flavivirus. Cross-reactive antibodies confound studies of ZIKV epidemiology and pathogenesis. The immune responses to ZIKV may be different in people, depending on their DENV immune status. Here, we focus on the human B cell and antibody response to ZIKV as a primary flavivirus infection to define the properties of neutralizing and protective antibodies generated in the absence of preexisting immunity to DENV. The plasma antibody and memory B cell response is highly ZIKV type-specific, and ZIKV-neutralizing antibodies mainly target quaternary structure epitopes on the viral envelope. To map viral epitopes targeted by protective antibodies, we isolated 2 type-specific monoclonal antibodies (mAbs) from a ZIKV case. Both mAbs were strongly neutralizing in vitro and protective in vivo. The mAbs recognize distinct epitopes centered on domains I and II of the envelope protein. We also demonstrate that the epitopes of these mAbs define antigenic regions commonly targeted by plasma antibodies in individuals from endemic and nonendemic regions who have recovered from ZIKV infections.

[Mosquitoes as vectors of arboviruses: an endless story]

The recent emergence or re-emergence of vector-borne diseases (VBD) and, more specifically, VBD associated with arboviruses such as dengue, chikungunya, Zika or yellow fever are not new events. The globalization of trade and travels as well as the unplanned urbanization of many tropical and subtropical cities have created the conditions suitable for the establishment of vector mosquitoes offering opportunities for arbovirus introduction. This review describes the major arboviruses important for human health and their epidemic vectors, and the conditions leading to their emergence.

Pathogenesis of Non-Zika Congenital Viral Infections

A widespread epidemic of Zika virus (ZIKV) infection was reported in 2015 from South and Central America and the Caribbean. Although the full spectrum of ZIKV infection of the newborn has yet to be determined, other maternal viral infections resulting in transmission to the fetus provide instructive lessons that can be applied to the prospective evaluation of individuals with ZIKV infection. This review focuses on those other congenital infections, including rubella, congenital cytomegalovirus, human immunodeficiency virus, hepatitis B virus, and neonatal herpes simplex virus, from which lessons for the evaluation of ZIKV in the newborn can be applied.

Anti-Zika Activity of a Library of Synthetic Carbohydrate Receptors

Zika virus (ZIKV), a mosquito-borne flavivirus, is a global health concern because of its association with severe neurological disorders. Currently, there are no antiviral therapies that have been specifically approved to treat ZIKV, and there is an urgent need to develop effective anti-ZIKV agents. Here, we report anti-ZIKV activity of 16 synthetic carbohydrate receptors (SCRs) that inhibit ZIKV infection in Vero and HeLa cells. Using a ZIKV reporter virus particle-based infection assay, our data demonstrates these SCRs are highly potent with IC₅₀s as low as 0.16 μM and negligible toxicity at several-fold higher concentrations. Time-of-addition studies showed that these SCRs inhibit the early stages of the virus infection, which is consistent with the proposed mode of action, where the SCRs likely inhibit binding between the virus and cell-surface glycans, thereby preventing viral entry into the cells and, as such, this study demonstrates a potential new strategy against ZIKV.

Intravital imaging of skin infections

Intravital imaging of cutaneous immune responses has revealed intricate links between the skin's structural properties, the immune cells that reside therein, and the carefully orchestrated migratory dynamics that enable rapid sensing and subsequent elimination of skin pathogens. In particular, the development of 2-photon intravital microscopy (2P-IVM), which enables the excitation of fluorescent molecules within deep tissue with minimal light scattering and tissue damage, has proven an invaluable tool in the characterization of different cell subset's roles in skin infection. The ability to visualize cells, tissue structures, pathogens and track migratory dynamics at designated times following infection, or during inflammatory responses has been crucial in defining how immune responses in the skin are coordinated, either locally or in concert with circulating immune cells. Skin pathogens affect millions of people worldwide, and skin infections leading to cutaneous pathology have a considerable impact on the quality of life and longevity of people affected. In contrast, pathogens that infect the skin to later cause systemic illness, such as malaria parasites and a variety of arthropod-borne viruses, or infection in distant anatomical sites are a significant cause of morbidity and mortality worldwide. Here, we review recent advances and seminal studies that employed intravital imaging to characterize key immune response mechanisms in the context of viral, bacterial and parasitic skin infections, and provide insights on skin pathogens of global significance that would benefit from such investigative approaches.

Investigating the probability of establishment of Zika virus and detection through mosquito surveillance under different temperature conditions

Because of the increasing threat that Zika virus (ZIKV) poses to more sub-tropical area due to increased global travel, there is a need for better understanding of the effect(s) of temperature on the establishment potential of ZIKV within these subtropical, temperate, and/or seasonal Ae. aegypti populations. The first step to determining risk establishment of ZIKV in these regions is to assess ZIKV's ability to infect mosquitoes at less tropical temperatures, and thus be detected through common surveillance programs. To that end, the effect of two rearing temperatures (RT) and extrinsic incubation temperatures (EIT) on infection and dissemination rates was evaluated, as well as the interactions of such. Total, there were four combinations (RT24-EIT24, RT24-EIT28, RT28-EIT24, RT28-EIT28). Further, a stochastic SEIR framework was adapted to determine whether observed data could lead to differential success of establishment of ZIKV in naive mosquito populations. There was no consistent pattern in significant differences found across treatments for either infection or dissemination rates (p>0.05), where only a significant difference was found in infection rates between RT24-EIT24 (44%) and RT28-EIT24 (82.6%). Across all temperature conditions, the model predicted between a 76.4% and 95.4% chance of successful establishment of ZIKV in naive mosquito populations under model assumptions. We further show that excluding the maximum observed infection and dissemination rates likely overestimates the probability of local establishment of ZIKV. These results indicate that 1) there is no straightforward relationship between RT, EIT, and infection/dissemination rates, 2) in more temperate climates, ZIKV may still have the ability to establish in populations of Aedes aegypti, 3) despite an overall lack of significant differences in infection/dissemination rates, temperature may still alter the kinetics of ZIKV within the mosquito enough to affect the likelihood of infection establishment and detection within the context of mosquito surveillance programs, and 4) both the temporal and magnitude qualities of vector competence are necessary for parameterization of within-mosquito virus kinetics.

Going Viral 2019: Zika, Chikungunya, and Dengue

Chikungunya and Zika virus infections are emerging diseases in the Americas, and dengue continues to be the most prevalent arthropod-borne virus in the world. These arbovirus diseases may spread by endemic transmission or as travel-related infections and have rapidly expanded their geographic distribution secondary to vector spread. All 3 share a similar clinical picture that includes a maculopapular rash. Zika is characterized by pruritic rash, low-grade fever, and arthralgia. Congenital nervous system malformations are a growing public-health concern. Chikungunya distinctive dermatologic manifestations include facial melanosis and bullous eruption. Dengue bleeding complications may be life-threatening and require inpatient management.

Global expansion and redistribution of Aedes-borne virus transmission risk with climate change

Forecasting the impacts of climate change on Aedes-borne viruses-especially dengue, chikungunya, and Zika-is a key component of public health preparedness. We apply an empirically parameterized model of viral transmission by the vectors Aedes aegypti and Ae. albopictus, as a function of temperature, to predict cumulative monthly global transmission risk in current climates, and compare them with projected risk in 2050 and 2080 based on general circulation models (GCMs). Our results show that if mosquito range shifts track optimal temperature ranges for transmission (21.3-34.0°C for Ae. aegypti; 19.9-29.4°C for Ae. albopictus), we can expect poleward shifts in Aedes-borne virus distributions. However, the differing thermal niches of the two vectors produce different patterns of shifts under climate change. More severe climate change scenarios produce larger population exposures to transmission by Ae. aegypti, but not by Ae. albopictus in the most extreme cases. Climate-driven risk of transmission from both mosquitoes will increase substantially, even in the short term, for most of Europe. In contrast, significant reductions in climate suitability are expected for Ae. albopictus, most noticeably in southeast Asia and west Africa. Within the next century, nearly a billion people are threatened with new exposure to virus transmission by both Aedes spp. in the worst-case scenario. As major net losses in year-round transmission risk are predicted for Ae. albopictus, we project a global shift towards more seasonal risk across regions. Many other complicating factors (like mosquito range limits and viral evolution) exist, but overall our results indicate that while climate change will lead to increased net and new exposures to Aedes-borne viruses, the most extreme increases in Ae. albopictus transmission are predicted to occur at intermediate climate change scenarios.

Green synthesis of silver-nanoparticles from Annona reticulata leaves aqueous extract and its mosquito larvicidal and anti-microbial activity on human pathogens

Silver nanoparticles play a important role in controlling mosquito population as well as multi drug resistant pathogens without causing much harm to humans. In the present study was focused on green synthesis of silver nanoparticles against dengue causing vector (Aedes aegypti) and pathogens affecting humans. The synthesized silver nanoparticle was confirmed using UV- absorption spectrum range obtained at 416 nm, XRD, FTIR and HR-TEM analysis were used to determine the silver nanoparticle morphology and size with ∼6.48 ± 1.2-8.13 ± 0.18 nm and face centered cubic structure. The synthesized silver nanoparticles were exposed to fourth instar larvae of A. aegypti with different concentration (3-20 μg/mL) for 24 h and its elicit maximum mortality (100%) at their final concentration of 20 μg/mL and it's LC50 value was 4.43 μg/mL and LC90 value was 13.96 μg/mL, respectively. The minimum inhibitory activities of the tested pathogens were 125, 31.25, 62.5, 62.6 and 62.5 μg/mL for the Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans respectively. Further, the synthesized silver nanoparticle shows a potent antimicrobial activity against all tested pathogens. Moreover the effect of silver nanoparticle against Red Blood Cells belonging to 'O' positive blood group were tested and does not cause higher hemolysis to the cells even at the highest concentration. Based on these finding, we strongly suggested that face centered cubic structured A. reticulata AgNPs is an eco-friendly and potent bio-medical agent and can be apply in wide range of application an alternative chemically synthesized metal nanoparticle.

Emerging and Reemerging Aedes-Transmitted Arbovirus Infections in the Region of the Americas: Implications for Health Policy

The increasing geographical spread and disease incidence of arboviral infections are among the greatest public health concerns in the Americas. The region has observed an increasing trend in dengue incidence in the last decades, evolving from low to hyperendemicity. Yellow fever incidence has also intensified in this period, expanding from sylvatic-restricted activity to urban outbreaks. Chikungunya started spreading pandemically in 2005 at an unprecedented pace, reaching the Americas in 2013. The following year, Zika also emerged in the region with an explosive outbreak, carrying devastating congenital abnormalities and neurologic disorders and becoming one of the greatest global health crises in years. The inadequate arbovirus surveillance in the region and the lack of serologic tests to differentiate among viruses poses substantial challenges. The evidence for vector control interventions remains weak. Clinical management remains the mainstay of arboviral disease control. Currently, only yellow fever and dengue vaccines are licensed in the Americas, with several candidate vaccines in clinical trials. The Global Arbovirus Group of Experts provides in this article an overview of progress, challenges, and recommendations on arboviral prevention and control for countries of the Americas.

Widespread insecticide resistance in Aedes aegypti L. from New Mexico, U.S.A

BACKGROUND

Aedes aegypti mosquitoes are vectors of a variety of emerging viral pathogens, including yellow fever, dengue, chikungunya, and Zika virus. This species has established endemic populations in all cities across southern New Mexico sampled to date. Presently, control of Aedes-borne viruses relies on deployment of insecticides to suppress mosquito populations, but the evolution of insecticide resistance threatens the success of vector control programs. While insecticide resistance is quite common in Ae. aegypti field populations across much of the U.S., the resistance status of this species in populations from New Mexico has not previously been assessed.

RESULTS

First, we collected information on pesticide use in cities in southern New Mexico and found that the most commonly used active ingredients were pyrethroids. The use of insecticides with the same mode-of-action over multiple years is likely to promote the evolution of resistance. To determine if there was evidence of resistance in some cities in southern New Mexico, we collected Ae. aegypti from the same cities and established laboratory strains to assess resistance to pyrethroid insecticides and, for a subset of populations, to organophosphate insecticides. F2 or F4 generation mosquitoes were assessed for insecticide resistance using bottle test bioassays. The majority of the populations from New Mexico that we analyzed were resistant to the pyrethroids permethrin and deltamethrin. A notable exception to this trend were mosquitoes from Alamogordo, a city that did not report using pyrethroid insecticides for vector control. We screened individuals from each population for known knock down resistance (kdr) mutations via PCR and found a strong association between the presences of the F1534C kdr mutation in the para gene of Ae. aegypti (homologue to F1534C in Musca domestica L.) and pyrethroid resistance.

CONCLUSION

High-level pyrethroid resistance is common in Ae. aegypti from New Mexico and geographic variation in such resistance is likely associated with variation in usage of pyrethroids for vector control. Resistance monitoring and management is recommended in light of the potential for arbovirus outbreaks in this state. Also, alternative approaches to mosquito control that do not involve insecticides should be explored.

Sanitation, Arboviruses, and Environmental Determinants of Disease: impacts on urban health

What are the repercussions of poorly planned urbanization for population health? Understanding urban health, the risks posed by cities, health repercussions, and urban social relations helps urban planners to decide where to target prevention interventions. We conducted a qualitative descriptive analytical study based on a document analysis and bibliographical review to explore the relationship between urbanization and urban health, focusing on diseases transmitted by the mosquito Aedes aegypti. Our findings show that environmental degradation and inadequate infrastructure pose a serious risk to human health, insofar as the disposal of waste in dumps and landfills can cause exposure to hazardous chemicals. In addition, inadequate urban infrastructure and sanitation is conducive to the transmission of water-borne diseases and the reproduction of vectors of other diseases such as Aedes aegypti, responsible for the transmission of arboviruses (dengue, chikungunya, and Zika). Research on environmental and urban health therefore provides an important foundation for improving the quality of life of people living in cities and developing measures designed to prevent diseases related to unplanned urbanization.