Update: Interim Guidance for Preconception Counseling and Prevention of Sexual Transmission of Zika Virus for Persons with Possible Zika Virus Exposure - United States, September 2016

Molecular surveillance of arboviruses in Nigeria

Arboviral infections are fast becoming a global public health concern as a result of its high fatality rate and sporadic spread. From the outbreak of Zika virus in the Americas, the endemicity of Yellow fever in West Africa and South America, outbreaks of West Nile virus in South Africa to the year-round and national risk of Dengue fever in Mainland China and India. The war against emerging and re-emerging viral infection could probably lead to the next pandemic. To be above the pending possible arboviral pandemic, consistent surveillance of these pathogens is necessary in every society. This study was aimed at conducting a surveillance for Yellow fever virus, Zika virus, Chikungunya virus, Dengue virus and Rift Valley fever virus in four states in Nigeria using molecular techniques. A cross-sectional study involving 1600 blood samples collected from febrile patients in Lagos, Kwara, Ondo and Delta States between 2018 and 2021 was conducted using Real time polymerase chain reaction for detection of the pathogens. Extraction and purification of viral RNA were done using Qiagen Viral RNA Mini Kit. Samples were analyzed using One Step PrimeScript III RT-PCR mix (Takara Bio) alongside optimized primers and probes designed in-house. Positive samples were sequenced on MinION platform (Nanopore technologies). Bioinformatic and phylogenetic analysis were performed with DNASTAR Lasergene 17.3. All the RNA extracted from samples collected from the four states were negative for ZIKV RNA, RVFV RNA, CHIKV RNA and DENV RNA. However, twelve of the samples (2%) tested positive for YFV RNA. Three full genomes of sizes 10,751 bp, 10,500 bp and 10,715 bp were generated and deposited in GenBank with accession numbers: ON323052, ON323053 and ON323054 respectively. Phylogenetic analysis shows clustering within lineage 3 of West African genotype. This result shows an active spread of Yellow fever in Delta State, Nigeria. However, there is no emergence of a new genotype There is a need for an intense surveillance of Yellow fever virus in Nigeria to avert a major outbreak.

Arthropod-Borne Flaviviruses in Pregnancy

Flaviviruses are a diverse group of enveloped RNA viruses that cause significant clinical manifestations in the pregnancy and postpartum periods. This review highlights the epidemiology, pathophysiology, clinical features, diagnosis, and prevention of the key arthropod-borne flaviviruses of concern in pregnancy and the neonatal period-Zika, Dengue, Japanese encephalitis, West Nile, and Yellow fever viruses. Increased disease severity during pregnancy, risk of congenital malformations, and manifestations of postnatal infection vary widely amongst this virus family and may be quite marked. Laboratory confirmation of infection is complex, especially due to the reliance on serology for which flavivirus cross-reactivity challenges diagnostic specificity. As such, a thorough clinical history including relevant geographic exposures and prior vaccinations is paramount for accurate diagnosis. Novel vaccines are eagerly anticipated to ameliorate the impact of these flaviviruses, particularly neuroinvasive disease manifestations and congenital infection, with consideration of vaccine safety in pregnant women and children pivotal. Moving forward, the geographical spread of flaviviruses, as for other zoonoses, will be heavily influenced by climate change due to the potential expansion of vector and reservoir host habitats. Ongoing 'One Health' engagement across the human-animal-environment interface is critical to detect and responding to emergent flavivirus epidemics.

Condom use among women of reproductive age (18-49 years) in Puerto Rico during the 2016 Zika virus outbreak: secondary analysis of data from a cross-sectional, population-based, cell-phone survey

OBJECTIVES

Zika virus (ZIKV) can be sexually transmitted, and ZIKV infection during pregnancy can cause birth defects. Contraception is a medical countermeasure to reduce unintended pregnancy and ZIKV-associated birth defects. We estimated the prevalence of condom use and associated factors among women at risk for unintended pregnancy in Puerto Rico during the 2016 ZIKV outbreak.

DESIGN

Secondary analysis of a cross-sectional, population-based, cell-phone survey.

SETTING AND PARTICIPANTS

Women, 18-49 years, living in Puerto Rico during July-November 2016. We limited our analytical sample (n=1840) to women at risk for unintended pregnancy, defined as those who were sexually active with a man in the last 3 months and did not report menopause, hysterectomy, current pregnancy or desiring pregnancy.

OUTCOME MEASURES

We estimated the weighted prevalence of any condom use among women at risk for unintended pregnancy. We calculated crude and adjusted prevalence ratios (aPRs) to examine the association between condom use and ZIKV-related factors, stratified by use of more effective versus less effective or no contraception.

RESULTS

Overall, 32.7% (95% CI: 30.2% to 35.1%) of women reported any condom use in the last 3 months. Among women using more effective contraception, condom use was higher for women who received ZIKV counselling (aPR: 1.61, 95% CI: 1.15 to 2.25) and those worried about having a child with a ZIKV-associated birth defect (aPR: 1.47, 95% CI: 1.03 to 2.10). Among women using less effective or no contraception, condom use was associated with being worried (aPR: 1.20, 95% CI: 1.01 to 1.43) compared with those not worried about ZIKV infection or with a previous known infection.

CONCLUSIONS

During the 2016 ZIKV outbreak, one in three women at risk for unintended pregnancy reported any condom use. Counselling to promote consistent and correct condom use may address concerns regarding ZIKV among women of reproductive age, which may differ by use of effective contraception.

Polyclonal hyper immunoglobulin: A proven treatment and prophylaxis platform for passive immunization to address existing and emerging diseases

Passive immunization with polyclonal hyper immunoglobulin (HIG) therapy represents a proven strategy by transferring immunoglobulins to patients to confer immediate protection against a range of pathogens including infectious agents and toxins. Distinct from active immunization, the protection is passive and the immunoglobulins will clear from the system; therefore, administration of an effective dose must be maintained for prophylaxis or treatment until a natural adaptive immune response is mounted or the pathogen/agent is cleared. The current review provides an overview of this technology, key considerations to address different pathogens, and suggested improvements. The review will reflect on key learnings from development of HIGs in the response to public health threats due to Zika, influenza, and severe acute respiratory syndrome coronavirus 2.

Risk Estimation of Sexual Transmission of Zika Virus-United States, 2016-2017

BACKGROUND

Zika virus (ZIKV) can be transmitted sexually but the risk of sexual transmission remains unknown. Most evidence of sexual transmission is from partners of infected travelers returning from areas with ZIKV circulation.

METHODS

We used data from the US national arboviral disease surveillance system on travel- and sexually acquired ZIKV disease cases during 2016-2017 to develop individual-level simulations for estimating risk of male-to-female, male-to-male, and female-to-male sexual transmission of ZIKV via vaginal and/or anal intercourse. We specified parametric distributions to characterize individual-level variability of parameters for ZIKV persistence and sexual behaviors.

RESULTS

Using ZIKV RNA persistence in semen/vaginal fluids to approximate infectiousness duration, male-to-male transmission had the highest estimated probability (1.3% [95% confidence interval, CI, .4%-6.0%] per anal sex act), followed by male-to-female and female-to-male transmission (0.4% [95% CI, .3%-.6%] per vaginal/anal sex act and 0.1% [95% CI, 0%-.8%] per vaginal sex act, respectively). Models using viral isolation in semen vs RNA detection to approximate infectiousness duration predicted greater risk of sexual transmission.

CONCLUSIONS

While likely insufficient to maintain sustained transmission, the estimated risk of ZIKV transmission through unprotected sex is not trivial and is especially important for pregnant women, as ZIKV infection can cause severe congenital disorders.

Determining the impact of the Zika pandemic on primary care providers' contraceptive counseling of non-pregnant patients in the US: a mixed methods study

BACKGROUND

Global pandemics like Zika (ZIKV) factor into pregnancy planning and avoidance, yet little is known about how primary care providers (PCPs) incorporate public health guidance into contraceptive counseling. Study objectives include: 1) determining the impact of the ZIKV pandemic on contraceptive counseling changes; and 2) assessing PCP knowledge and practice regarding contraception, ZIKV, and CDC ZIKV guidelines.

METHODS

Study components included: (1) a retrospective review of electronic health records of non-pregnant, reproductive age women presenting for preventive health visits between 2014 and 2017 assessed using interrupted time series analyses (ITSA) to identify changes in documentation of ZIKV risk assessment and contraceptive counseling; and (2) a sequential, cross-sectional study with quantitative surveys and qualitative, semi-structured interviews of PCPs providing preventive care to non-pregnant patients at eight federally qualified health centers in Utah. We performed descriptive analyses on survey data and analyzed qualitative data for dominant themes using a modified Health Belief Model.

RESULTS

We conducted 6634 chart reviews yielding 9840 visits. The ITSA did not reveal changes in ZIKV risk assessment or contraceptive counseling. Twenty-two out of 40 (55%) eligible providers participated in the provider component. Participants averaged 69 and 81% correct on contraceptive and ZIKV knowledge questions, respectively. Sixty-five percent reported counseling consistent with CDC ZIKV guidelines. Qualitative analysis found providers unlikely to prioritize ZIKV risk assessment in contraceptive counseling for non-pregnant patients.

CONCLUSIONS

PCPs who care for non-pregnant women are knowledgeable about contraception and ZIKV; however, there was no change in ZIKV risk assessment or contraceptive counseling. This stresses the importance of developing strategies to improve guideline uptake.

Zika Prevention Behaviors Among Women of Reproductive Age in Puerto Rico, 2016

INTRODUCTION

Zika virus is primarily transmitted through mosquito bites. Because Zika virus infection during pregnancy can cause serious birth defects, reproductive-aged women need protection from Zika virus infection. This report describes Zika virus prevention behaviors among women aged 18-49 years and assesses whether pregnancy status and healthcare provider counseling increases Zika virus prevention behaviors.

METHODS

A population-based cell phone survey of women aged 18-49 years living in Puerto Rico was conducted in July-November 2016. Data were analyzed in 2018-2019. Prevalence estimates and 95% CIs were calculated for Zika virus prevention behaviors. Adjusted prevalence ratios were estimated to examine the association of pregnancy status with healthcare provider counseling on Zika virus prevention behaviors, controlling for age, education, and health insurance status.

RESULTS

Most women reported using screens on open doors/windows (87.7%) and eliminating standing water in/around their homes (92.3%). Other Zika virus prevention behaviors were less common (<33%). In adjusted analysis, pregnant women were more likely than women not at risk for unintended pregnancy to report using mosquito repellent every/most days (adjusted prevalence ratio=1.44, 95% CI=1.13, 1.85). Healthcare provider counseling was associated with receiving professional spraying/larvicide treatment (adjusted prevalence ratio=1.42, 95% CI=1.17, 1.74), sleeping under a bed net (adjusted prevalence ratio=2.37, 95% CI=1.33, 4.24), using mosquito repellent (adjusted prevalence ratio=1.57, 95% CI=1.40, 1.77), and wearing long sleeves/pants (adjusted prevalence ratio=1.32, 95% CI=1.12, 1.55).

CONCLUSIONS

Receipt of healthcare provider counseling was more consistently associated with Zika virus prevention behaviors than pregnancy status. Healthcare provider counseling is an important strategy for increasing the uptake of Zika virus prevention behaviors among women aged 18-49 years.

Complexities of Zika Diagnosis and Evaluation in a U.S. Congenital Zika Program

The objective of the study was to describe the complexity of diagnosis and evaluation of Zika-exposed pregnant women/fetuses and infants in a U.S. Congenital Zika Program. Pregnant women/fetuses and/or infants referred for clinical evaluation to the Congenital Zika Program at Children's National (Washington, DC) from January 2016 to June 2018 were included. We recorded the timing of maternal Zika-virus (ZIKV) exposure and ZIKV laboratory testing results. Based on laboratory testing, cases were either confirmed, possible, or unlikely ZIKV infection. Prenatal and postnatal imaging by ultrasound and/or magnetic resonance imaging (MRI) were categorized as normal, nonspecific, or as findings of congenital Zika syndrome (CZS). Of 81 women-fetus/infant pairs evaluated, 72 (89%) had confirmed ZIKV exposure; 18% of women were symptomatic; only a minority presented for evaluation within the time frame for laboratory detection. Zika virus could only be confirmed in 29 (40%) cases, was possible in 26 (36%) cases, and was excluded in 17 (24%) cases. Five cases (7%) had prenatal ultrasound and MRI findings of CZS, but in only three was ZIKV confirmed by laboratory testing. Because of timing of exposure to presentation, ZIKV infection could not be excluded in many cases. Neuroimaging found CZS in 7% of cases, and in many patients, there were nonspecific imaging findings that warrant long-term follow-up. Overall, adherence to postnatal recommended follow-up evaluations was modest, representing a barrier to care. These challenges may be instructive to future pediatric multidisciplinary clinics for congenital infectious/noninfectious threats to pregnant women and their infants.

Zika Virus

Zika virus (ZIKV), a neurotropic single-stranded RNA flavivirus, remains an important cause of congenital infection, fetal microcephaly, and Guillain-Barré syndrome in populations where ZIKV has adapted to a nexus involving the Aedes mosquitoes and humans. To date, outbreaks of ZIKV have occurred in Africa, Southeast Asia, the Pacific islands, the Americas, and the Caribbean. Emerging evidence, however, suggests that the virus also has the potential to cause infections in Europe, where autochtonous transmission of the virus has been identified. This review focuses on evolving ZIKV epidemiology, modes of transmission and host-virus interactions. The clinical manifestations, diagnostic issues relating to cross-reactivity to the dengue flavivirus and concerns surrounding ZIKV infection in pregnancy are discussed. In the last section, current challenges in treatment and prevention are outlined.

Teratogen update: Zika virus and pregnancy

Zika virus was first identified in Uganda in 1947 but received little attention until 2015 when a large outbreak of Zika virus illness followed by an increased number of babies born with microcephaly occurred in Brazil. Zika virus spread rapidly throughout the Americas, and in 2016 was identified as a cause of microcephaly and other serious birth defects. Since that time, much has been learned about the Zika virus. The virus is primarily spread by the bite of Aedes species mosquitoes; however, other forms of transmission (e.g., sexual and intrauterine) have been recognized. Although postnatal Zika virus infection typically causes mild or no symptoms, effects on infants born to prenatally infected mothers can be severe and include structural birth defects and neurodevelopmental effects. The risk of a structural birth defect among infants born to mothers with confirmed or suspected Zika virus infection during pregnancy has ranged from 5 to 10%. The timing of Zika infection during pregnancy affects risk, with higher risks with the first-trimester infection. Neurodevelopmental effects are seen even in infants who appear normal in the newborn period. Although cases of Zika virus infection have fallen in the Americas, the Zika virus remains an active threat in some regions of the world. The development of a Zika vaccine will require continued focus and investment. Until a Zika vaccine is available, prevention efforts for pregnant women include avoidance of travel to areas with active Zika transmission, avoidance of mosquito bites for those living in or traveling to areas with Zika transmission, and protection against sexual transmission.

Sustained maternal antibody and cellular immune responses in pregnant women infected with Zika virus and mother to infant transfer of Zika-specific antibodies

PROBLEM

Evaluation of Zika virus (ZIKV)-specific humoral and cellular immune response in pregnant women exposed to ZIKV.

METHOD OF STUDY

In this observational, prospective cohort study, we recruited pregnant women presenting for prenatal ultrasound for ZIKV exposure at a single academic teaching hospital in Boston, MA from November 2016 to December 2018. We collected blood, urine, and cervicovaginal swabs antepartum, intrapartum, and postpartum; and cord blood and placenta at delivery. We used experimental assays to calculate quantitative viral loads, ZIKV-specific immunoglobulin titers, and ZIKV-specific T-cell responses.

RESULTS

We enrolled 22 participants, three of which had serologic-confirmed ZIKV infection. No participants demonstrated sustained ZIKV shedding. ZIKV-specific IgG/IgM antibody was sustained throughout pregnancy and postpartum. ZIKV envelope and capsid-specific T-cell responses were also observed, albeit inconsistent. No newborns in this cohort had congenital Zika syndrome. Infant cord blood of infected mothers exhibited ZIKV-specific IgG, but not IgM antibodies.

CONCLUSION

We detected a robust, prolonged maternal humoral immune response to ZIKV during pregnancy and postpartum. We also demonstrated evidence for efficient transplacental antibody transfer from mother to infant at birth, supporting the importance of neonatal passive immunity to ZIKV. Maternal T-cell responses were less consistent among pregnant women infected with ZIKV.

Assessment of contraceptive use in Puerto Rico during the 2016 Zika virus outbreak

OBJECTIVES

The objectives of this analysis were to 1) estimate prevalence of contraceptive use among women at risk for unintended pregnancy and 2) identify correlates of contraceptive use among women with ongoing or potential need for contraceptive services in Puerto Rico during the 2016 Zika virus (ZIKV) outbreak.

STUDY DESIGN

We conducted a cell-phone survey July-November, 2016. Women aged 18-49 years living in Puerto Rico were eligible. We completed 3059 interviews; the overall response rate was 69.2%. After weighting, the data provide population-based estimates. For this analysis, we included women at risk for unintended pregnancy, and assessed ongoing or potential need for contraceptive services in this group, excluding women using permanent contraceptive methods.

RESULTS

Most women reported using contraception (82.8%), and use increased with age. Female sterilization and male condoms were most frequently reported (40.8% and 17.1%, respectively). Among women with ongoing or potential need for contraceptive services, 24.7% talked to a healthcare provider about ZIKV, and 31.2% reported a change in childbearing intentions due to ZIKV. Most women were at least a little worried about getting infected with ZIKV (74.3%) or having a baby with a birth defect (80.9%). Being very worried about getting infected with ZIKV and already having Zika were significantly associated with use of any contraception (adjusted prevalence ratio: 1.19, 95% CI: 1.03-1.38 and 1.32, 95% CI: 1.01-1.72, respectively).

CONCLUSIONS

These findings underscore the need for regular contraceptive prevalence studies to inform programs about contraceptive needs, especially during public health emergencies.

IMPLICATIONS

When the 2016 Zika virus outbreak began in Puerto Rico there were no recent population-based data available on contraceptive prevalence. To fill this information gap, we conducted a population-based survey. Our findings provided baseline contraceptive prevalence estimates to support response planning and allocation of health resources.

Embedded model discrepancy: A case study of Zika modeling

Mathematical models of epidemiological systems enable investigation of and predictions about potential disease outbreaks. However, commonly used models are often highly simplified representations of incredibly complex systems. Because of these simplifications, the model output, of, say, new cases of a disease over time or when an epidemic will occur, may be inconsistent with the available data. In this case, we must improve the model, especially if we plan to make decisions based on it that could affect human health and safety, but direct improvements are often beyond our reach. In this work, we explore this problem through a case study of the Zika outbreak in Brazil in 2016. We propose an embedded discrepancy operator-a modification to the model equations that requires modest information about the system and is calibrated by all relevant data. We show that the new enriched model demonstrates greatly increased consistency with real data. Moreover, the method is general enough to easily apply to many other mathematical models in epidemiology.

Women's Awareness and Healthcare Provider Discussions about Zika Virus during Pregnancy, United States, 2016-2017

We surveyed women with a recent live birth who resided in 16 US states and 1 city during the 2016 Zika outbreak. We found high awareness about the risk of Zika virus infection during pregnancy and about advisories to avoid travel to affected areas but moderate levels of discussions with healthcare providers.

Local Transmission of Zika Virus in Miami-Dade County: The Florida Department of Health Rises to the Challenge

As early as 2015, Florida and Centers for Disease Control and Prevention (CDC) public health officials recognized the potential danger of Zika for US residents and visitors. The Zika virus, a mosquito-borne flavivirus, is transmitted through the bite of the Aedes aegypti mosquito. A physician in Miami-Dade notified the Florida Department of Health (DOH) of the first non-travel-related Zika case in the United States. A 23-year old pregnant woman had presented on July 7, 2016, at 23 weeks of gestation, with a 3-day history of fever, widespread pruritic rash, and sore throat. Three more cases, involving men, were reported in Dade and Broward counties. These notifications set into motion additional activities from the DOH's Zika Playbook: increased mosquito surveillance; collaboration with the CDC on recommendations for mosquito abatement techniques; and increased awareness of the risks of Zika. In August, the department reported that active transmission of Zika virus was occurring in one small area in Miami-Dade County known as Wynwood. Mosquito trapping in the area with local transmission identified large numbers of the Zika vector, Aedes aegypti females and a large number of mosquito larval sites. Control efforts included larviciding, eliminating standing water, and backpack and truck spraying of insecticides. A communication strategy was developed that addressed risk mitigation, public concerns over application of noxious pesticides, loss of tourist revenue, and reproductive issues. It was reported on December 28, 2016, that there had been 256 locally acquired cases of infection of Zika, 1011 travel-related cases, and 208 pregnant women with laboratory evidence of Zika. At the end of 2018, 2 years after active Zika virus transmission was controlled in Florida, there have been 101 reported cases of Zika during 2018 but none have been linked to local transmission.

The Effects of Zika Virus Risk Coverage on Familiarity, Knowledge and Behavior in the U.S. - A Time Series Analysis Combining Content Analysis and a Nationally Representative Survey

This study assessed the effects of the February through September 2016 American news media's coverage of Zika Virus (ZIKV) risk on the U.S. public's familiarity, knowledge and behavior in the form of interpersonal discussions. A content analysis (N = 2,782 pieces) revealed that the Rio Olympic Games elicited a spike in coverage of Zika. We also found that newsworthy and easy- to- depict aspects of the disease, specifically its transmission by mosquitoes and its relation to microcephaly were covered more extensively than its sexual transmission and transmissibility from an infected person who is asymptomatic. Nevertheless, survey data over the same period of time (N = 37,180 respondents) revealed that the general amount of coverage, rather than the specifics about Zika transmission and its consequences, influenced the public's familiarity, knowledge, and behavior.

When could human challenge trials be deployed to combat emerging infectious diseases? Lessons from the case of a Zika virus human challenge trial

Human challenge trials (HCTs) deliberately infect participants in order to test vaccines and treatments in a controlled setting, rather than enrolling individuals with natural exposure to a disease. HCTs are therefore potentially powerful tools to prepare for future outbreaks of emerging infectious diseases. Yet when an infectious disease is emerging, there is often substantial risk and uncertainty about its complications, and few available interventions, making an HCT ethically complex. In light of the need to consider ethical issues proactively as a part of epidemic preparedness, we use the case of a Zika virus HCT to explore whether and when HCTs might be ethically justified to combat emerging infectious diseases. We conclude that emerging infectious diseases could be appropriate candidates for HCTs and we identify relevant considerations and provide a case example to illustrate when they might be ethically acceptable.

Preventing Sexual Transmission of Zika Virus Infection during Pregnancy, Puerto Rico, USA, 20161

We examined condom use throughout pregnancy during the Zika outbreak in Puerto Rico during 2016. Overall, <25% of women reported consistent condom use during pregnancy. However, healthcare provider counseling was associated with a 3-fold increase in consistent use, reinforcing the value of provider counseling in Zika prevention efforts.

Zika Virus and Other Emerging Arboviral Central Nervous System Infections

PURPOSE OF REVIEW

In recent years, we have observed the emergence and reemergence of a number of arthropod-borne viruses (arboviruses). Zika virus is the most recent addition to this group, first causing sporadic cases of uncomplicated febrile illness followed by sizeable outbreaks in the Pacific. However, the epidemiology and clinical features of Zika virus infection have changed rapidly and dramatically; it is now recognized as causing Guillain-Barré syndrome (GBS) in children and adults and congenital abnormalities in infected fetuses. This article reviews the epidemiology, clinical features, and diagnosis of Zika virus-associated neurologic illness and briefly reviews features of West Nile virus and Japanese encephalitis virus.

RECENT FINDINGS

Zika virus has emerged as a significant human pathogen in recent years. In 2015, it began to cause large outbreaks of febrile rash illness in South America and the Caribbean. During these large Zika virus outbreaks, a significant increase in the incidence of GBS was also observed in multiple countries/territories. Zika virus-associated GBS has several unique features, including a relatively short interval between febrile illness and GBS onset, an unusually high incidence among older people, and prominent cranial nerve abnormalities. Congenital Zika syndrome includes a myriad of abnormalities, including microcephaly, lissencephaly, hydrocephalus, arthrogryposis, and parenchymal calcifications. Currently, no treatment has been identified for Zika virus, although work on vaccines is under way.

SUMMARY

Arboviruses continue to surprise us with unexpected emergence in various locations, the nature of clinical illness, and outcomes. Zika virus presents a classic example of this type of emergence. Ongoing surveillance will be needed to evaluate the long-term pattern of Zika virus and related arboviruses.

Modes of Transmission of Zika Virus

For >60 years, Zika virus (ZIKV) has been recognized as an arthropod-borne virus with Aedes species mosquitoes as the primary vector. However in the past 10 years, multiple alternative routes of ZIKV transmission have been identified. We review the available data on vector and non-vector-borne modes of transmission and interventions undertaken, to date, to reduce the risk of human infection through these routes. Although much has been learned during the outbreak in the Americas on the underlying mechanisms and pathogenesis of non-vector-borne ZIKV infections, significant gaps remain in our understanding of the relative incidence of, and risk from, these modes compared to mosquito transmission. Additional research is urgently needed on the risk, pathogenesis, and effectiveness of measures to mitigate non-vector-borne ZIKV transmission.

Zika Virus and Pregnancy Concerns

Understanding Zika virus (ZIKV) transmission and the risk of birth defects associated with infection during the childbearing years is imperative. Current knowledge helps guide communication, prevention, and planning efforts between health care providers and female patients of childbearing age. Providers must follow updated data and implement ongoing rapid, sensitive, and specific screening and diagnostic testing for ZIKV. Surveillance of infants with known, in utero ZIKV exposure or infection must be maintained to gain a broader understanding of potential defects or injuries that are not immediately obvious at birth and in early infancy.

Zika Virus Infection and Implications for Reproduction

Zika virus infection during pregnancy can have devastating effects on the foetus leading to congenital Zika syndrome. It is relevant therefore for couples living in countries with endemic Zika virus to understand the strategies they can utilise to reduce the chance of infection. In addition, couples planning pregnancy, or who are already pregnant, travelling to countries with Zika virus need to be informed of the potential risk and implications for future reproductive planning.

Preconception Care for the General Ob/Gyn

Preconception counseling is an important aspect of the care of reproductive-aged women. Asking each woman with each interaction her wishes regarding pregnancy allows the health care provider to investigate her history. The areas to review include environmental toxins, nutrition, genetics, substance abuse, medical conditions, infectious diseases, and psychosocial issues. Then preconception counseling can be individualized. The goal is to decrease or eliminate risks that can cause detriments to the patient or her future pregnancies.

Emerging arboviruses and implications for pediatric transplantation: A review

Recent years have brought a rise in newly emergent viral infections, primarily in the form of previously known arthropod-transmitted viruses that have increased significantly in both incidence and geographical range. Of particular note are DENV, CHIKV, and ZIKV, which are transmitted mostly by Aedes species of mosquitoes that exhibit a wide and increasing global distribution. Being important pathogens for the general population, these viruses have the potential to be devastating in the international transplant community, with graft rejection and death as possible outcomes of infection. In this review, we discuss the current state of knowledge for these viruses as well as repercussions of infection in the solid organ and HSCT population, with a focus, when possible, on pediatric patients.

Complete Genome Sequences of Spondweni Viruses Isolated between 1958 and 1960

Here, we report the complete genome sequences of 14 Spondweni viruses isolated in South Africa and Mozambique between 1958 and 1960. The sequences comprise 13 mosquito isolates and 1 human isolate following a documented laboratory infection. This study expands the publicly available data for this neglected virus from 4 to 18 sequences.

Mosquito-Borne Diseases

Mosquito-borne diseases have become more common as previously geographically isolated diseases have spread globally. Chikungunya, dengue, Japanese encephalitis, malaria, West Nile, yellow fever, and Zika are a few of the common and emerging viral diseases spread by mosquitoes. A thorough patient history, physical, and knowledge of diagnostic testing based on symptom duration is important to make a quick and accurate diagnosis. Because the treatment for many of these diseases is supportive, the emphasis is on reducing risk and spread of infection.

Zika virus in American Samoa: challenges to prevention in the context of health disparities and non-communicable disease

BACKGROUND

Zika virus (ZIKV) is linked to deleterious foetal and neonate outcomes. Maternal exposure to ZIKV through mosquitoes and sexual fluids creates a public health challenge for communities and policymakers, which is exacerbated by high levels of chronic non-communicable diseases in American Samoa.

AIM

This study aimed to identify structural barriers to ZIKV prevention in American Samoa and situate them within locally relevant cultural and epidemiological contexts.

SUBJECTS AND METHODS

This study assessed knowledge, attitudes and access to ZIKV prevention among 180 adults in American Samoan public health clinics. It queried knowledge about pre-natal care, protection against mosquitoes and condom use.

RESULTS

Women were most likely to identify pre-natal care as important. The majority of participants were able to identify how to prevent mosquito bites, but may have been unable to follow through due to socioeconomic and infrastructure limitations. Few participants identified condom use as a preventative measure against ZIKV. Prevention misconceptions were most pronounced in women of low socioeconomic status.

CONCLUSIONS

These findings reinforce the need for a multi-pronged approach to ZIKV. This study highlights the need for information on culturally specific barriers and recognition of additional challenges associated with dual burden in marginal populations where social inequalities exacerbate health issues.

A cross-sectional analysis of Zika virus infection in symptomatic and asymptomatic non-pregnant travellers: Experience of a European reference center during the outbreak in the Americas

BACKGROUND

Zika virus (ZIKV) infection a concern to travellers because of potential sexual transmission and adverse pregnancy outcomes.

OBJECTIVE

To describe our experience in diagnosing ZIKV in travellers returning from endemic territories.

METHOD

Travellers were evaluated for ZIKV at our clinic in a 12-month period during the outbreak, using ZIKV-specific RT-PCR and anti-ZIKV Immunoglobulin M/G ELISA when symptomatic, and ELISA only for asymptomatic travellers, preferably from 20 days after the last exposure. All positive ELISA results were subject to confirmation by Virus Neutralization Testing. We estimated post-test probabilities of ZIKV in asymptomatic travellers.

RESULTS

Of 462 travellers, 227 reported symptoms and 235 did not. Asymptomatic travellers had similar baseline characteristics, but were younger (median age 31 vs. 33 years, p = 0.01) and had reproductive concerns more often (75.8% vs. 24.2%). ZIKV infection was confirmed in 49 cases: 46/227 (20.3%) were symptomatic and 3/235 (1.3%) asymptomatic. Rash (positive likelihood ratio (LRP) 5.6) and conjunctivitis (LRP 10.8) predicted ZIKV infection. The post-test probability of a negative ELISA-result at 20-25 days was below 0.1%.

CONCLUSION

ZIKV infection was frequent in symptomatic, but not in asymptomatic travellers. We consider negative ELISA results at 20-25 days after exposure a safe strategy to rule out ZIKV infection. Testing for ZIKV-specific antibodies within this timeframe could be particularly valuable in the management of returning travellers who wish to conceive.

Update: Interim Guidance for Preconception Counseling and Prevention of Sexual Transmission of Zika Virus for Men with Possible Zika Virus Exposure - United States, August 2018

Zika virus infection can occur as a result of mosquitoborne or sexual transmission of the virus. Infection during pregnancy is a cause of fetal brain abnormalities and other serious birth defects (1,2). CDC has updated the interim guidance for men with possible Zika virus exposure who 1) are planning to conceive with their partner, or 2) want to prevent sexual transmission of Zika virus at any time (3). CDC now recommends that men with possible Zika virus exposure who are planning to conceive with their partner wait for at least 3 months after symptom onset (if symptomatic) or their last possible Zika virus exposure (if asymptomatic) before engaging in unprotected sex. CDC now also recommends that for couples who are not trying to conceive, men can consider using condoms or abstaining from sex for at least 3 months after symptom onset (if symptomatic) or their last possible Zika virus exposure (if asymptomatic) to minimize their risk for sexual transmission of Zika virus. All other guidance for Zika virus remains unchanged. The definition of possible Zika virus exposure remains unchanged and includes travel to or residence in an area with risk for Zika virus transmission (https://wwwnc.cdc.gov/travel/page/world-map-areas-with-zika) or sex without a condom with a partner who traveled to or lives in an area with risk for Zika virus transmission. CDC will continue to update recommendations as new information becomes available.

Sexual transmission of Zika virus and other flaviviruses: A living systematic review

BACKGROUND

Health authorities in the United States and Europe reported an increasing number of travel-associated episodes of sexual transmission of Zika virus (ZIKV) following the 2015-2017 ZIKV outbreak. This, and other scientific evidence, suggests that ZIKV is sexually transmissible in addition to having its primary mosquito-borne route. The objective of this systematic review and evidence synthesis was to clarify the epidemiology of sexually transmitted ZIKV.

METHODS AND FINDINGS

We performed a living (i.e., continually updated) systematic review of evidence published up to 15 April 2018 about sexual transmission of ZIKV and other arthropod-borne flaviviruses in humans and other animals. We defined 7 key elements of ZIKV sexual transmission for which we extracted data: (1) rectal and vaginal susceptibility to infection, (2) incubation period following sexual transmission, (3) serial interval between the onset of symptoms in a primary and secondary infected individuals, (4) duration of infectiousness, (5) reproduction number, (6) probability of transmission per sex act, and (7) transmission rate. We identified 1,227 unique publications and included 128, of which 77 presented data on humans and 51 presented data on animals. Laboratory experiments confirm that rectal and vaginal mucosae are susceptible to infection with ZIKV and that the testis serves as a reservoir for the virus in animal models. Sexual transmission was reported in 36 human couples: 34/36 of these involved male-to-female sexual transmission. The median serial symptom onset interval in 15 couples was 12 days (interquartile range: 10-14.5); the maximum was 44 days. We found evidence from 2 prospective cohorts that ZIKV RNA is present in human semen with a median duration of 34 days (95% CI: 28-41 days) and 35 days (no CI given) (low certainty of evidence, according to GRADE). Aggregated data about detection of ZIKV RNA from 37 case reports and case series indicate a median duration of detection of ZIKV of 40 days (95% CI: 30-49 days) and maximum duration of 370 days in semen. In human vaginal fluid, median duration was 14 days (95% CI: 7-20 days) and maximum duration was 37 days (very low certainty). Infectious virus in human semen was detected for a median duration of 12 days (95% CI: 1-21 days) and maximum of 69 days. Modelling studies indicate that the reproduction number is below 1 (very low certainty). Evidence was lacking to estimate the incubation period or the transmission rate. Evidence on sexual transmission of other flaviviruses was scarce. The certainty of the evidence is limited because of uncontrolled residual bias.

CONCLUSIONS

The living systematic review and sexual transmission framework allowed us to assess evidence about the risk of sexual transmission of ZIKV. ZIKV is more likely transmitted from men to women than from women to men. For other flaviviruses, evidence of sexual transmissibility is still absent. Taking into account all available data about the duration of detection of ZIKV in culture and from the serial interval, our findings suggest that the infectious period for sexual transmission of ZIKV is shorter than estimates from the earliest post-outbreak studies, which were based on reverse transcription PCR alone.

Emerging sexually transmitted viral infections: 2. Review of Zika virus disease

A sudden increase in the number of newborn infants with microcephaly in Brazil in 2015 brought Zika virus (ZIKV), a less-known infection, to public attention. The rapid increase in the number of cases across the Americas and the devastating complications of infection with ZIKV highlighted the gravity of the situation. Within a relatively short period of time, our knowledge of this infection has significantly increased. This includes the realisation that ZIKV can be sexually transmitted. The aim of the present article is to provide a concise summary on this novel sexually transmitted infection linked to human birth defects and Guillain-Barre Syndrome. According to World Health Organization, individuals living outside areas of ZIKV mosquito transmission where one or both partners have been exposed to ZIKV should abstain from sex or have sex with condoms for at least six months after the last day of possible exposure.

Epidemiological Characteristics and Laboratory Findings of Zika Virus Cases in New York City, January 1, 2016-June 30, 2017

BACKGROUND

An outbreak of Zika virus (ZIKV) began in May 2015 in Brazil and rapidly spread throughout the Americas; New York City (NYC) has a diverse population with ∼1.8 million residents who were born in ZIKV-affected areas. Before July 24, 2017, the Centers for Disease Control and Prevention (CDC) ZIKV testing recommendations included nucleic acid amplification-based tests for serum and urine specimens collected ≤14 days of illness onset or last potential exposure, and ZIKV immunoglobulin M (IgM) assay when ZIKV RNA is not detected or for specimens collected within 2-12 weeks of illness onset or last potential exposure, followed by a plaque reduction neutralization test (PRNT). However, the New York public health laboratories and commercial laboratories tested specimens collected beyond these time frames.

METHODS

We analyzed 1080 noncongenital ZIKV cases in NYC residents who met the Council for State and Territorial Epidemiologist's ZIKV case definitions.

RESULTS

Among cases, 98% were travel associated, 1% were sexually transmitted, and 1% had unknown exposures; 412 (38%) cases were pregnant women. Of 672 patients with ZIKV RNA detected in serum or urine specimens, 48 (7%) tested positive >14 days after either symptom onset or last potential exposure date (range 15-99 days). Of 390 patients diagnosed based on serology alone (i.e., not tested or not detectable for ZIKV RNA), 60 (15%) had a positive ZIKV IgM and PRNT >12 weeks after symptom onset or last potential exposure date (range 85-273 days).

CONCLUSION

Our findings correspond with CDC's updated guidance to test symptomatic pregnant women up to 12 weeks past onset of symptoms. ZIKV IgM antibody testing may also be warranted for pregnant women regardless of symptoms if their exposure occurred during their pregnancy or periconception period. Providers should understand the scope of diagnostic testing and its limitations to appropriately counsel patients, especially pregnant women.

Sexually Transmitted Infection Prevention With Long-Acting Reversible Contraception: Factors Associated With Dual Use

BACKGROUND

Long-acting reversible contraception (LARC) is extremely effective in preventing pregnancy; however, it does not provide sexually transmitted infection (STI) prevention. Therefore, dual use is recommended for the prevention of STIs, in addition to pregnancy, by using LARC methods with condoms. This study assessed factors associated with LARC only use and dual-LARC and condom use among college women.

METHODS

The National College Health Assessment-II Fall 2012 to 2013 was used for this analysis. The analytic sample was restricted to women who used a LARC method (ie, intrauterine device or implant) (N = 1658). The main outcome was dual method use, LARC and condom, at last sex. An adjusted logistic regression model assessed sociodemographic factors (age, relationship, race), health care utilization (routine gynecological examination), and sexual behavior (number of partners) as factors associated with dual condom-LARC use at the last time of vaginal-sex. Prevalence ratios (PR) and 95% confidence intervals (CI) were estimated.

RESULTS

Among women reporting LARC use, 24% used a condom. Dual users were less likely to have only 1 sexual partner (adjusted PR [aPR], 0.66; 95% CI, 0.54-0.81) and be in a relationship. Dual users were more likely than LARC-only users to be Hispanic (aPR, 1.34; 95% CI, 1.01-1.78), black (aPR, 1.40; 95% CI, 1.07-1.83), and biracial/multiracial (aPR, 1.38; 95% CI, 1.10-1.73).

CONCLUSIONS

These findings illustrate differences between dual-condom LARC and LARC-only college users. It is likely that relationship status and number of partners influences perceived risk for STIs and decision making for dual use among this population.

The effect of sexual transmission on Zika virus dynamics

Zika virus is a human disease that may lead to neurological disorders in affected individuals, and may be transmitted vectorially (by mosquitoes) or sexually. A mathematical model of Zika virus transmission is formulated, taking into account mosquitoes, sexually active males and females, inactive individuals, and considering both vector transmission and sexual transmission from infectious males to susceptible females. Basic reproduction numbers are computed, and disease control strategies are evaluated. The effect of the incidence function used to model sexual transmission from infectious males to susceptible females is investigated. It is proved that for such functions that are sublinear, if the basic reproduction [Formula: see text], then the disease dies out and [Formula: see text] is a sharp threshold. Moreover, under certain conditions on model parameters and assuming mass action incidence for sexual transmission, it is proved that if [Formula: see text], there exists a unique endemic equilibrium that is globally asymptotically stable. However, under nonlinear incidence, it is shown that for certain functions backward bifurcation and Hopf bifurcation may occur, giving rise to subthreshold equilibria and periodic solutions, respectively. Numerical simulations for various parameter values are displayed to illustrate these behaviours.

Using a Health Literacy Analytic Framework to Explore Zika Virus and Reproductive Health

Background:

The emergence of Zika virus as sexually transmissible and associated with birth defects may affect reproductive planning and contraception use for people in Florida.

Objective:

This exploratory study employed a health literacy analytic framework to explore knowledge, attitudes, beliefs, and behaviors related to reproductive health in the context of Zika among reproductive-age women and men in Florida.

Methods:

Reproductive-age people in Florida (N = 40) were interviewed between September and December 2016 about their knowledge, attitudes, beliefs, and behaviors regarding Zika and reproductive health. Thematic analysis using a health literacy framework was employed.

Key Results:

Participants reported they would use reputable online sources to access Zika information. Whereas participants generally understood Zika outcomes, transmission, and symptoms, they reported hearing more prevention messages on mosquito transmission compared to sexual transmission. Overall, participants reported Zika was not concerning given their appraisal of personal circumstances. Participants were confident they could prevent Zika via sexual transmission despite not following the recommended guidelines. Participants discussed how their understanding of Zika changed their behaviors related to mosquito control but not through sexual transmission.

Conclusions:

This study illustrated a disconnect between reproductive-age people's understanding of Zika-related prevention information and their reproductive decision-making behavior. Strategies to promote appraisal of risk for sexual transmission of Zika, infection, and unintended pregnancy are needed. [HLRP: Health Literacy Research and Practice. 2018;2(2):e78–e87.]

Plain Language Summary:

Men and women of reproductive age in Florida may be at risk for Zika virus and related negative health outcomes. This study assessed how Florida men and women find, understand, and evaluate Zika-related health information, and how that applies to their prevention behaviors. This study used health literacy as an analytic framework for an emerging health issue.

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

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

Current priorities in the Zika response

Zika virus (ZIKV), a single-stranded RNA virus of the Flaviviridae family, is an arbovirus (viruses transmitted by arthropods) transmitted to humans and non-human primates through the bites of infected female Aedes sp. mosquitoes. Although first isolated in 1947, it only recently emerged as a global threat, present in several countries resulting in a pandemic scenario. ZIKV infections may have severe outcomes, such as neurological impairment, and with the intrinsic ability of inducing microcephaly in fetuses of infected pregnant women, the virus has become a major public health problem. This review discusses some advances in diagnosis; vaccine development and the problems associated with their administration; the importance of the cross-reactivity with other flaviviruses in protecting or worsening the disease; the implications of the recent outbreak caused by the virus in the world; and future prospects for the complete understanding of this disease.

Public Health Approach to Addressing the Needs of Children Affected by Congenital Zika Syndrome

We have learned much about the short-term sequelae of congenital Zika virus (ZIKV) infection since the Centers for Disease Control and Prevention activated its ZIKV emergency response in January 2016. Nevertheless, gaps remain in our understanding of the full spectrum of adverse health outcomes related to congenital ZIKV infection and how to optimize health in those who are affected. To address the remaining knowledge gaps, support affected children so they can reach their full potential, and make the best use of available resources, a carefully planned public health approach in partnership with pediatric health care providers is needed. An essential step is to use population-based data captured through surveillance systems to describe congenital Zika syndrome. Another key step is using collected data to investigate why some children exhibit certain sequelae during infancy and beyond, whereas others do not, and to describe the clustering of anomalies and the timing of when these anomalies occur, among other research questions. The final critical step in the public health framework for congenital Zika syndrome is an intervention strategy with evidence-based best practices for longer-term monitoring and care. Adherence to recommended evaluation and management procedures for infants with possible congenital ZIKV infection, including for those with less obvious developmental and medical needs at birth, is essential. It will take many years to fully understand the effects of ZIKV on those who are congenitally infected; however, the lifetime medical and educational costs as well as the emotional impact on affected children and families are likely to be substantial.

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.

A survey of the knowledge, attitudes and practices on Zika virus in new York City

BACKGROUND

Over 900 travel-associated Zika virus cases have been identified in New York City (NYC), New York. A survey was administered in NYC adapted from the Knowledge, Attitudes, and Practices (KAP) survey on Zika virus developed by the World Health Organization (WHO).

METHODS

A standardized, self-administered, anonymous questionnaire was administered to a convenience sample in Manhattan and the Bronx from June 30th, 2016 to October 21st, 2016. Responses were grouped into six domains based on the content and structure of the questions and were summarized using descriptive statistics or converted into a continuous knowledge score and assessed for associations with pregnancy status and travel history using linear regression.

RESULTS

There were 224 respondents with a mean age of 33 (SD ± 11.6) with 77% (170/224) female and 24% (51/224) pregnant. The majority (98% (213/217)) were unable to identify all of the symptoms associated with acute Zika virus infection and all modes of transmission (97% (213/219)). Most participants (85% (187/219)) identified mosquitoes as a mode of transmission. 95% (116/122) reported an association between Zika virus and microcephaly. The most concerning aspect of Zika virus in 46% (91/200) was the risk of disabilities to babies, and risk of sexual transmission (25% (49/200)). When asked what precautions pregnant persons should to reduce the risk of transmission when traveling to a Zika endemic region, only 27% (50/185) identified using condoms during intercourse or refraining from intercourse while pregnant. Knowledge of Zika transmission is significantly positively associated with pregnancy status, but not with travel history.

CONCLUSION

Our results indicate an overall poor understanding of Zika virus symptoms and possible complications, transmission modes, and current recommended prevention guidelines. Pregnancy is positively associated with Knowledge of Zika Transmission, but not other knowledge scores. Reported travel history to Zika endemic regions is not significantly associated with Zika knowledge. There is a need for implementing future public health interventions that particularly focus on protection against Zika transmission, that Zika is sexually transmitted, and risks that the Guillain-Barré Syndrome poses a risk to adults.

Dengue virus not detected in human semen

Zika and Ebola viruses can persist in semen and pose a risk for sexual transmission. To determine if dengue virus, another flavivirus, is similarly detectable in semen, we performed dengue PCR on semen in five patients with acute dengue virus infection. All five tested negative, suggesting that dengue does not pose a risk for sexual transmission.

THE “UNHOLY” CHIKUNGUNYA–DENGUE–ZIKA TRINITY: A THEORETICAL ANALYSIS

Aedes aegypti is the vector for numerous diseases in humans and other (reservoir) hosts, such as chikungunya, dengue fever and Zika virus. A new deterministic model is designed and used to assess the dynamics of the three diseases in a population where Aedes mosquitoes are abundant. The model to be designed incorporates the recently-released imperfect vaccine against dengue virus (Dengvaxia[Formula: see text] vaccine by Sanofi Pasteur) as well as allow for sexual transmission of Zika. Further, the model allows for the assessment of the population-level impact of three biological hypotheses, namely a competitive dengue–chikungunya–Zika superinfection hierarchy, an antibody-dependent enhancement of dengue over Zika and that the Dengvaxia vaccine can induce reduced susceptibility to Zika infection in vaccinated individuals. After carrying out detailed theoretical analyses to gain insight into its qualitative features, the model is then fitted to the data recorded during the 2015–2016 outbreaks of the three diseases in Mexico. Simulations of the model show a reasonable fit to observed dynamics consistent with the competitive hierarchy assumed for the interactions of the viruses. Furthermore, Zika transmission dynamics is only mildly affected by changes in the parameter related to the infectiousness of Zika in relation to dengue, even in the region where antibody-dependent enhancement is assumed. The dengue vaccine has a very marginal impact on Zika transmission dynamics (and that the vaccine, no matter the coverage and efficacy levels, is unable to reduce the reproduction number for Zika transmission to a value less than unity). The model is extended to include the effect of seasonality and local weather variability (temperature and rainfall) on the dynamics of the three diseases. Simulations of the resulting non-autonomous model, using weather and demographic data for Mexico, show that for the current mean monthly rainfall value for Mexico, the burden of the three diseases increases with increasing mean monthly temperature in the range 16–29[Formula: see text]C, and decreases with increasing mean monthly temperature thereafter. Additionally, for the current fixed mean monthly temperature and rainfall data for Mexico, simulations show maximum transmission activity of all three diseases if the temperature and rainfall values lie in the range 25–26.4[Formula: see text]C and 90–128[Formula: see text]mm, respectively (these values are typically recorded in Mexico during the months of June, July and September). Simulations for two Mexican states (Oaxaca and Chiapas) where the three diseases are endemic show maximum transmission activity for all three diseases when temperature and rainfall lie in the ranges 20–25[Formula: see text]C and 51–102[Formula: see text]mm for Oaxaca (these ranges are recorded during the months of May through September) and 19–21[Formula: see text]C and 85–107[Formula: see text]mm for Chiapas (there ranges are recorded during the months of May, July, August and October), respectively. These simulations suggest suitable time when anti-mosquito control efforts should be intensified in Mexico (and the two selected states).

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.

Diagnosis of Zika Virus Infections: Challenges and Opportunities

Accurate diagnosis of Zika virus (ZIKV) infections has become a pressing need for the effective prevention and control of the epidemic. The findings that ZIKV infections are associated with birth defects and neurologic disease, and that the virus can be sexually transmitted, accentuate the need for accurate diagnostic testing for different applications new to the arbovirus field. Antibody response to related flaviviruses has long been known to be cross-reactive, and antibody detection of ZIKV is nonspecific in populations previously exposed to any of the four dengue viruses or West Nile virus, or vaccinated against yellow fever virus. Therefore, the diagnosis of ZIKV infections has increasingly depended on detection by nucleic acid tests. During the recent epidemic, tests authorized for emergency use have been utilized by public health laboratories and the commercial sector, but a more dependable and responsive diagnostic testing has yet to be developed.

Zika Virus Infection in Pregnancy: Maternal, Fetal, and Neonatal Considerations

An infection with the Zika virus (ZIKV) is usually mild, with nonspecific symptoms and most often asymptomatic. However, because of its causal relationship with severe congenital malformations, the ZIKV epidemic became an imperative for mobilization, renewed strategies for vector control, and biomedical research. A congenital Zika syndrome (CZS) has been characterized with 5 distinctive features that focus on brain development abnormalities (including microcephaly and brain calcifications), retinal manifestations, and defects on extremities including congenital contractures and hypertonia. The CZS could be just "the tip of the iceberg", pending the documentation of a spectrum of disease that could manifest later in life, from mild dysfunction to severe disease. It will be a matter of time for neurodevelopmental abnormalities, learning disabilities, and other unknown but yet-to-be-described outcomes to be associated with intrauterine ZIKV infection. In addition, ZIKV infection during pregnancy has been associated with other adverse outcomes. Reports mostly include ZIKV-affected pregnancies, and it will be difficult to clearly establish causality without appropriate control groups. We are summarizing some of the known or reported consequences of such infection during pregnancy. Women of reproductive age and particularly pregnant women are the most vulnerable to the adverse consequences of the ZIKV epidemic. Vector control programs need to be expanded to curtail new infections. Research is needed to develop safe and effective treatments, a preventive or therapeutic vaccine, and specific and sensitive tests and to diagnose and identify correlates of long-term immunity. Vaccines and treatments should be safe to be used in pregnancy. To do nothing would allow thousands of pregnant women to expose their fetuses to an infection that causes birth defects and other problems. Prenatal diagnosis technology development is necessary to be able to predict or diagnose adverse fetal outcomes related to ZIKV. Moreover, these tests should be used in a manner similar to the testing/screening method for neural tube defects and common chromosomal anomalies during prenatal care.

An update on Zika virus infection

The epidemic history of Zika virus began in 2007, with its emergence in Yap Island in the western Pacific, followed in 2013-14 by a larger epidemic in French Polynesia, south Pacific, where the first severe complications and non-vector-borne transmission of the virus were reported. Zika virus emerged in Brazil in 2015 and was declared a national public health emergency after local researchers and physicians reported an increase in microcephaly cases. In 2016, WHO declared the recent cluster of microcephaly cases and other neurological disorders reported in Brazil a global public health emergency. Similar clusters of microcephaly cases were also observed retrospectively in French Polynesia in 2014. In 2015-16, Zika virus continued its spread to cause outbreaks in the Americas and the Pacific, and the first outbreaks were reported in continental USA, Africa, and southeast Asia. Non-vector-borne transmission was confirmed and Zika virus was established as a cause of severe neurological complications in fetuses, neonates, and adults. This Review focuses on important updates and gaps in the knowledge of Zika virus as of early 2017.

Zika Virus Disease in Children in Colombia, August 2015 to May 2016

BACKGROUND

Children are considered a potentially vulnerable population for Zika virus infection. However, data on paediatric Zika virus infection are sparse.

METHODS

We analysed data from Colombia's national surveillance system during the 2015-2016 Zika virus outbreak on patients meeting the clinical case definition of Zika virus disease (ZVD) among children aged 1 month to 18 years to estimate incidence by demographic characteristics and characterize the occurrence of selected complications.

RESULTS

Between August 14, 2015, and May 28, 2016, there were 18 576 reported cases of postnatal ZVD among children aged 1 month to 18 years. Laboratory testing was prioritized for high-risk patients (infants, pregnant women, adults aged ≥65 years, and persons with serious co-morbidities); among 1655 that were tested by real-time reverse transcriptase polymerase chain reaction, 1207 (72.9%) were positive. The cumulative incidence of reported ZVD was 114.4 per 100 000. The incidence differed by sex, depending on age group; the largest difference was observed for 15-18 year olds, with females having a higher incidence than males (cumulative incidence ratio 2.5, 95% confidence interval 2.3, 2.7). At the time of report to the surveillance system, 631 patients (3.4%) were hospitalised and 96 (0.5%) had a report of an accompanying neurological diagnosis, including Guillain-Barré syndrome in 40 patients.

CONCLUSIONS

Only a small proportion of reported paediatric ZVD cases in Colombia were hospitalized or had reported neurological conditions following ZVD. However, the potential for some serious outcomes demonstrates the importance of preventing Zika virus infection in children.