Emerging Mosquito-Borne Viruses Linked to Aedes aegypti and Aedes albopictus: Global Status and Preventive Strategies

Emerging mosquito-borne viruses continue to cause serious health problems and economic burden among billions of people living in and near the tropical belt of the world. The highly invasive mosquito species Aedes aegypti and Aedes albopictus have successively invaded and expanded their presence as key vectors of Chikungunya virus, dengue virus, yellow fever virus, and Zika virus, and that has consecutively led to frequent outbreaks of the corresponding viral diseases. Of note, these two mosquito species have gradually adapted to the changing weather and environmental conditions leading to a shift in the epidemiology of the viral diseases, and facilitated their establishment in new ecozones inhabited by immunologically naive human populations. Many abilities of Ae. aegypti and Ae. albopictus, as vectors of significant arbovirus pathogens, may affect the infection and transmission rates after a bloodmeal, and may influence the vector competence for either virus. We highlight that many collaborating risk factors, for example, the global transportation systems may result in sporadic and more local outbreaks caused by mosquito-borne viruses related to Ae. aegypti and/or Ae. albopictus. Those local outbreaks could in synergy grow and produce larger epidemics with pandemic characters. There is an urgent need for improved surveillance of vector populations, human cases, and reliable prediction models. In summary, we recommend new and innovative strategies for the prevention of these types of infections.

The impact of disasters on contraception in OECD member countries: a scoping review

OBJECTIVES

Review evidence is lacking about how contraception is affected by severe social disruption, such as that caused by the COVID-19 pandemic. The purpose of this scoping review was to explore the impact of natural and man-made disasters on contraception in OECD member countries.

METHODS

Manual searches and systematic searches in six electronic databases were conducted with no language restrictions. All articles were screened by at least two researchers. The data were analysed thematically.

RESULTS

108 articles were included. Most focussed on the Zika virus outbreak (n = 50) and the COVID-19 pandemic (n = 28). Four key themes were identified: importance of contraception during disasters, impact of disasters on contraceptive behaviour, barriers to contraception during disasters and ways of improving use of contraception during disasters. Despite efforts to increase access to contraception including by transforming ways of delivery, barriers to use meant that unmet need persisted.

CONCLUSIONS

To prevent adverse health outcomes and reduce health costs as a result of failure to have access to contraception during disasters, there is a need to intensify efforts to remove barriers to use. This should include increasing access and information on methods of contraception and their side effects (e.g., menstrual suppression) and making contraception freely available.

An Innovative United States-Mexico Community Outreach Initiative for Hispanic and Latino People in the United States: A Collaborative Public Health Network

Collaborative partnerships are a useful approach to improve health conditions of disadvantaged populations. The Ventanillas de Salud (VDS) ("Health Windows") and Mobile Health Units (MHUs) are a collaborative initiative of the Mexican government and US public health organizations that use mechanisms such as health fairs and mobile clinics to provide health information, screenings, preventive measures (eg, vaccines), and health services to Mexican people, other Hispanic people, and underserved populations (eg, American Indian/Alaska Native people, geographically isolated people, uninsured people) across the United States. From 2013 through 2019, the VDS served 10.5 million people (an average of 1.5 million people per year) at Mexican consulates in the United States, and MHUs served 115 461 people from 2016 through 2019. We describe 3 community outreach projects and their impact on improving the health of Hispanic people in the United States. The first project is an ongoing collaboration between VDS and the Centers for Disease Control and Prevention (CDC) to address occupational health inequities among Hispanic people. The second project was a collaboration between VDS and CDC to provide Hispanic people with information about Zika virus infection and health education. The third project is a collaboration between MHUs and the University of Arizona to provide basic health services to Hispanic communities in Pima and Maricopa counties, Arizona. The VDS/MHU model uses a collaborative approach that should be further assessed to better understand its impact on both the US-born and non-US-born Hispanic population and the public at large in locations where it is implemented.

Epidemiology of Dengue, Chikungunya, and Zika Virus Disease in U.S. States and Territories, 2017

Dengue, chikungunya, and Zika viruses, primarily transmitted by Aedes species mosquitoes, have caused large outbreaks in the Americas, leading to travel-associated cases and local mosquito-borne transmission in the United States. We describe the epidemiology of dengue, chikungunya, and noncongenital Zika virus disease cases reported from U.S. states and territories in 2017, including 971 dengue cases, 195 chikungunya cases, and 1,118 Zika virus disease cases. Cases of all three diseases reported from the territories were reported as resulting from local mosquito-borne transmission. Cases reported from the states were primarily among travelers, with only seven locally acquired mosquito-transmitted Zika virus disease cases reported from Texas (n = 5) and Florida (n = 2). In the territories, most dengue cases (n = 508, 98%) were reported from American Samoa, whereas the majority of chikungunya (n = 39, 100%) and Zika virus disease (n = 620, 93%) cases were reported from Puerto Rico. Temporally, the highest number of Zika virus disease cases occurred at the beginning of the year, followed by a sharp decline, mirroring decreasing case numbers across the Americas following large outbreaks in 2015 and 2016. Dengue and chikungunya cases followed a more seasonal pattern, with higher case numbers from July through September. Travelers to the United States and residents of areas with active virus transmission should be informed of both the ongoing risk from dengue, chikungunya, and Zika virus disease and personal protective measures to lower their risk of mosquito bites and to help prevent the spread of these diseases.

Evaluation of Patients for Zika Virus Infection in a Travel Clinic in the Southeast United States, 2016

OBJECTIVES

Zika virus is an emerging infection that has posed vexing challenges to the US public health system. Improved characterization of patients with possible and confirmed infection is needed to better understand risks for infection in US travelers and to inform evolving evaluation guidelines.

METHODS

We performed a retrospective electronic health record review of patients evaluated for Zika virus infection at an academic travel clinic in Atlanta, Georgia, from January 1 through August 31, 2016. We evaluated 46 patients who presented to the clinic during this period for evaluation of possible Zika virus infection, including patients with Zika virus symptoms, asymptomatic patients with possible exposure to Zika virus, and referral visits for Zika virus testing.

RESULTS

Among the 46 patients evaluated, 30 (65.2%) were tested for Zika virus, 8 of whom (17.4%) had laboratory evidence of infection (7 confirmed, 1 probable). Cases, including confirmed and probable infections, most commonly had fever, rash, conjunctivitis, headache, and myalgia, although differences compared with noncases were not statistically significant. Many patients evaluated were not tested because of stringent testing criteria.

CONCLUSIONS

Our findings may help inform improvements in timely clinical decision making for Zika virus testing. This may assist clinicians and public health agencies. Wider access to accurate screening modalities will help providers evaluate and advise patients.

Fatal Zika virus infection in the Americas: A systematic review

INTRODUCTION

While death due to Zika virus (ZIKV) infection has been described, reports of fatal cases have been infrequent and no systematic reviews on the subject have been published.

METHODS

A systematic review of the literature in four databases was performed to assess fatal outcomes of postnatal ZIKV infection and the available evidence that links ZIKV infection to death.

RESULTS

Three hundred and eleven articles were retrieved; 20 of them were epidemiological reports from surveillance agencies and ministries of health. After screening by abstract and title, 59 articles were selected for full-text assessment. Of these, 35 were excluded (with reasons) and 24 were finally included for qualitative analysis. A total of 51 reported deaths associated with ZIKV infection in nine countries were identified. The majority of cases (56.9%) were not related to Guillain-Barré syndrome. Cases from three countries accounted for 67.6% of the deaths. ZIKV infection was laboratory-confirmed in the majority of cases (64.7%).

DISCUSSION

ZIKV was not considered to be a dangerous, and much less a lethal pathogen, until very recently. However, an increasing number of fatalities have been published in the literature since the first death was reported in 2016. Additional research is needed to elucidate factors that may mediate the pathogenesis of severe, atypical, and fatal disease.

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.

Ocular Manifestations of Mosquito-Transmitted Diseases

Of the 3,548 known mosquito species, about 100 transmit human diseases. Mosquitoes are distributed globally throughout tropical and temperate regions where standing water sources are available for egg laying and the maturation of larva. Female mosquitoes require blood meals for egg production. This is the main pathway for disease transmission. Mosquitoes carry several pathogenic organisms responsible for significant ocular pathology and vision loss including West Nile, Rift Valley, chikungunya, dengue viruses, various encephalitis viruses, malarial parasites, Francisella tularensis, microfilarial parasites, including Dirofilaria, Wuchereria, and Brugia spp., and human botfly larvae. Health care providers may not be familiar with many of these mosquito-transmitted diseases or their associated ocular findings delaying diagnosis, treatment, and recovery of visual function. This article aims to provide an overview of the ocular manifestations associated with mosquito-transmitted diseases.

Using social media to estimate Zika's impact on tourism: #babymoon, 2014-2017

Zika virus infection during pregnancy can cause microcephaly and other birth defects. We hypothesized that the Latin America Zika epidemic resulted in pregnant women and their partners adopting behavioral changes to limit risk, leading them to forego travel to Zika-affected locations. We evaluated this hypothesis by studying travelers' intent and behavior through Twitter data related to babymoon: a holiday taken by parents-to-be before their baby is born. We found the odds of mentioning representative Zika-affected locations in #babymoon tweets dropped significantly (Odds ratio: 0.29, 95% CI: 0.20-0.40) after the Zika-microcephaly association became well-known. This result was further corroborated through a content analysis of #babymoon tweets mentioning Zika-affected locations, which identified if the Twitter user was physically present in the Zika-affected locations. Conversely, we found a small but statistically insignificant increase in the odds of mentioning Zika-free locations from #babymoon tweets (Odds Ratio: 1.11, 95% CI: 0.97-1.27) after the Zika-microcephaly association became well-known.

Seroprevalence of Dengue and Zika Virus in Blood Donations: A Systematic Review

The presence of antibodies to Zika virus (ZIKV) and dengue virus (DENV) can be detected in blood donations. Donation-based surveillance provides an alternative strategy to estimate population prevalence by detecting antibodies that are circulating. To estimate population prevalence, we conducted a systematic review of literature on the seroprevalence of ZIKV and DENV antibodies in blood donations. We searched PubMed and Web of Science for studies that reported the seroprevalence of ZIKV and DENV in blood donations. The title and abstract of each study were screened by 2 reviewers simultaneously for possible inclusion, and the full text of selected studies was reviewed to ensure that they met inclusion criteria (used primary data collection, reported evidence of immunoglobulin M (IgM) or immunoglobulin G (IgG) antibodies in the blood supply, and included a representative sample of the total population). Immunoglobin test measuring levels of antibodies to IgM and IgG and number of positive cases were extracted from each study. No exclusions were made based on language or country. Our initial search identified 1890 studies after excluding duplicates, of which 76 were assessed for full text eligibility to ensure that they met our final inclusion criteria. There were 14 studies included in our review; 11 examined the seroprevalence of DENV, and 3 examined ZIKV. The highest seroprevalence by IgM was 2.82% for DENV and 0.53% for ZIKV. Our results indicate that the seroprevalence of ZIKV and DENV antibody presence in countries with active transmission is higher than reports by traditional surveillance in some countries. This finding is expected due to the large percentage of asymptomatic cases. The highest seroprevalence was observed for IgG, which can persist over long periods of time compared to IgM. Screening of blood donations may help supplement traditional surveillance measures, especially during outbreak settings.

Quantifying the risk of local Zika virus transmission in the contiguous US during the 2015-2016 ZIKV epidemic

BACKGROUND

Local mosquito-borne Zika virus (ZIKV) transmission has been reported in two counties in the contiguous United States (US), prompting the issuance of travel, prevention, and testing guidance across the contiguous US. Large uncertainty, however, surrounds the quantification of the actual risk of ZIKV introduction and autochthonous transmission across different areas of the US.

METHODS

We present a framework for the projection of ZIKV autochthonous transmission in the contiguous US during the 2015-2016 epidemic using a data-driven stochastic and spatial epidemic model accounting for seasonal, environmental, and detailed population data. The model generates an ensemble of travel-related case counts and simulates their potential to have triggered local transmission at the individual level in the 2015-2016 ZIKV epidemic.

RESULTS

We estimate the risk of ZIKV introduction and local transmission at the county level and at the 0.025° × 0.025° cell level across the contiguous US. We provide a risk measure based on the probability of observing local transmission in a specific location during a ZIKV epidemic modeled after the epidemic observed during the years 2015-2016. The high spatial and temporal resolution of the model allows us to generate statistical estimates of the number of ZIKV introductions leading to local transmission in each location. We find that the risk was spatially heterogeneously distributed and concentrated in a few specific areas that account for less than 1% of the contiguous US population. Locations in Texas and Florida that have actually experienced local ZIKV transmission were among the places at highest risk according to our results. We also provide an analysis of the key determinants for local transmission and identify the key introduction routes and their contributions to ZIKV transmission in the contiguous US.

CONCLUSIONS

This framework provides quantitative risk estimates, fully captures the stochasticity of ZIKV introduction events, and is not biased by the under-ascertainment of cases due to asymptomatic cases. It provides general information on key risk determinants and data with potential uses in defining public health recommendations and guidance about ZIKV risk in the US.

Zika virus: - a review of the main aspects of this type of arbovirosis

The objective of this study was to integrate findings related to Zika virus from the scientific literature. An integrative review of Medline was conducted, and data search was performed using the Health Sciences Descriptor Zika virus and the following filters: full texts available; studies in humans; full articles; and publications in Portuguese, French, English, and Spanish. After application of the filters, followed by reading of the titles, abstracts, and full texts, 44 studies were included in the review, for which content analysis was performed. A large part of the literature comprised review articles (84%; N=37); the majority was in English (95%, N=42). In 2016, 84% (N=37) of our sample articles was published, while in 2017, 16% (N=7) was published. The main form of viral transmission was thorough the mosquito Aedes aegypti (N=30). In addition, sexual transmission (N=09), transmission through blood transfusion (N=16), vertical transmission (N=21) and transmission from occupational activities (N=03) occurred. It was possible to diagnose the disease by testing blood (N=22), urine (N=14), saliva (N=06), semen/sperm (N=03), cerebrospinal and amniotic fluid, and other tissues (N=02). Symptomatology occurred in 1-5 people (N=10) between 3 and 7 days after a mosquito bite (N=09). Complications observed were Guillain Barré syndrome (N=27); neurological Zika syndrome (N=27); meningitis, meningoencephalitis, and myelitis (N=07); deaths and/or newborns (N=03). The review provides scientific evidence that contributes to the care, planning and implementation of public policies.

Demographic and Travel Characteristics of Travel-Associated Zika Virus Infection Case-Patients in San Diego County, California (January 1, 2016-March 31, 2017)

Most Zika disease cases diagnosed in the continental US have been associated with travel to areas with risk of Zika transmission, mainly the Caribbean and Latin America. Limited information has been published about the demographic and travel characteristics of Zika case-patients in the United States, besides their age and gender. During 2016-2017 the County of San Diego Health and Human Services Agency, California, expanded the scope and completeness of demographic and travel information collected from Zika case-patients for public health surveillance purposes. The majority (53.8%) of travel-related Zika virus infection case-patients (n = 78) in the county were Hispanic, significantly higher (p ≤ 0.05) than the 33.0% of Hispanics in the county. Foreign-born residents, mainly from Mexico, were also overrepresented among cases compared to their share in the county population (33.3 vs. 23.0%; p ≤ 0.05). Seventeen (21.8%) patients reported a primary language other than English (14 Spanish). Most case-patients traveled for tourism (54%) or to visit friends and relatives (36%). This surveillance information helps identify higher-risk populations and implement culturally targeted interventions for Zika prevention and control.

Diagnostic Testing for Zika Virus: a Postoutbreak Update

Since the emergence and dissemination of Zika virus (ZIKV) in late 2015, our understanding of the biology, transmission, clinical disease, and potential sequelae associated with infection has markedly expanded. Over the past 2 years, the number of diagnostic assays for ZIKV has increased from none in 2015 to 5 serological assays and 14 molecular assays in 2017, all with emergency use authorization granted through the U.S. Food and Drug Administration. Here we provide an update on ZIKV, addressing what we have collectively learned since the outbreak began, including a summary of currently available diagnostic assays for this virus.

Zika Virus Awareness and Prevention Practices Among University Students in Miami: Fall 2016

In January 2016, the first case of mosquito-borne Zika infection in the mainland United States was confirmed in Miami, Florida. The first locally acquired case was reported 6 months later. Local public health and school officials began warning students of the outbreak on their return to the classroom in August 2016. In November–December 2016, we conducted a survey of students attending a large public university in Miami to determine how well informed they were about Zika. A multistage sampling design was used to contact teaching assistants and ask them for help in recruiting their students. Eligible students had to be 18 years of age or older and enrolled in at least one three-credit course during fall semester. A 25-item questionnaire based on the World Health Organization Zika Knowledge, Attitudes, and Practice Resource Pack was developed, pretested, and approved by the university’s institutional review board before it was made available to eligible students through Blackboard Learn or a survey link. About half (50.4%) of the 139 respondents had heard about Zika prior to 2016. Only one student was unaware of Zika before our survey. Most (47.1%) first learned about Zika through television, 18.8% from family or friends, and 15.2% from the Internet, social media, or university e-mail. Two thirds (66.2%) believed Zika could be prevented, 15.1% thought it might be prevented, and 85.7% had taken some precautions. A high level of awareness of the risk of Zika infection was apparent. Most students reported taking steps to avoid exposure to the Zika virus.

Zika virus infection as a cause of congenital brain abnormalities and Guillain-Barré syndrome: From systematic review to living systematic review

Background. The Zika virus (ZIKV) outbreak in the Americas has caused international concern due to neurological sequelae linked to the infection, such as microcephaly and Guillain-Barré syndrome (GBS). The World Health Organization stated that there is “sufficient evidence to conclude that Zika virus is a cause of congenital abnormalities and is a trigger of GBS”. This conclusion was based on a systematic review of the evidence published until 30.05.2016. Since then, the body of evidence has grown substantially, leading to this update of that systematic review with new evidence published from 30.05.2016 – 18.01.2017, update 1.

Methods. We review evidence on the causal link between ZIKV infection and adverse congenital outcomes and the causal link between ZIKV infection and GBS or immune-mediated thrombocytopaenia purpura. We also describe the transition of the review into a living systematic review, a review that is continually updated.

Results. Between 30.05.2016 and 18.01.2017, we identified 2413 publications, of which 101 publications were included. The evidence added in this update confirms the conclusion of a causal association between ZIKV and adverse congenital outcomes. New findings expand the evidence base in the dimensions of biological plausibility, strength of association, animal experiments and specificity. For GBS, the body of evidence has grown during the search period for update 1, but only for dimensions that were already populated in the previous version. There is still a limited understanding of the biological pathways that potentially cause the occurrence of autoimmune disease following ZIKV infection.

Conclusions. This systematic review confirms previous conclusions that ZIKV is a cause of congenital abnormalities, including microcephaly, and is a trigger of GBS. The transition to living systematic review techniques and methodology provides a proof of concept for the use of these methods to synthesise evidence about an emerging pathogen such as ZIKV.

Zika clinical updates: implications for pediatrics

PURPOSE OF REVIEW

Zika virus (ZIKV), a mosquito-borne flavivirus, has gained recognition over the past few years as an important new cause of congenital infection. As a result, it is critical that pediatricians understand its epidemiology, clinical presentation, clinical sequelae, and management.

RECENT FINDINGS

The recent ZIKV epidemiology, clinical presentation of acute infection in children and complications, perinatal infection, and congenital infection will be summarized in this ZIKV review. This will be followed by a brief summary on ZIKV diagnosis, management, treatment, and prevention.

SUMMARY

The field of clinical research in ZIKV has rapidly evolved over recent months. It is critical that pediatricians continue to stay up-to-date with the continuously evolving understanding of the clinical aspects of ZIKV to ensure optimal identification and management of affected infants and children. Given the recent changes in Centers for Disease Control and Prevention guidelines to limit screening of asymptomatic pregnant women in the United States with possible ZIKV exposure, comprehensive ZIKV clinical knowledge becomes even more crucial.

Zika virus dynamics in body fluids and risk of sexual transmission in a non-endemic area

OBJECTIVE

To understand Zika virus (ZIKV) dynamics in fluids of infected individuals and the risk of sexual transmission.

METHODS

Prospective study at two centres in Spain. Patients with probable or confirmed diagnosis of ZIKV infection were clinically followed up, and fluid samples were collected from saliva, serum, urine and semen or vaginal secretion following the study protocol. Non-traveller-sexual partners were offered to participate.

RESULTS

From January 2016 to December 2016, we included a total of 11 traveller patients and six sexual contacts. Six patients were male, with a median age of 38 years (IQR 30-45). We performed 61 RT-PCR determinations, seven of which were positive. Positive results were retrieved from serum, urine, semen and vaginal tract. One of four women tested positive for ZIKV RNA in vaginal swabs collected during the first 45 days after symptoms onset. Clearance occurred between day 37 and day 69 after symptoms onset. One of five men tested positive for ZIKV RNA in semen collected during the first 45 days after symptoms onset. Clearance occurred between day 23 and 107 after symptoms onset. Six patients had sexual relations during the defined period. All tested patients were negative for ZIKV infection by serological testing.

CONCLUSION

ZIKV shedding persistence in genital fluids occurs in a significant number of symptomatic patients after visiting an endemic area. We did not find any ZIKV seroconversion among the three male contacts who were investigated. Diagnostic algorithms may be updated to include genital tract fluid specimens in the diagnostic process.

Quantifying Zika: Advancing the Epidemiology of Zika With Quantitative Models

When Zika virus (ZIKV) emerged in the Americas, little was known about its biology, pathogenesis, and transmission potential, and the scope of the epidemic was largely hidden, owing to generally mild infections and no established surveillance systems. Surges in congenital defects and Guillain-Barré syndrome alerted the world to the danger of ZIKV. In the context of limited data, quantitative models were critical in reducing uncertainties and guiding the global ZIKV response. Here, we review some of the models used to assess the risk of ZIKV-associated severe outcomes, the potential speed and size of ZIKV epidemics, and the geographic distribution of ZIKV risk. These models provide important insights and highlight significant unresolved questions related to ZIKV and other emerging pathogens.

Understanding the Pathogenesis of Zika Virus Infection Using Animal Models

Zika virus (ZIKV) is a member of Flaviviridae family that has emerged as a pathogen of significant public health importance. The rapid expansion of ZIKV in the South and Central America has recently gained medical attention emphasizing the capacity of ZIKV to spread to non-endemic regions. ZIKV infection during pregnancy has been demonstrated to cause microcephaly and other fetal developmental abnormalities. An increased incidence of Guillain-Barre syndrome, an immune mediated neuropathy of the peripheral nervous system, has also been reported in ZIKV-infected patients in French Polynesia and Brazil. No effective therapies currently exist for treating patients infected with ZIKV. Despite the relatively short time interval, an intensive effort by the global scientific community has resulted in development of animal models to study multiple aspects of ZIKV biology. Several animal models have been established to investigate pathogenesis of ZIKV in adults, pregnant mothers, and developing fetuses. Here we review the remarkable progress of newly developed small and large animal models for understanding ZIKV pathogenesis.

Impact of Zika virus for infertility specialists: current literature, guidelines, and resources

In the past 2 years, Zika virus has emerged from obscurity onto the world stage-traversing and transcending clinical specialties, basic science disciplines, and public health efforts. The spread of Zika virus has serious implications for the specialty of reproductive endocrinology and infertility. Our patients, practices, and labs-worldwide and specifically in the USA-have been impacted by this teratogenic, sexually transmitted, largely asymptomatic virus. While the World Health Organization's Public Emergency of International Concern designation has lapsed as major epidemics have subsided and understanding of risks is in part clarified, the acute and long-term threat to pregnant patients is not over. The risk of wider spread in the USA is not insignificant, the subtler and long-ranging consequences beyond microcephaly are not fully known, large geographic areas of risk still contain naïve populations, and whether Zika will continue to be an intermittent risk in endemic areas is uncertain. Staying up to date with the burgeoning research on Zika virus is an important objective for the infertility specialist. Here, we review in detail the most relevant recent developments, discuss applicable guidelines, and propose strategies for contributing to a reduction in the risk and burden of Zika virus.

Asymptomatic Transmission and the Dynamics of Zika Infection

Following the 2013-14 outbreak in French Polynesia, the Zika virus (ZIKV) epidemic spread widely to many countries where Aedes Aegypti as the main transmitting vector is endemic. The lack of a second wave of ZIKV infection in most affected regions may suggest that a sufficiently high level of herd immunity was reached during the first wave. We developed an agent-based transmission model to investigate the role of asymptomatic infection on the likelihood of observing a second wave, while accounting for its relative transmissibility. We found that, as the relative transmissibility of asymptomatic infection increases, a second wave is more likely to occur, despite an increase in the attack rate during the first wave. When the reproduction number varies between 1.9 and 2.8 based on estimates for Antioquia, Colombia, the attack rate varies between 4% and 26% for a low (below 10%) effectiveness of interventions in blunting the ZIKV transmission from symptomatic cases to mosquitoes. Moreover, the fraction of cases due to sexual transmission is estimated below 4% of the cumulative incidence. Our analyses underscore the need to quantify the transmissibility of asymptomatic infections, without which the overall attack rates and the level of herd immunity cannot be accurately estimated.

Zika Virus and Patient Blood Management

Sporadic Zika virus infections had only occurred in Africa and Asia until an outbreak in Micronesia (Oceania) in 2007. In 2013 to 2014, several outer Pacific Islands reported local outbreaks. Soon thereafter, the virus was likely introduced in Brazil from competing athletes from French Polynesia and other countries that participated in a competition there. Transmission is thought to have occurred through mosquito bites and spread to the immunologically naive population. Being also a flavivirus, the Zika virus is transmitted by the Aedes mosquito that is endemic in South and Central America that is also the vector of West Nile virus, dengue, and chikungunya. In less than a year, physicians in Brazil reported a many-fold increase in the number of babies born with microcephaly. Despite initial skepticism regarding the causal association of the Zika virus epidemic and birth defects, extensive basic and clinical research evidence has now confirmed this relationship. In the United States, more than 4000 travel-associated infections have been reported by the middle of 2016 to the Centers for Disease Control and Prevention. Furthermore, many local mosquito-borne infections have occurred in Puerto Rico and Florida. Considering that the virus causes a viremia in which 80% of infected individuals have no symptoms, the potential for transfusion transmission from an asymptomatic blood donor is high if utilizing donor screening alone without testing. Platelet units have been shown to infect 2 patients via transfusion in Brazil. Although there was an investigational nucleic acid test available for testing donors, not all blood centers were initially required to participate. Subsequently, the US Food and Drug Administration issued a guidance in August 2016 that recommended universal nucleic acid testing for the Zika virus on blood donors.In this report, we review the potentially devastating effects of Zika virus infection during pregnancy and its implication in cases of Guillain-Barre syndrome in adults. Furthermore, we urge hospital-based clinicians and transfusion medicine specialists to implement perisurgical patient blood management strategies to avoid blood component transfusions with their potential risks of emerging pathogens, illustrated here by the Zika virus. Ultimately, this current global threat, as described by the World Health Organization, will inevitably be followed by future outbreaks of other bloodborne pathogens; the principles and practices of perioperative patient blood management will reduce the risks from not only known, but also unknown risks of blood transfusion for our patients.

Knowledge and Prevention Practices among U.S. Pregnant Immigrants from Zika Virus Outbreak Areas

We administered an anonymous survey to assess knowledge, attitudes, and prevention practices related to the Zika virus among pregnant women residing in Texas. Multivariate logistic regression models controlling for age, race/ethnicity, education, and number of years in the United States assessed differences between women born in outbreak areas (N = 390) versus those born in the United States (N = 249). Results demonstrated that most women wanted more information on the Zika virus and desired to obtain it from their physician. The majority did not know that the Zika virus could be spread through sex with an asymptomatic partner or how often those infected were symptomatic. Few women took precautions to avoid mosquito bites. Only 40% reported frequently using repellent; 21% stated that cost was problematic and almost half were concerned about use during pregnancy. Three-fourths stated they would agree to vaccination, if available. Compared with U.S.-born women, those born in outbreak areas were more likely to have already discussed the Zika virus with their doctor (adjusted odds ratio [aOR] = 1.86, 95% confidence interval [CI] = 1.27, 2.71) and identify microcephaly as the most common birth defect (aOR = 2.59, 95% CI = 1.78, 3.76). Moreover, women born in outbreak areas were less likely to desire to keep it a secret if they became infected (aOR = 0.47, 95% CI = 0.31, 0.71). This study found that, regardless of birthplace, pregnant women need more education on the Zika virus disease and assurance regarding the safety of using repellent during pregnancy. They also need financial assistance for repellent, especially if living in states where transmission by mosquitos has been reported.

A guinea pig model of Zika virus infection

BACKGROUND

Animal models are critical to understand disease and to develop countermeasures for the ongoing epidemic of Zika virus (ZIKV). Here we report that immunocompetent guinea pigs are susceptible to infection by a contemporary American strain of ZIKV.

METHODS

Dunkin-Hartley guinea pigs were inoculated with 10⁶ plaque-forming units of ZIKV via subcutaneous route and clinical signs were observed. Viremia, viral load in the tissues, anti-ZIKV neutralizing antibody titer, and protein levels of multiple cytokine and chemokines were analyzed using qRT-PCR, plaque assay, plaque reduction neutralization test (PRNT) and multiplex immunoassay.

RESULTS

Upon subcutaneous inoculation with PRVABC59 strain of ZIKV, guinea pigs demonstrated clinical signs of infection characterized by fever, lethargy, hunched back, ruffled fur, and decrease in mobility. ZIKV was detected in the whole blood and serum using qRT-PCR and plaque assay. Anti-ZIKV neutralizing antibody was detected in the infected animals using PRNT. ZIKV infection resulted in a dramatic increase in protein levels of multiple cytokines, chemokines and growth factors in the serum. ZIKV replication was observed in spleen and brain, with the highest viral load in the brain. This data demonstrate that after subcutaneous inoculation, the contemporary ZIKV strain is neurotropic in guinea pigs.

CONCLUSION

The guinea pig model described here recapitulates various clinical features and viral kinetics observed in ZIKV-infected patients, and therefore may serve as a model to study ZIKV pathogenesis, including pregnancy outcomes and for evaluation of vaccines and therapeutics.

Seven Cases of Zika Virus Infection in South Florida

INTRODUCTION

Zika virus, an arbovirus of the Flaviviridae family, is a mosquito-borne virus known to cause microcephaly through vertical transmission. Infection presents with mild, self-limiting symptoms. Currently, a Zika virus outbreak has spread across most of South and Central America. Travel-related and sexually transmitted cases have been reported across the United States. However, the vector-borne transmission has been limited to Florida and Texas. We present seven cases of Zika virus infection that presented at a single institution in South Florida.

METHODS

Patients were included that had real-time polymerase-chain reaction (RT-PCR) for Zika virus RNA in urine or serum or enzyme-linked immunosorbent assay (ELISA) for Immunoglobulin M (IgM) antibody against Zika virus in serum.

RESULTS

All seven patients reported recent travel or employment in areas of active Zika virus transmission and at least two of the four most commonly reported symptoms (fever, arthralgia, rash, and conjunctivitis) with a rash present in all patients. All patients had positive RT-PCR for Zika virus RNA in urine. RT-PCR for Zika virus RNA in serum was negative in four of five patients that were tested, indicating that these patients likely presented one to two weeks after symptom onset.

CONCLUSION

The future of Zika virus outbreaks in other cities in the United States is still uncertain. However, it is clear that prevention and control policies are urgently needed. We have presented seven confirmed cases of Zika virus infection in South Florida. In addition to conducting research concerning both the diagnostic and therapeutic aspects of the virus, there is a need for public awareness of its presentation, methods of transmission, and subsequent clinical outcomes.

Infant outcomes among women with Zika virus infection during pregnancy: results of a large prenatal Zika screening program

BACKGROUND

Zika virus infection during pregnancy is a known cause of congenital microcephaly and other neurologic morbidities.

OBJECTIVE

We present the results of a large-scale prenatal screening program in place at a single-center health care system since March 14, 2016. Our aims were to report the baseline prevalence of travel-associated Zika infection in our pregnant population, determine travel characteristics of women with evidence of Zika infection, and evaluate maternal and neonatal outcomes compared to women without evidence of Zika infection.

STUDY DESIGN

This is a prospective, observational study of prenatal Zika virus screening in our health care system. We screened all pregnant women for recent travel to a Zika-affected area, and the serum was tested for those considered at risk for infection. We compared maternal demographic and travel characteristics and perinatal outcomes among women with positive and negative Zika virus tests during pregnancy. Comprehensive neurologic evaluation was performed on all infants delivered of women with evidence of possible Zika virus infection during pregnancy. Head circumference percentiles by gestational age were compared for infants delivered of women with positive and negative Zika virus test results.

RESULTS

From March 14 through Oct. 1, 2016, a total of 14,161 pregnant women were screened for travel to a Zika-affected country. A total of 610 (4.3%) women reported travel, and test results were available in 547. Of these, evidence of possible Zika virus infection was found in 29 (5.3%). In our population, the prevalence of asymptomatic or symptomatic Zika virus infection among pregnant women was 2/1000. Women with evidence of Zika virus infection were more likely to have traveled from Central or South America (97% vs 12%, P < .001). There were 391 deliveries available for analysis. There was no significant difference in obstetric or neonatal morbidities among women with or without evidence of possible Zika virus infection. Additionally, there was no difference in mean head circumference of infants born to women with positive vs negative Zika virus testing. No microcephalic infants born to women with Zika infection were identified, although 1 infant with hydranencephaly was born to a woman with unconfirmed possible Zika disease. Long-term outcomes for infants exposed to maternal Zika infection during pregnancy are yet unknown.

CONCLUSION

Based on a large-scale prenatal Zika screening program in an area with a predominantly Hispanic population, we identified that 4% were at risk from reported travel with only 2/1000 infected. Women traveling from heavily affected areas were most at risk for infection. Neonatal head circumference percentiles among infants born to women with evidence of possible Zika virus infection during pregnancy were not reduced when compared to infants born to women without infection.

Zika Virus Methyltransferase: Structure and Functions for Drug Design Perspectives

The Flavivirus Zika virus (ZIKV) is the causal agent of neurological disorders like microcephaly in newborns or Guillain-Barre syndrome. Its NS5 protein embeds a methyltransferase (MTase) domain involved in the formation of the viral mRNA cap. We investigated the structural and functional properties of the ZIKV MTase. We show that the ZIKV MTase can methylate RNA cap structures at the N-7 position of the cap, and at the 2'-O position on the ribose of the first nucleotide, yielding a cap-1 structure. In addition, the ZIKV MTase methylates the ribose 2'-O position of internal adenosines of RNA substrates. The crystal structure of the ZIKV MTase determined at a 2.01-Å resolution reveals a crystallographic homodimer. One chain is bound to the methyl donor (S-adenosyl-l-methionine [SAM]) and shows a high structural similarity to the dengue virus (DENV) MTase. The second chain lacks SAM and displays conformational changes in the αX α-helix contributing to the SAM and RNA binding. These conformational modifications reveal a possible molecular mechanism of the enzymatic turnover involving a conserved Ser/Arg motif. In the second chain, the SAM binding site accommodates a sulfate close to a glycerol that could serve as a basis for structure-based drug design. In addition, compounds known to inhibit the DENV MTase show similar inhibition potency on the ZIKV MTase. Altogether these results contribute to a better understanding of the ZIKV MTase, a central player in viral replication and host innate immune response, and lay the basis for the development of potential antiviral drugs.IMPORTANCE The Zika virus (ZIKV) is associated with microcephaly in newborns, and other neurological disorders such as Guillain-Barre syndrome. It is urgent to develop antiviral strategies inhibiting the viral replication. The ZIKV NS5 embeds a methyltransferase involved in the viral mRNA capping process, which is essential for viral replication and control of virus detection by innate immune mechanisms. We demonstrate that the ZIKV methyltransferase methylates the mRNA cap and adenosines located in RNA sequences. The structure of ZIKV methyltransferase shows high structural similarities to the dengue virus methyltransferase, but conformational specificities highlight the role of a conserved Ser/Arg motif, which participates in RNA and SAM recognition during the reaction turnover. In addition, the SAM binding site accommodates a sulfate and a glycerol, offering structural information to initiate structure-based drug design. Altogether, these results contribute to a better understanding of the Flavivirus methyltransferases, which are central players in the virus replication.

Zika virus knowledge, attitudes, and vaccine interest among university students

BACKGROUND

Zika virus vaccine development is underway. We examined interest in receiving a Zika virus vaccine (after one becomes commercially available) among students at a large public university in Northern Virginia.

METHODS

An online survey of Zika virus-related knowledge, attitudes, and interest in receiving a Zika vaccine was completed by 619 undergraduate students in April, 2016. Stepwise logistic regression with backward elimination was used to identify the variables most strongly associated with interest in being vaccinated against Zika virus.

RESULTS

More than half of participants (52.8%) reported that they would be likely or very likely to be vaccinated against Zika virus. Vaccination interest was significantly higher among participants who received an influenza vaccine in the past year (p=0.002), had higher levels of knowledge about Zika virus (p=0.046), reported knowing where to access information about Zika virus (p=0.041), had higher perceived susceptibility to Zika virus (p<0.001), and believed that the U.S. Government should prioritize actions to control Zika virus (p=0.001).

CONCLUSIONS

Communication and intervention strategies encouraging vaccine uptake may benefit from increasing knowledge of Zika virus, addressing perceived susceptibility, and reaching students, travelers, and others who may be seeking information about prevention of Zika virus and other emerging infectious diseases.

Prevalence of Antibodies to Zika Virus in Mothers from Hawaii Who Delivered Babies with and without Microcephaly between 2009-2012

Zika virus (ZIKV) is an emerging mosquito-borne pathogen. ZIKV infection is linked to the development of severe fetal abnormalities that include spontaneous abortion, stillbirth, hydranencephaly, and microcephaly. ZIKV outbreaks have been recorded in the United States. We recently demonstrated the first congenital ZIKV infection in the United States. In this study, we investigated archived blood samples from six mothers who gave birth to babies with microcephaly and 12 mothers who gave birth to healthy babies in Hawaii between 2009 and 2012. We tested maternal blood for the presence of ZIKV IgM and IgG antibodies using commercially available human ZIKV IgM and IgG ELISA kits. Blood from one mother who delivered babies with microcephaly tested positive for ZIKV IgM antibody (16.6%) and blood from three mothers tested positive for ZIKV IgG antibody (50%). ZIKV showed a trend toward significance with microcephaly. ZIKV IgG antibody positive mothers were more likely to deliver babies with microcephaly than mothers who were negative for ZIKV IgG antibodies (Odds ratio [OR] = 11.0, 95% confidence interval [CI] = 0.8–147.9, p = 0.083). Similarly, ZIKV IgM antibody positive mothers were also more likely to deliver babies with microcephaly than mothers who were negative for ZIKV IgM antibody (OR = 6.8, 95% CI = 0.2–195.1). These data provide further evidence of a link between ZIKV infection and microcephaly and suggests presence of ZIKV positive cases and associated microcephaly in the United States as early as 2009.

Zika virus (ZIKV) infection is linked to the development of severe fetal abnormalities that include spontaneous abortion, stillbirth, hydranencephaly, and microcephaly. The WHO in early February 2016 declared global ZIKV outbreaks and its link to birth defects an international public health emergency. ZIKV outbreaks have been recorded in the United States. In a quest to find a link between ZIKV infection and babies born with microcephaly in Hawaii, we investigated archived blood samples from mothers who gave birth in Hawaii between 2009 and 2012 to babies with microcephaly. ZIKV antibodies were detected in three (50%) out of total six mothers who delivered babies with microcephaly. ZIKV showed a trend toward significance with microcephaly. This report adds to the potential evidence of a link between ZIKV infection and microcephaly and suggests presence of ZIKV positive cases and associated microcephaly in the United States as early as 2009.

How Relevant Is Sexual Transmission of Zika Virus?

Christian Althaus and Nicola Low reflect on the contribution of sexual transmission to the spread of Zika virus.