Chikungunya virus antepartum transmission and abnormal infant outcomes in Nigeria.

Chikungunya virus (CHIKV) has become a global public health concern since the reemergence of the Indian Ocean lineage and expansion of the Asian genotype. CHIKV infection causes acute febrile illness, rash, and arthralgia and during pregnancy may affect both mothers and infants. The mother-to-child transmission (MTCT) of CHIKV in Africa remains understudied. We screened 1006 pregnant women at two clinics in Nigeria between 2019 and 2022 and investigated the prevalence and MTCT of CHIKV. Of the 1006, 119 tested positive for CHIKV IgM, of which 36 underwent detailed laboratory tests. While none of the IgM reactive samples were RT-PCR positive, 14 symptomatic pregnant women were confirmed by CHIKV neutralization test. Twelve babies were followed with 8 normal and 4 abnormal outcomes, including stillbirth, cleft lip/palate with microcephaly, preterm delivery, polydactyly with sepsis and jaundice. CHIKV IgM testing identified 3 antepartum transmissions, further studies will determine its impact in antepartum infection.