Reassessment of the risk of birth defects due to Zika virus in Guadeloupe, 2016

[Zika virus infection: sexual transmission and implications for prevention]

Zika virus infection, most oft n responsible for a benign arboviral disease or an asymptomatic infection, rarely Guillain-Barré syndrome, can become problematic in pregnant women, due to a risk of fetal malformations, in particular microcephaly linked to its neurotropism. The most recent large-scale epidemic was observed throughout Latin America between 2015 and 2017, causing several hundred thousand cases. Transmission is predominantly vector-borne, but sexual transmission has been described, mainly among travelers, although it undoubtedly accounts for a significant proportion of transmission in epidemic areas. The aim of this review is to describe this sexual transmission, mainly through examples linked to this large-scale epidemic in Latin America, to describe the link with prolonged excretion of infectious viral particles in genital secretions, especially semen but also vaginal secretions, and to highlight possible preventive measures apart from vector transmission, in particular the need for pregnant women or women wishing to become pregnant to avoid visiting countries where circulation of Zika virus is described.

Arboviral Risk Associated with Solid Organ and Hematopoietic Stem Cell Grafts: The Prophylactic Answers Proposed by the French High Council of Public Health in a National Context

Diseases caused by arboviruses are on the increase worldwide. In addition to arthropod bites, most arboviruses can be transmitted via accessory routes. Products of human origin (labile blood products, solid organs, hematopoietic stem cells, tissues) present a risk of contamination for the recipient if the donation is made when the donor is viremic. Mainland France and its overseas territories are exposed to a complex array of imported and endemic arboviruses, which differ according to their respective location. This narrative review describes the risks of acquiring certain arboviral diseases from human products, mainly solid organs and hematopoietic stem cells, in the French context. The main risks considered in this study are infections by West Nile virus, dengue virus, and tick-borne encephalitis virus. The ancillary risks represented by Usutu virus infection, chikungunya, and Zika are also addressed more briefly. For each disease, the guidelines issued by the French High Council of Public Health, which is responsible for mitigating the risks associated with products of human origin and for supporting public health policy decisions, are briefly outlined. This review highlights the need for a "One Health" approach and to standardize recommendations at the international level in areas with the same viral epidemiology.

Consequences of In Utero Zika Virus Exposure and Adverse Pregnancy and Early Childhood Outcomes: A Prospective Cohort Study

We aimed to describe adverse pregnancy outcomes among women who had symptomatic, RT-PCR-confirmed ZIKV infection and early childhood outcomes among their infants. We enrolled pregnant women with symptomatic, RT-PCR-confirmed ZIKV infection in a prospective cohort study, and their infants in a prospective pediatric cohort study. We defined adverse pregnancy and early childhood outcomes based on selected neurologic, ophthalmologic, auditory, musculoskeletal, and anthropometric abnormalities. We used RT-PCR and serologic tests to determine the ZIKV infection status of the child. Between 10 March and 24 November 2016, we enrolled 546 pregnant women with RT-PCR-confirmed ZIKV infection. The overall risk of adverse pregnancy and early childhood outcomes possibly related to in utero ZIKV exposure was 15.7% (95% CI: 12.8-19.0), distributed as follows: 3.6% (95% CI: 2.3-5.6) severe sequelae or fatality; 2.7% (95% CI: 1.6-4.5) major abnormalities; 9.4% (95% CI:7.1-12.2) mild abnormalities. The risk of severe sequelae or fatality was higher when ZIKV infection occurred during the first trimester (7.0%), compared to the second (2.7%) or third trimester (1.4%) (p = 0.02). Among the infants for whom ZIKV infection status could be determined, the vertical transmission rate was 3.0% (5/167) (95% CI: 1.1-7.2). Among pregnant women with symptomatic, RT-PCR-confirmed ZIKV infection, severe or major pregnancy or early childhood outcomes were present in 6.3% of fetuses and infants. Severe outcomes occurred more frequently in fetuses and infants whose mothers had been infected in the first trimester.

Transplacental Zika virus transmission in ex vivo perfused human placentas

A Zika virus (ZIKV) infection during pregnancy can result in severe birth defects such as microcephaly. To date, it is incompletely understood how ZIKV can cross the human placenta. Furthermore, results from studies in pregnant mice and non-human primates are conflicting regarding the role of cross-reactive dengue virus (DENV) antibodies on transplacental ZIKV transmission. Elucidating how ZIKV can cross the placenta and which risk factors contribute to this is important for risk assessment and for potential intervention strategies for transplacental ZIKV transmission. In this study we use an ex vivo human placental perfusion model to study transplacental ZIKV transmission and the effect that cross-reactive DENV antibodies have on this transmission. By using this model, we demonstrate that DENV antibodies significantly increase ZIKV uptake in perfused human placentas and that this increased uptake is neonatal Fc-receptor-dependent. Furthermore, we show that cross-reactive DENV antibodies enhance ZIKV infection in term human placental explants and in primary fetal macrophages but not in primary trophoblasts. Our data supports the hypothesis that presence of cross-reactive DENV antibodies could be an important risk factor for transplacental ZIKV transmission. Furthermore, we demonstrate that the ex vivo placental perfusion model is a relevant and animal friendly model to study transplacental pathogen transmission.

Zika virus is a mosquito-transmitted virus that can cause severe birth defects such as microcephaly when the infection occurs during pregnancy. Understanding how Zika virus crosses the placenta during pregnancy is important for future prevention strategies for vertical Zika virus transmission. Despite significant efforts to study this, to date it remains incompletely understood how Zika virus can cross the placenta and which risk factors contribute to this form of transmission. In this study we use an ex vivo placental perfusion model to study transplacental Zika virus transmission. The ex vivo placental perfusion model is a highly physiological and animal friendly model that mimics the in vivo conditions during pregnancy. We found that antibodies against the closely related dengue virus can significantly enhance placental uptake of Zika virus and Zika virus infection of human placental explants and fetal macrophages. These findings indicate that presence of cross-reactive dengue virus antibodies could contribute to transplacental Zika virus transmission.