Congenital heart defects in La Réunion Island: a 6-year survey within a EUROCAT-affiliated congenital anomalies registry.

OBJECTIVES: This study compares the prevalence and perinatal mortality of congenital heart defects on La Réunion with European (EUROCAT) standards. METHODS AND RESULTS: Data were extracted from a EUROCAT-affiliated congenital malformations registry, covering 88,025 births during the period 2002-2007, on the whole island territory. A total of 512 congenital heart defects were registered, including 424 live births, 18 foetal deaths from 16 weeks of gestation, and 70 terminations of pregnancy. The total prevalence of congenital heart defects was 5.8 per 1000 births and live birth prevalence was 4.8 per 1000. The total prevalence of non-chromosomal congenital heart defects was 5.1 per 1000 births, of which 3% were perinatal deaths, 33.3% prenatally diagnosed, and 11.6% termination of pregnancy. Severe non-chromosomal congenital heart defects - excluding ventricular septal defects, atrial septal defects, and pulmonary valve stenosis - occurred in 2.1 per 1000 births, of which 10.3% were perinatal deaths, 59.1% prenatally diagnosed, and 24.3% termination of pregnancy. Of the severe congenital heart defects, the rates of single ventricle (0.20‰), Ebstein anomaly (0.11‰), common arterial trunk (0.25‰), and atrioventricular septal defect (0.62‰) exceeded averages found in Europe, although coarctation of the aorta was infrequent. Conversely, rates of ventricular septal defects, atrial septal defects, and pulmonary valve stenosis were inferior to European standards. Slightly less than half of the congenital heart defects of chromosomal origin were associated with Down syndrome. CONCLUSION: In La Réunion, the total prevalence of congenital heart defects is far inferior to that found in Europe. The difference can be attributable to lower prevalences of mild congenital heart defects.

A mouse model for Chikungunya: young age and inefficient type-I interferon signaling are risk factors for severe disease.

Chikungunya virus (CHIKV) is a re-emerging arbovirus responsible for a massive outbreak currently afflicting the Indian Ocean region and India. Infection from CHIKV typically induces a mild disease in humans, characterized by fever, myalgia, arthralgia, and rash. Cases of severe CHIKV infection involving the central nervous system (CNS) have recently been described in neonates as well as in adults with underlying conditions. The pathophysiology of CHIKV infection and the basis for disease severity are unknown. To address these critical issues, we have developed an animal model of CHIKV infection. We show here that whereas wild type (WT) adult mice are resistant to CHIKV infection, WT mouse neonates are susceptible and neonatal disease severity is age-dependent. Adult mice with a partially (IFN-alpha/betaR(+/-)) or totally (IFN-alpha/betaR(-/-)) abrogated type-I IFN pathway develop a mild or severe infection, respectively. In mice with a mild infection, after a burst of viral replication in the liver, CHIKV primarily targets muscle, joint, and skin fibroblasts, a cell and tissue tropism similar to that observed in biopsy samples of CHIKV-infected humans. In case of severe infections, CHIKV also disseminates to other tissues including the CNS, where it specifically targets the choroid plexuses and the leptomeninges. Together, these data indicate that CHIKV-associated symptoms match viral tissue and cell tropisms, and demonstrate that the fibroblast is a predominant target cell of CHIKV. These data also identify the neonatal phase and inefficient type-I IFN signaling as risk factors for severe CHIKV-associated disease. The development of a permissive small animal model will expedite the testing of future vaccines and therapeutic candidates.

Multidisciplinary prospective study of mother-to-child chikungunya virus infections on the island of La Réunion.

BACKGROUND: An outbreak of chikungunya virus affected over one-third of the population of La Réunion Island between March 2005 and December 2006. In June 2005, we identified the first case of mother-to-child chikungunya virus transmission at the Groupe Hospitalier Sud-Réunion level-3 maternity department. The goal of this prospective study was to characterize the epidemiological, clinical, biological, and radiological features and outcomes of all the cases of vertically transmitted chikungunya infections recorded at our institution during this outbreak. METHODS AND FINDINGS: Over 22 mo, 7,504 women delivered 7,629 viable neonates; 678 (9.0%) of these parturient women were infected (positive RT-PCR or IgM serology) during antepartum, and 61 (0.8%) in pre- or intrapartum. With the exception of three early fetal deaths, vertical transmission was exclusively observed in near-term deliveries (median duration of gestation: 38 wk, range 35-40 wk) in the context of intrapartum viremia (19 cases of vertical transmission out of 39 women with intrapartum viremia, prevalence rate 0.25%, vertical transmission rate 48.7%). Cesarean section had no protective effect on transmission. All infected neonates were asymptomatic at birth, and median onset of neonatal disease was 4 d (range 3-7 d). Pain, prostration, and fever were present in 100% of cases and thrombocytopenia in 89%. Severe illness was observed in ten cases (52.6%) and mainly consisted of encephalopathy (n = 9; 90%). These nine children had pathologic MRI findings (brain swelling, n = 9; cerebral hemorrhages, n = 2), and four evolved towards persistent disabilities. CONCLUSIONS: Mother-to-child chikungunya virus transmission is frequent in the context of intrapartum maternal viremia, and often leads to severe neonatal infection. Chikungunya represents a substantial risk for neonates born to viremic parturients that should be taken into account by clinicians and public health authorities in the event of a chikungunya outbreak.

[Early maternal-fetal transmission of the Chikungunya virus]. / Transmission materno-foetale précoce du virus Chikungunya.

INTRODUCTION: Since the onset of the Chikungunya outbreak in Reunion Island, vertical maternal-fetal transmission of the virus has been observed in newborns, but no such transmission has been demonstrated early during pregnancy. We report here the first three cases of maternal-fetal transmission of the Chikungunya virus (CHIKV) before 16 weeks' gestational age. CASES: Maternal infections occurred at terms of 12 weeks and 4 days, 15 weeks and 5 days, and 15 weeks and were confirmed by positive findings for specific anti-CHIKV IgM. Fetal deaths were subsequently observed, and at that point, CHIKV RT-PCR was negative for all three maternal blood samples. Amniocentesis preceded rupture of membranes in all three cases. RT-PCR showed viral genome in the amniotic fluid of the three fetuses, in the placentas of two, and in the brains of two. Autopsy found no malformations, and all other bacterial and viral test results were negative. DISCUSSION: These findings demonstrate early maternal-fetal transmission of CHIKV, which is suspected to be directly linked to the fetal deaths. This vertical transmission, probably abortifacient, should be considered in the light of human and animal responses to other arboviruses.