Surveillance of the major pathogenic arboviruses of public health concern in Gabon, Central Africa: increased risk of West Nile virus and dengue virus infections

Yuri Ushijima,Rodrigue Bikangui,Bertrand Lell,Joseph G E Essimengane,Jiro Yasuda,Emmanuel B Bache,Selidji T Agnandji,Vahid R Zadeh,Haruka Abe,Marguerite Massinga Loembé,Georgelin Nguema Ondo,Armel V N Mbouna

doi:10.1186/s12879-021-05960-9

Abstract

BackgroundIncreasing arbovirus infections have been a global burden in recent decades. Many countries have experienced the periodic emergence of arbovirus diseases. However, information on the prevalence of arboviruses is largely unknown or infrequently updated because of the lack of surveillance studies, especially in Africa.MethodsA surveillance study was conducted in Gabon, Central Africa, on arboviruses, which are a major public health concern in Africa, including: West Nile virus (WNV), dengue virus (DENV), Zika virus (ZIKV), yellow fever virus (YFV), chikungunya virus (CHIKV), and Rift Valley fever virus (RVFV). Serological and molecular assays were performed to investigate past infection history and the current status of infection, using serum samples collected from healthy individuals and febrile patients, respectively.ResultsThe overall seroprevalence during 2014˗2017 was estimated to be 25.3% for WNV, 20.4% for DENV, 40.3% for ZIKV, 60.7% for YFV, 61.2% for CHIKV, and 14.3% for RVFV. No significant differences were found in the seroprevalence of any of the viruses between the male and female populations. However, a focus on the mean age in each arbovirus-seropositive individual showed a significantly younger age in WNV- and DENV-seropositive individuals than in CHIKV-seropositive individuals, indicating that WNV and DENV caused a relatively recent epidemic in the region, whereas CHIKV had actively circulated before. Of note, this indication was supported by the detection of both WNV and DENV genomes in serum samples collected from febrile patients after 2016.ConclusionsThis study revealed the recent re-emergence of WNV and DENV in Gabon as well as the latest seroprevalence state of the major arboviruses, which indicated the different potential risks of virus infections and virus-specific circulation patterns. This information will be helpful for public health organizations and will enable a rapid response towards these arbovirus infections, thereby preventing future spread in the country.

Highlights

Increasing arbovirus infections have been a global burden in recent decades
All samples were screened for IgG antibodies to the six targeted arboviruses (WNV, Dengue virus (DENV), Zika virus (ZIKV), yellow fever virus (YFV), chikungunya virus (CHIKV), and Rift Valley fever virus (RVFV)) using an in-house indirect Enzyme-linked immunosorbent assay (ELISA)
To avoid overestimation of prevalence due to crossreactivity within the genus Flavivirus (WNV, DENV, ZIKV, and YFV), cross-reactivity was examined in advance using each arbovirus seropositive control

Summary

Introduction

Increasing arbovirus infections have been a global burden in recent decades. Many countries have experienced the periodic emergence of arbovirus diseases. With the geographic expansion of vector habitats and an increasing impact on susceptible populations, arboviruses have become emerging or re-emerging pathogens. Zika virus (ZIKV) has attracted global attention since an outbreak in Brazil in 2015, owing to its rapid spread to other countries and possible relationship with severe birth defects caused by infection with the virus during pregnancy [4]. Despite the availability of an effective vaccine, the re-emergence of infections with the yellow fever virus (YFV), has been continually reported in tropical countries, including Brazil, Angola, the Republic of the Congo, and the Domestic Republic of the Congo, [6, 7]

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