Serological Evidence of West Nile and Usutu Viruses Circulation in Domestic and Wild Birds in Wetlands of Mali and Madagascar in 2008

Abstract

The geographical distribution and impact on animal and human health of both West Nile and Usutu viruses, two flaviviruses of the Japanese encephalitis complex, have been increasing during the past two decades. Both viruses circulate in Europe and Africa within a natural cycle between wild birds and mosquitoes, mainly from the Culex genus. We retrospectively analyzed sera from domestic and wild birds sampled in 2008 in two wetlands, namely the Inner Niger Delta, Mali, and the Lake Alaotra area, Madagascar. Sera were first tested using a commercial ID Screen West Nile Competition Multi-species ELISA kit. Then, positive sera and sera with insufficient volume for testing with ELISA were tested with a Microneutralization Test. In Mali, the observed seroprevalence in domestic birds was 28.5% [24.5; 32.8] 95%CI, 3.1 % [1.8; 5.2] 95%CI, 6.2% [3.4; 10.2] 95%CI and 9.8 % [7.3; 12.8] 95%CI, for West Nile virus (WNV), Usutu virus (USUV), undetermined flavivirus, and WNV/USUV respectively. Regarding domestic birds of Madagascar, the observed seroprevalence was 4.4 % [2.1; 7.9]95%CI for WNV, 0.9% [0.1; 3.1] 95%CI for USUV, 1.3% [0.5; 2.8] 95%CI for undetermined flavivirus, and null for WNV/USUV. Among the 150 wild birds sampled in Madagascar, two fulvous whistling-ducks (Dendrocygna bicolor) were positive for WNV and two for an undetermined flavivirus. One white-faced whistling-duck (Dendrocygna viduata) and one Hottentot teal (Spatula hottentota) were tested positive for USUV. African and European wetlands are linked by wild bird migrations. This first detection of USUV—as well as the confirmed circulation of WNV in domestic birds of two wetlands of Mali and Madagascar—emphasizes the need to improve the surveillance, knowledge of epidemiological patterns, and phylogenetic characteristics of flavivirus in Africa, particularly in areas prone to sustained, intense flavivirus transmission such as wetlands.

Impact of host age on viral and bacterial communities in a waterbird population

“…We hypothesise that the abundance of viruses with zoonotic potential is likely to be similarly affected by host age as the non-zoonotic viruses identified here. This is supported by previous studies; for example, influenza A virus is more prevalent in juvenile than adult birds [82], and seroprevalence against influenza A and flaviviruses such as Usutu virus can be higher in adult birds [33,83]. The spillover risk of a broad range of viruses, including half of the families of bird-infecting viruses identified here as being differentially abundant according to bird age (i.e.…”

One Health surveillance of West Nile and Usutu viruses: a repeated cross-sectional study exploring seroprevalence and endemicity in Southern France, 2016 to 2020

“…A competitive enzyme-linked immunosorbent assay (cELISA, ID Screen West Nile Competition Multi species ELISA kit, IDvet, France) was used for the detection of flavivirus antibodies (IgG and IgM) in sera [ 27 ] from humans, dogs and horses, according to the manufacturer’s instructions.…”

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

“…Several other studies have shown the co-circulation of USUV and WNV viruses in humans and animals, particularly in Europe [ 26 , 27 ]. Horses, dogs, domestic birds and chickens have been identified as accidental hosts of USUV and WNV [ 7 , 20 , 28 , 29 , 30 , 31 ]. Horses are known as a species particularly susceptible to WNV and USUV infection, and are considered as valuable sentinels of the risk of WNV epizootic transmission [ 32 , 33 ].…”

“…A WNV serological survey of domestic pigeons in Nigeria reported a seroprevalence of 3.5% [ 39 ]; which is close to the 4.76% rate found in our study. Another study conducted in Mali showed the presence of USUV and WNV antibodies in other species of domestic bird (duck and chicken) [ 30 ]. A large-scale study on domestic pigeons in Burkina Faso would make it possible to better situate their share in the circulation of USUV and WNV.…”