Serological Survey of Mosquito-Borne Arboviruses in Wild Birds from Important Migratory Hotspots in Romania

Abstract

In the context of climate change, globalization, and enhanced human traveling, arboviruses continue to represent a threat to public health. West Nile and Usutu viruses are mosquito-borne viruses belonging to the Flaviviridae family (Flavivirus genus) and members of the Japanese encephalitis virus serocomplex. Included in the Togaviridae family (Alphavirus genus), the Sindbis virus is also vectored by mosquitoes. In the present study, we aimed to analyze the presence of antibodies concerning the abovementioned viruses in migratory and resident birds in the South-Eastern region of Romania, as avian hosts represent the main reservoir for human infection. Blood samples were collected from wild birds between May 2018 and October 2019 in nine locations from three counties. All the samples were serologically tested by ELISA and a serum neutralization test. Overall, a seroprevalence of 8.72% was registered for the West Nile virus, 2.71% for the Usutu virus, and 0% for the Sindbis virus. To our best knowledge, this is the first large-scale comprehensive study to assess the West Nile virus seropositivity in wild birds and the first serological confirmation of the Usutu virus in wild birds in Romania. Moreover, this is the only follow-up study reviewing the current seroprevalence of the Sindbis virus in Romania since 1975.

Unexpected Pathogen Diversity Detected in Australian Avifauna Highlights Potential Biosecurity Challenges

“…Although urbanisation, habitat loss and modification are the leading cause of population decline in psittacine species [ 50 ], infectious viral agents, such as BFDV and PsAHV1, are considered a significant threat to the persistence of robust populations of many psittacine species and add to the cumulative risk factors for threatened taxa. Avian species are additionally vectors for various zoonotic RNA viruses, which can cause disease within infected birds and humans, including influenza viruses, West Nile virus and Usutu virus [ 46 , 51 ]. However, the screening of these pathogens was beyond the scope of this study.…”

First Detection and Molecular Characterization of Usutu Virus in Culex pipiens Mosquitoes Collected in Romania

“…To our knowledge, this is the first sequence-based evidence of USUV circulation in our country. However, seroprevalence study showed the circulation of USUV in wild birds sampled in localities in Tulcea county, including Danube Delta Biosphere Reserve, and in Constanta county [ 16 ] ( Figure 1 ), but not in human population in other part of the country [ 17 ]. The sampling sites chosen for our four-year study were Danube Delta and Bucharest metropolitan area.…”

“…Although we could not find evidence of USUV circulation in mosquito vectors collected between 2012 and 2013 in Danube Delta, a latter seroprevalence study (2018–2019) documented the presence of USUV in wild birds sampled in the area, mainly belonging to Passeriformes and Bucerotiformes orders. Of note, the species presenting the highest seroprevalence in this study was the common blackbird [ 16 ]. However, the same study failed to detect USUV specific antibodies in birds sampled in Bucharest in the same period when the C. pipiens s.l.…”

“… Mosquito sampling sites, South-Eastern Romania, 2012–2013 and 2019–2020. Sampling sites where wild birds tested positive for USUV antibodies were reported by Coroian et al [ 16 ]. …”

“…Seroprevalence study on wild birds conducted in South-Eastern Romania between 2018 and 2019 presented indirect evidence of USUV circulation in this country [ 16 ]. However, serological survey conducted between 2019 and 2020 on healthy blood donors showed no evidence of USUV circulation in human population from the North-Western region of Romania [ 17 ].…”