Zika virus infections and associated risk factors among pregnant women in Gombe, Nigeria.

In-utero exposure to Zika virus (ZIKV) could lead to miscarriage, preterm birth and congenital Zika syndrome. This study aimed at estimating the burden of ZIKV and Dengue virus (DENV) infections among pregnant women in Bojude, Nigeria. A total of 200 blood samples were collected from pregnant women between February and April 2022. Using the updated CDC guidelines for the diagnosis of ZIKV infections, including ELISA and microneutralization test (MNT), we found that 16.5% of participants were positive for ZIKV IgM, 10% were positive for IgG, and 23% had nAb in their serum. Among the 46 ZIKV nAb-positive women, 52.2% and 10.9% were recent and previous ZIKV infections, respectively, while 6.5% had previous DENV infections. Although no recent DENV infection was detected, recent and previous ZIKV/DENV co-infections were 13.0% and 17.4%, respectively. Two participants had recent secondary ZIKV infections, while 39.1% had prolonged lifelong immunity. Recent ZIKV infection rates were significantly higher among sexually active females aged 20-29 years than other age groups, with the highest risk observed in the first trimester of pregnancy. In addition, the grand-multiparous women are at higher risk of ZIKV infections than other categories. Monotypic recent, secondary and past ZIKV infections, as well as DENV and ZIKV co-infections, were detected in both the asymptomatic and symptomatic pregnant women. These findings highlight that ZIKV infection is prevalent among pregnant women in Nigeria and underscore the associated risk factors, providing evidence-based information on the burden of ZIKV infections in DENV-endemic region.