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.