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 children with congenital Zika syndrome. This study aimed at estimating the burden of ZIKV infection among pregnant women from 21 Feb and 19 April 2022. ELISA and microneutralization test (MNT) were used to detect the presence of ZIKV antibodies. All the ZIKV IgM positive samples were retested for dengue virus (DENV) and ZIKV RNA, and DENV NS1 antigen. Additionally, all the samples with ZIKV neutralizing antibody (nAb) were retested for DENV antigen, antibody and nucleic acid. Of 200 pregnant women, 16.5% were positive for ZIKV IgM, 10% were positive for IgG, and 23% were found to have 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 against the virus. Recent ZIKV infection rates were significantly higher among sexually active females aged 20-29 years than other age groups and women who had no pre-knowledge of the virus. ZIKV infection is not significantly associated with early and late trimester, but the risk of ZIKV infection is highest in the women in first trimester of pregnancy. The grand-multiparous women are at higher risk of ZIKV infections than other categories. In addition, women with and without a history of children with paralysis, brain defects (microcephaly) and stillbirths (claimed by the women) had both recent and past ZIKV infections. Monotypic recent, secondary and past ZIKV and co-infections with DENV and ZIKV were detected among the asymptomatic and symptomatic pregnant women.