Sero-molecular Prevalence of Zika Virus among Pregnant Women Attending Some Public Hospitals in Lagos State, Nigeria

Abstract

Zika virus (ZIKV) is one of the arboviruses implicated in febrile illness, microcephaly and other neurological disorders in babies whose mothers were infected during pregnancy. Information on ZIKV in Nigeria is limited. Hence, this study was aimed at investigating the seroprevalence of Zika virus among pregnant women in Lagos State. In a cross-sectional study, blood samples collected from 352 randomly selected pregnant women in four hospitals in Lagos State were separated and plasma analyzed using Zika virus IgG and IgM capture Enzyme-linked immunosorbent assay (Demeditec Diagnostics, Germany). The optical densities were read using Precision Microplate reader (Molecular devices) and cut-off calculated according to manufacturer’s guide. Parameters and symptoms such as history of fever, rashes on the body, exposure to mosquito were extracted from the questionnaire and analyzed. IgM seropositive samples were screened for ZIKV RNA on RT-qPCR. Out of 352 samples screened, 7(2.0%) and 5(1.4%) of the pregnant women tested positive for IgG and IgM respectively. None tested positive for both IgG and IgM markers. Statistical analysis showed that there is no significant relationship between the symptoms analyzed in this study at 95% Confidence interval except conjunctivitis. None of the ZIKV IgM seropositive samples tested positive for ZIKV RNA on RT-qPCR. The results show that there is evidence of exposure to Zika virus among the population studied in Lagos, Nigeria. Also, the low level seroprevalence of the virus in the population studied indicates that there is lack of herd immunity of Zika virus infection in Lagos, Nigeria.

Dengue and zika seropositivity, burden, endemicity, and cocirculation antibodies in Nigeria

“…Elsewhere, a seropositivity of 6.3% [ 1 ] was reported in the Columbia-Venezuela border, 2.6% [ 13 , 30–32 ] in Brazil and 1.7% [ 5 ] in Nicaragua. We also speculate from our findings in the three regions that antibody seropositivity against cocirculation is higher than currently perceived due to the rapid introduction of ZIKV in countries that are endemic for DENV [ 6 , 7 , 10–12 , 26 ].…”

“…In addition, 45.5%, 19.0%, and 5.4% of DENV seropositive, ZIKV seropositive, and DENV-ZIKV seropositive patients, respectively, were also positive for the malaria antigen. However, much lower seroprevalences have been reported elsewhere in Nigeria, most recently for dengue (34.7%, 9.4%, 10.1%, 18.0%) [ 8 , 9 , 15–25 ] and ZIKV (2.0%,12%) [ 6 , 7 , 10–12 , 26 ]. This confluence of heterogeneous findings could be explained by the common vector of transmission ( Aedes mosquito) [ 1–7 , 10–12 , 26–28 ] occurring in the three geographic areas simultaneously.…”

“…However, much lower seroprevalences have been reported elsewhere in Nigeria, most recently for dengue (34.7%, 9.4%, 10.1%, 18.0%) [ 8 , 9 , 15–25 ] and ZIKV (2.0%,12%) [ 6 , 7 , 10–12 , 26 ]. This confluence of heterogeneous findings could be explained by the common vector of transmission ( Aedes mosquito) [ 1–7 , 10–12 , 26–28 ] occurring in the three geographic areas simultaneously. The result might have also been influenced or shaped by DENV and ZIKV antibody cross-reactivity, past exposure to the arboviral vaccine (possibly yellow fever vaccine), and long-term exposure immunity.…”

“…It is likely that the different levels of endemicity (antibody seropositivity) against the two arboviruses in the three regions also resulted from different vector densities due to different vegetation types across the three regions, human population indices, climate changes (increasing reproductive activities and shortening the extrinsic cycle of arboviruses in vectors), vector adaptations, variations in temperature and humidity, and flooding (which favours the emergence and survival of arboviruses), which shape habitats and microclimates. Unplanned urbanization in the three regions favours mosquito-borne vector transmission dynamics [ 8 , 26 ]. Additionally, because of the limited testing capabilities of regional health systems to accurately diagnose arboviral infections and differentiate them from other febrile illnesses, this disease remains a hidden burden in various demographic groups as it is usually undetected by health services.…”

“…However, seropositive antibodies against ZIKV and DENV-ZIKV cocirculation were higher among single and divorced participants. This is not far from the fact that ZIKV is transmitted sexually [ 1–5 , 8 , 12 , 26–28 ]. There is also the possibility of overcrowding of families in major urban cities in the three regions, leading to a high burden on social services [ 8 , 9 , 15–25 ], which in turn contributes to high rates of DENV and ZIKV arboviral infection transmissibility.…”