Screening of Circulation of Usutu and West Nile Viruses: A One Health Approach in Humans, Domestic Animals and Mosquitoes in Burkina Faso, West Africa

Abstract

Usutu virus (USUV) and West Nile virus (WNV) are phylogenetically closely related arboviruses. These viruses mainly follow an enzootic cycle involving mosquitoes and birds, but they occasionally infect humans and other mammals, inducing neurotropic disorders. Since the discovery of USUV, only two human cases have been reported in Africa, including one in Burkina Faso in 2004. Since then, no studies have been conducted to measure the extent of the circulation of this virus in Burkina Faso, and no study regarding the circulation of WNV has been conducted. Our study aimed to determine the seroprevalence of USUV and WNV in blood donations and in animals (horses, dogs, chickens and pigeons) and to perform molecular screening in patients with febrile fever and in Culex quinquefasciatus and Aedes aegypti mosquitoes. The prevalence of USUV and WNV was studied by serological (ELISA and microneutralization tests) and molecular analyses (RT-qPCR) of mosquito, dog, domestic bird, horse, and human samples in Burkina Faso between 2019 and 2021. We detected a very active transmission of both viruses in Burkina Faso. WNV and USUV seroprevalence is particularly high in humans (19.16% and 14.17%, respectively) and horses (17.28% and 6.17%). Molecular screening did not detect WNV or USUV in the mosquito or human samples tested. Our study shows an active spread of USUV and WNV in Burkina Faso, especially for WNV. This study highlights the value of developing surveillance programs to better prevent, detect, and alert people to USUV and WNV circulation in both primary and incidental hosts.

A metagenomics-based survey of the virus diversity in mosquito vectors allows the first detection of Sindbis virus in Burkina Faso

“…SINV detection was validated through virus isolation and PCR from non-blood-engorged females. Previously, a PCR-based survey on the same samples did not detect six mosquito-borne viruses potentially present in the country (dengue virus, Zika virus, chikungunya virus, West Nile virus and Usutu virus) [20,21], just like found here in the metagenomics survey. Comparison of the surveys using either PCR or metagenomics suggests that viral metagenomics on mosquitoes is a suitable tool for virus surveillance in regions with a high viral diversity, as shown by others [46,47].…”

“…This West-African country is highly connected to other regions in Africa and other continents through human and wildlife movement [19]. Several mosquito-borne viruses have been previously detected in Burkina Faso [20][21][22]. Nevertheless, studies have focused on a limited number of these viruses.…”

“…To further facilitate a comprehensive exploration of viral diversity, environments with different levels of human activity, and thus likely to harbour different viruses, were sampled for three consecutive years. Previously, we had screened this mosquito collection for several mosquito-borne viruses -including dengue virus, Zika virus, West Nile virus and chikungunya virus -using RT-PCR [20,21]. In this study, we have used shotgun metagenomics to screen the mosquito collection.…”

Human Usutu Virus Infections in Europe: A New Risk on Horizon?

“…Fever and skin rash were reported for both cases. Since, all human cases of USUV infection have been reported in Europe only, although seroprevalence studies conducted in other countries highlight the active circulation of this virus in the African continent [ 50 , 51 ] ( Table 1 ).…”

Vector competence of Swedish Culex pipiens mosquitoes for Usutu virus

“…Subsequent human cases have emerged primarily in Europe. Despite evidence of active virus circulation in Africa from seroprevalence studies no further human disease cases have been reported there [ 10 , 11 ].…”