Arboviruses and pregnancy: maternal, fetal, and neonatal effects

Insect vectors endosymbionts as solutions against diseases

Viral diseases transmitted by mosquitoes, known as arboviruses, pose a significant threat to human life and are a major burden on many health systems around the world. Currently, arbovirus control strategies rely on insecticides or vector source reduction and, in the absence of effective, accessible and affordable vaccines, mainly on symptomatic based, non-specific treatments. However, insecticides have the potential to interfere with non-target organisms, cause environmental toxicity and insecticide resistance reduces their effectiveness as a sustainable control method. Complementary and sustainable strategies are urgently needed. Wolbachia, an invertebrate endosymbiont, has been used as an alternative strategy for arboviral control, through suppression or modification of mosquito populations. Here we discuss the burden that arboviruses impose on human populations and how Wolbachia can be used as a sustainable strategy for control, in alignment with the United Nations- 2030 Agenda for Sustainable Development.

Epidemic Alphaviruses: Ecology, Emergence and Outbreaks

Over the past century, the emergence/reemergence of arthropod-borne zoonotic agents has been a growing public health concern. In particular, agents from the genus Alphavirus pose a significant risk to both animal and human health. Human alphaviral disease presents with either arthritogenic or encephalitic manifestations and is associated with significant morbidity and/or mortality. Unfortunately, there are presently no vaccines or antiviral measures approved for human use. The present review examines the ecology, epidemiology, disease, past outbreaks, and potential to cause contemporary outbreaks for several alphavirus pathogens.

Global Perspectives on Immunization During Pregnancy and Priorities for Future Research and Development: An International Consensus Statement

Immunization during pregnancy has been recommended in an increasing number of countries. The aim of this strategy is to protect pregnant women and infants from severe infectious disease, morbidity and mortality and is currently limited to tetanus, inactivated influenza, and pertussis-containing vaccines. There have been recent advancements in the development of vaccines designed primarily for use in pregnant women (respiratory syncytial virus and group B Streptococcus vaccines). Although there is increasing evidence to support vaccination in pregnancy, important gaps in knowledge still exist and need to be addressed by future studies. This collaborative consensus paper provides a review of the current literature on immunization during pregnancy and highlights the gaps in knowledge and a consensus of priorities for future research initiatives, in order to optimize protection for both the mother and the infant.

Tick-borne encephalitis virus (TBEV) infection in pregnancy: Absence of virus transmission to the fetuses despite severe maternal disease - A case study

Tick-borne encephalitis (TBE) is an emerging infectious disease in large parts of Europe and Asia. Whereas other members of the Flaviviridae family can harm fetal development, there are only very few reports on TBE virus (TBEV) infections during pregnancy. Thus, the implications for fetal health remain largely unknown. In this study, we present detailed pre- and postnatal health assessment of three children in the context of severe maternal TBEV infection during pregnancy. Following acute TBEV infection of the mothers, intrauterine growth and development of all children were assessed by repetitive prenatal ultrasound. Postnatal examinations included clinical and virological analyses over a follow-up period of 18 months. Prenatally, no signs of intrauterine growth restrictions were observed. All neonates were delivered at term. Umbilical cord blood of the newborns tested negative for TBEV RNA. Virus-specific IgG antibodies were positive at birth but negative at 9 and 11 months of age. Importantly, IgM antibodies remained negative throughout the period of observation. Taken together, these clinical and virological data strongly suggest that fetal TBEV infection did not occur, despite severe manifestations in the mothers.

Yellow Fever Vaccine Safety Perception of Pregnant Women in Emergency Response Mass Vaccination in Uganda

Yellow fever vaccine, a live attenuated vaccine, is primarily administered to pregnant women during outbreaks. A qualitative study was conducted in pregnant women on the perception of yellow fever mass vaccination. In total, interviews with 20 women-13 semi-structured interviews and one focus group discussion with seven participants-were analyzed. This study showed that conflicting information about vaccine safety led to concern about miscarriage. Furthermore, it was believed that vaccination during gestation would concurrently immunize the fetus by transplacental antibody transfer. Consultation of health workers at the vaccination site led to diverse recommendations. When vaccinating pregnant women, clear health communication is crucial. Vaccine recommendations should be obeyed, and health workers should be trained to address emerging vaccine concerns. Pregnant women should be informed that a booster dose is recommended to achieve lifelong immunity. After pregnancy, a booster should be offered to women in endemic areas.

Arboviral diseases in pediatrics

OBJECTIVES

To present the currently available evidence on transmission, clinical, diagnostic methods, treatment, and prevention methods of major arboviruses that occur in childhood.

SOURCE OF DATA

Non-systematic review carried out in MEDLINE (PubMed), LILACS (VHL), Scopus, Web of Science, Cochrane, CAPES Portal, and Google Scholar databases for the past five years using the search terms arboviruses, dengue, chikungunya, Zika, Mayaro, and West Nile fever, as well as child, newborn, and adolescent.

SYNTHESIS OF DATA

The main characteristic of arboviruses is the fact that part of their replication cycle occurs inside insect vectors, thus being classically transmitted to humans through the bite of mosquitoes (hematophagous arthropods), although non-vector transmission of these viruses is also possible in specific situations. These diseases remain a major public health challenge, due to the lack of specific antiviral treatment, the co-circulation of different arboviruses in endemic/epidemic regions, the lack of effective and safe immunizations for the vast majority of these viruses, and the great difficulty in vector control, especially in large urban centers.

CONCLUSIONS

Children are especially vulnerable to this group of diseases due to characteristics that facilitate the development of the most severe forms. More detailed knowledge of this group of diseases allows the pediatrician to diagnose them earlier, implement the correct treatment, monitor warning signs for the most severe forms, and establish effective preventive measures.

Antibodies for Venezuelan Equine Encephalitis Virus Protect Embryoid Bodies from Chikungunya Virus

Chikungunya virus (CHIKV) is an alphavirus that causes febrile illness punctuated by severe polyarthralgia. After the emergence of CHIKV in the Western Hemisphere, multiple reports of congenital infections were published that documented neurological complications, cardiac defects, respiratory distress, and miscarriage. The Western Hemisphere is endemic to several alphaviruses, and whether antigenic cross-reactivity can impact the course of infection has not been explored. Recent advances in biomedical engineering have produced cell co-culture models that replicate the cellular interface at the maternal fetal axis. We employed a trans-well assay to determine if cross-reactive antibodies affected the movement and replication of CHIKV across placental cells and into an embryoid body. The data showed that antibodies to Venezuelan equine encephalitis virus significantly reduced CHIKV viral load in embryoid bodies. The data highlighted the fact that viral pathogenesis can be cell-specific and that exploiting antigenic cross-reactivity could be an avenue for reducing the impact of congenital CHIKV infections.

From Ancient to Emerging Infections: The Odyssey of Viruses in the Male Genital Tract

The male genital tract (MGT) is the target of a number of viral infections that can have deleterious consequences at the individual, offspring, and population levels. These consequences include infertility, cancers of male organs, transmission to the embryo/fetal development abnormalities, and sexual dissemination of major viral pathogens such as human immunodeficiency virus (HIV) and hepatitis B virus. Lately, two emerging viruses, Zika and Ebola, have additionally revealed that the human MGT can constitute a reservoir for viruses cleared from peripheral circulation by the immune system, leading to their sexual transmission by cured men. This represents a concern for future epidemics and further underlines the need for a better understanding of the interplay between viruses and the MGT. We review here how viruses, from ancient viruses that integrated the germline during evolution through old viruses (e.g., papillomaviruses originating from Neanderthals) and more modern sexually transmitted infections (e.g., simian zoonotic HIV) to emerging viruses (e.g., Ebola and Zika) take advantage of genital tract colonization for horizontal dissemination, viral persistence, vertical transmission, and endogenization. The MGT immune responses to viruses and the impact of these infections are discussed. We summarize the latest data regarding the sources of viruses in semen and the complex role of this body fluid in sexual transmission. Finally, we introduce key animal findings that are relevant for our understanding of viral infection and persistence in the human MGT and suggest future research directions.

Dengue, Zika and chikungunya during pregnancy: pre- and post-travel advice and clinical management

RATIONALE FOR REVIEW

Young adults of childbearing age and pregnant women are travelling more frequently to tropical areas, exposing them to specific arboviral infections such as dengue, zika and chikungunya viruses, which may impact ongoing and future pregnancies. In this narrative review, we analyse their potential consequences on pregnancy outcomes and discuss current travel recommendations.

MAIN FINDINGS

Dengue virus may be associated with severe maternal complications, particularly post-partum haemorrhage. Its association with adverse fetal outcomes remains unclear, but prematurity, growth retardation and stillbirths may occur, particularly in cases of severe maternal infection. Zika virus is a teratogenic infectious agent associated with severe brain lesions, with similar risks to other well-known TORCH pathogens. Implications of chikungunya virus in pregnancy are mostly related to intrapartum transmission that may be associated with severe neonatal infections and long-term morbidity.

TRAVEL RECOMMENDATIONS

Few agencies provide specific travel recommendations for travelling pregnant patients or couples trying to conceive and discrepancies exist, particularly regarding Zika virus prevention. The risks significantly depend on epidemiological factors that may be difficult to predict. Prevention relies principally on mosquito control measures. Couples trying to conceive and pregnant women should receive adequate information about the potential risks. It seems reasonable to advise pregnant women to avoid unnecessary travel to Aedes spp. endemic regions. The current rationale to avoid travel and delay conception is debatable in the absence of any epidemic. Post-travel laboratory testing should be reserved for symptomatic patients.

Maternal Zika Virus Infection: Association With Small-for-Gestational-Age Neonates and Preterm Birth

OBJECTIVE

To evaluate whether antenatal Zika virus infection is associated with risk of having a small-for-gestational-age (SGA) neonate, risk of preterm birth, and lower mean birth weight of term neonates.

METHODS

For this retrospective observational study, we linked birth record data for women who delivered liveborn singleton neonates in New York City in 2016 to data for pregnant women with Zika virus infection reported to the New York City Health Department. We restricted the analysis to nonsmoking, nonwhite women and adjusted for maternal characteristics. Among women with antenatal Zika virus infection, we used modified Poisson regression to assess risks of having an SGA neonate and of delivering preterm, and linear regression to assess the association of infection with mean birth weight of term neonates.

RESULTS

Of 116,034 deliveries of singleton neonates in New York City in 2016, 251 (0.2%) were to women with antenatal Zika virus infection. A higher percentage of women with Zika virus infection delivered an SGA neonate compared with those without (11.2% vs 5.8%; adjusted relative risk [RR] 1.8; 95% CI 1.3-2.6). There was no difference in preterm birth prevalence for women with and without Zika virus infection (adjusted RR 1.0; 95% CI 0.69-1.6). Mean birth weight of term neonates born to women with Zika virus infection was 47 g less (95% CI -105 to 11 g); this difference was not statistically significant in crude or adjusted analyses.

CONCLUSION

For a cohort of New York City women, antenatal Zika virus infection was associated with an increased risk of having an SGA neonate, but not preterm birth or lower mean birth weight of term neonates. This supports a putative association between Zika virus infection during pregnancy and SGA.

Pityriasis rosea and other infectious eruptions during pregnancy: Possible life-threatening health conditions for the fetus

Any infectious illness presenting with an eruption in a pregnant patient may be associated with an increased risk of fetal loss. The viruses that can infect the placenta during maternal infection and can be transmitted to the fetus and cause congenital disease include the rubella virus, the measles virus, the varicella zoster virus, parvovirus B19, human cytomegalovirus, arboviruses, and hepatitis E virus type 1. In addition, some bacteria responsible for exanthematous diseases, like Treponema pallidum, can be transmitted during pregnancy from the mother to the fetus and cause fetal loss. All these infectious agents can cause typical and/or atypical exanthems whose etiologic diagnosis is sometimes difficult but important to determine, especially in pregnant women because of the potential risk to the fetus. In the last 20 years, we have extensively studied pityriasis rosea from the clinical and laboratory perspectives, demonstrating the pathogenic role of human herpesvirus (HHV)-6 and -7. We synthesize the available evidence that PR may be associated with active HHV-6/7 infection and therefore with complications during pregnancy and fetal loss. We have also summarized the emerging infectious illnesses of dermatologic interest that may represent life-threatening health conditions for the fetus: measles, rubella, arbovirus infection, and syphilis.

Clinical features and virological confirmation of perinatal dengue infection in Jambi, Indonesia: A case report

The hyper-endemicity of dengue in Indonesia poses a significant threat of dengue virus (DENV) vertical transmission during pregnancy. A 29-year-old female at 38 weeks of pregnancy presented to hospital with acute fever and later confirmed with DENV infection. Due to signs of fetal distress, the neonate was delivered by emergency caesarean section. The mother developed a dengue critical phase post-caesarean with excessive bleeding and required blood transfusion. During the 6th day of life, the neonate was diagnosed and later confirmed with dengue. Next-generation sequencing of DENV RNA isolated directly from sera of both mother and neonate revealed identical DENV-2 whole-genome sequences. Plaque reduction neutralization test (PRNT) detected anti-dengue antibodies in both mother and neonate. Altogether, our data confirmed the occurrence of vertical transmission. Dengue vertical transmission during pregnancy may lead to severe manifestation, hence early diagnosis, close monitoring, and prompt intervention are critical.

Dengue and Zika Virus Diagnostic Testing for Patients with a Clinically Compatible Illness and Risk for Infection with Both Viruses

Dengue and Zika viruses are closely related mosquitoborne flaviviruses with similar transmission cycles, distribution throughout the tropics and subtropics, and disease manifestations including fever, rash, myalgia, and arthralgia. For patients with suspected dengue or Zika virus disease, nucleic acid amplification tests (NAATs) are the preferred method of diagnosis. Immunoglobulin M (IgM) antibody testing can identify additional infections and remains an important tool for the diagnosis of these diseases, but interpreting the results is complicated by cross-reactivity, and determining the specific timing of infection can be difficult. These limitations are a particular challenge for pregnant women in determining whether Zika virus infection occurred during or before the pregnancy.

This report summarizes existing and new guidance on dengue and Zika virus diagnostic testing for patients with a clinically compatible illness who live in or recently traveled to an area where there is risk for infection with both viruses. CDC recommendations for screening of asymptomatic pregnant women with possible Zika virus exposure are unchanged. For symptomatic nonpregnant persons, dengue and Zika virus NAATs should be performed on serum collected ≤7 days after symptom onset. Dengue and Zika virus IgM antibody testing should be performed on NAAT-negative serum specimens or serum collected >7 days after onset of symptoms. For symptomatic pregnant women, serum and urine specimens should be collected as soon as possible within 12 weeks of symptom onset for concurrent dengue and Zika virus NAATs and IgM antibody testing. Positive IgM antibody test results with negative NAAT results should be confirmed by neutralizing antibody tests when clinically or epidemiologically indicated, including for all pregnant women. Data on the epidemiology of viruses known to be circulating at the location of exposure and clinical findings should be considered when deciding which tests to perform and for interpreting results.

Patients with clinically suspected dengue should receive appropriate management to monitor and treat shock and hemorrhage. Women with laboratory evidence of possible Zika virus infection during pregnancy and their infants should be evaluated and managed for possible adverse outcomes. Dengue and Zika virus disease are nationally notifiable conditions, and cases should be reported to public health authorities.

Vertically transmitted chikungunya, Zika and dengue virus infections: The pathogenesis from mother to fetus and the implications of co-infections and vaccine development

Chikungunya (CHIKV), Zika (ZIKV), and Dengue viruses (DENV) exhibit similar epidemiological and clinical patterns but have different pathophysiological mechanisms of disease manifestations. Differences occur in the severity of clinical presentations with the highest mortality in the general population attributed to DENV and neurological morbidity due to ZIKV. ZIKV and DENV infections can cause fetal loss with ZIKV exhibiting teratogenesis. CHIKV is associated with severe complications in the newborn. Co-circulation of the three viruses and the cross-reactive immune response between ZIKV and DENV viruses has implications for an attenuated clinical response and future vaccine development. Co-infections could increase due to the epidemiologic synergy, but there is limited evidence about the clinical effects, especially for the vulnerable newborn. The purpose of this paper is to review the pathophysiological basis for vertically transmission manifestations due to CHIKV, DENV, and ZIKV, to determine the potential effects of co-circulation on newborn outcomes and the potential for vaccine protection. Inflammatory cytokines are responsible for placental breaches in DENV and ZIKV; Hofbauer cells facilitate the transfer of ZIKV from the placenta to the fetal brain, and high viral loads and mechanical placental disruption facilitate the transmission of CHIKV. Co-infection of these viruses can present with severe manifestations, but the clinical and serologic evidence suggests that one virus predominates which may influence fetal transmission. All three viruses are in different stages of vaccine development with DENV vaccine being fully licensed. Antibody-enhanced infections in seronegative vaccinated candidates who develop natural infection to dengue limit its use and have implications for ZIKV vaccine development. Targeting transmission capacity in the vector could prevent transmission to all three viruses, and breast milk immunity could provide further clues for vaccine development.

Atovaquone Inhibits Arbovirus Replication through the Depletion of Intracellular Nucleotides

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

The Unfolded Protein Response: A Key Player in Zika Virus-Associated Congenital Microcephaly

Zika virus (ZIKV) is a mosquito-borne virus that belongs to the Flaviviridae family, together with dengue, yellow fever, and West Nile viruses. In the wake of its emergence in the French Polynesia and in the Americas, ZIKV has been shown to cause congenital microcephaly. It is the first arbovirus which has been proven to be teratogenic and sexually transmissible. Confronted with this major public health challenge, the scientific and medical communities teamed up to precisely characterize the clinical features of congenital ZIKV syndrome and its underlying pathophysiological mechanisms. This review focuses on the critical impact of the unfolded protein response (UPR) on ZIKV-associated congenital microcephaly. ZIKV infection of cortical neuron progenitors leads to high endoplasmic reticulum (ER) stress. This results in both the stalling of indirect neurogenesis, and UPR-dependent neuronal apoptotic death, and leads to cortical microcephaly. In line with these results, the administration of molecules inhibiting UPR prevents ZIKV-induced cortical microcephaly. The discovery of the link between ZIKV infection and UPR activation has a broader relevance, since this pathway plays a crucial role in many distinct cellular processes and its induction by ZIKV may account for several reported ZIKV-associated defects.

Tropism of the Chikungunya Virus

Chikungunya virus (CHIKV) is a re-emerging mosquito-borne virus that displays a large cell and organ tropism, and causes a broad range of clinical symptoms in humans. It is maintained in nature through both urban and sylvatic cycles, involving mosquito vectors and human or vertebrate animal hosts. Although CHIKV was first isolated in 1953, its pathogenesis was only more extensively studied after its re-emergence in 2004. The unexpected spread of CHIKV to novel tropical and non-tropical areas, in some instances driven by newly competent vectors, evidenced the vulnerability of new territories to this infectious agent and its associated diseases. The comprehension of the exact CHIKV target cells and organs, mechanisms of pathogenesis, and spectrum of both competitive vectors and animal hosts is pivotal for the design of effective therapeutic strategies, vector control measures, and eradication actions.

Chikungunya Virus Vaccines: Platforms, Progress, and Challenges

Chikungunya is a clinically and economically important arbovirus that has spread globally in the twenty-first century. While uncommonly fatal, infection with the virus can lead to incapacitating arthralgia that can persist for months to years. The adverse impacts of viral spread are most severe in developing low- and middle-income countries in which medical infrastructure is insufficient and manual labor is an economic driver. Unfortunately, no prophylactic or therapeutic treatments are approved for human use to combat the virus. Historically, vaccination has proven to be the most efficient and successful strategy for protecting populations and eradicating infectious disease. A large and diverse range of promising vaccination approaches for use against Chikungunya has emerged in recent years and been shown to safely elicit protective immune responses in animal models and humans. Importantly, many of these are based on technologies that have been clinically approved for use against other pathogens. Furthermore, clinical trials are currently ongoing for a subset of these. The purpose of this review is to provide a description of the relevant immunobiology of Chikungunya infection, to present immune-stimulating technologies that have been successfully employed to protect against infection, and discuss priorities and challenges regarding the future development of a vaccine for clinical use.

Arboviruses in pregnancy: consequences of maternal and fetal infection

Epidemics and localised outbreaks of infections due to arthropod borne (arbo) viruses, have been described for hundreds of years. Few viruses to date are known to transmit from mother to fetus, causing either teratogenic effects or fetal demise (see recent reviews Charlier et al.1 and Marinho et al.2). Many arboviruses are zoonotic but there appear to be few parallels between the effect of these viruses following human or animal infection during pregnancy. Higher rates of MTCT (mother to child transmission) may be seen (1) where herd immunity is reduced, either because virus is newly introduced into a population (as occurred in Brazil with ZIKV), or where the virus has only recently become endemic (as occurred with West Nile virus (WNV) in the USA in the 1990s), (2) where the arthropod vector is present, (3) where the vector transmits virus efficiently, and (4) in groups of pregnant women exposed, allowing transmission3.