[Chikungunya infection in pregnancy: Evidence for intrauterine infection in pregnant women and vertical transmission in the parturient. Survey of the Reunion Island outbreak].

PURPOSE: Since February 2005, an outbreak of Chikungunya virus (CHIKV) infections occurred in Reunion Island. It is transmitted by the Aedes albopictus mosquito. Neonatal cases observations suggest possible fetal transmission during pregnancy. MATERIAL [corrected] AND METHODS. Observations made in 160 pregnant mothers infected by CHIKV between June 1, 2005 and February 28, 2006, in the south of Reunion island were recorded.

RESULTS: Three of nine miscarriages before 22 weeks of gestation could be attributed to the virus. 3,829 births took place during this time. Among the 151 infected women, 118 were viremia negative at delivery, and none of the newborns showed any damage. Among the 33 with positive viremia at delivery, 16 newborns (48.5%) presented neonatal Chikungunya.

DISCUSSION: Though fetal contamination risks appear to be rare before 22 weeks of gestation, they are potentially dangerous. After 22 weeks gestation, newborns infection occurs if the mother is viremia positive at delivery. Transplacental transmission is suspected, but the pathogenic mechanism remains unknown.