Evidence for an independent third Usutu virus introduction into Germany

In the summer of 2016, Belgium, France, Germany and the Netherlands reported widespread Usutu virus (USUV) activity based on live and dead bird surveillance. The causative USUV strains represented four lineages, of which two putative novel lineages were most likely recently introduced into Germany and spread to other western European countries. The spatial extent of the outbreak area corresponded with R0 values > 1. The occurrence of the outbreak, the largest USUV epizootic registered so far in Europe, allowed us to gain insight in how a recently introduced arbovirus with potential public health implications can spread and become a resident pathogen in a naïve environment. Understanding the ecological and epidemiological factors that drive the emergence or re-emergence of USUV is critical to develop and implement timely surveillance strategies for adequate preventive and control measures. Public health authorities, blood transfusion services and clinicians in countries where USUV was detected should be aware of the risk of possible USUV infection in humans, including in patients with unexplained encephalitis or other neurological impairments, especially during late summer when mosquito densities peak.

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“…The Africa 2 strain that killed two great grey owls in the Berlin Zoo in 2015 [28] was found in 2016 outside the zoo, in a blackbird.…”

Section: Resultsmentioning

confidence: 99%

Widespread activity of multiple lineages of Usutu virus, western Europe, 2016

et al. 2017

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“…USUV activity after the first outbreak in Germany in 2011–2012 was remarkably lower in the following years, as reflected in the detection of fewer USUV-positive dead birds ( 25 , 26 ). However, the common blackbird population in the USUV-suitable areas continued to decline after the initial outbreak.…”

Section: Discussionmentioning

confidence: 99%

“…The USUV data in Germany were collected as part of a dead bird surveillance program ( 12 , 14 , 25 , 26 ). After the description of a USUV outbreak in wild birds in Germany in 2011, we requested, by press releases and media dissemination, that citizens send dead birds for USUV screening at national reference laboratories.…”

Section: Methodsmentioning

confidence: 99%

Distribution of Usutu Virus in Germany and Its Effect on Breeding Bird Populations

Lühken¹,

Jöst²,

Cadar³

et al. 2017

Emerg. Infect. Dis.

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Usutu virus (USUV) is an emerging mosquitoborne flavivirus with an increasing number of reports from several countries in Europe, where USUV infection has caused high avian mortality rates. However, 20 years after the first observed outbreak of USUV in Europe, there is still no reliable assessment of the large-scale impact of USUV outbreaks on bird populations. In this study, we identified the areas suitable for USUV circulation in Germany and analyzed the effects of USUV on breeding bird populations. We calculated the USUV-associated additional decline of common blackbird (Turdus merula) populations as 15.7% inside USUV-suitable areas but found no significant effect for the other 14 common bird species investigated. Our results show that the emergence of USUV is a further threat for birds in Europe and that the large-scale impact on population levels, at least for common blackbirds, must be considered.

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“…These sequences were closely related to the mosquito strain reported in Catalonia (Spain) in 2006 8 and, thus, point to different and frequent introduction of the virus in Europe and to a probable higher bird mortality than initially assumed. 9 Further phylogenetic studies have reported an important differentiation between Central European and African USUV sequences, resulting in phylogeographic clustering of eight distinct lineages. 10 Phylogenetic trees from USUV European sequences indicated a common ancestor for the majority of them, except for some sequences from Spain 8 and Germany, 9 grouped in a branch divided into four well-supported clades.…”

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confidence: 99%

“…9 Further phylogenetic studies have reported an important differentiation between Central European and African USUV sequences, resulting in phylogeographic clustering of eight distinct lineages. 10 Phylogenetic trees from USUV European sequences indicated a common ancestor for the majority of them, except for some sequences from Spain 8 and Germany, 9 grouped in a branch divided into four well-supported clades. 11 Notably, sequences collected in Spain from birds differed in their phylogenetic origin than those from mosquitoes.…”

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confidence: 99%

Usutu virus: current knowledge and future perspectives

Saiz¹,

Blázquez²

2017

VAAT

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Abstract:The Flavivirus genus (Flaviviridae family) contains important pathogens such as yellow fever virus, Japanese encephalitis virus, St Louis encephalitis virus, West Nile virus, Usutu virus (USUV), Zika virus, and dengue virus, many of which constitute a worrisome threat to global human and animal health. USUV is transmitted by mosquitoes and, as any other flavivirus, is an enveloped plus-strand RNA virus. The virus was first isolated from Culex neavei mosquitoes in South Africa in 1959 near the Usutu River, from where it takes its name. Since then, the virus was confined to Africa until its first detection in Austria in 2001, although it was probably present in Europe since 1996 or even earlier. After that, USUV has spread throughout Europe, causing a considerable mortality among birds and a few neurologic cases in humans. The main USUV natural hosts are birds, but infection has also been reported in other vertebrate species, including humans. The fast spread of the virus through the continent, the relatively high mortality caused in birds, and the recent neuroinvasive human cases related to USUV infection reported in Europe have raised serious concerns about its possible consequences for public health. Here, an updated review of current knowledge about this emerging pathogen is presented. Keywords: Usutu virus, flavivirus, host cell-virus interactions, surveillance, prophylaxis Biology of the virus Molecular classification and phylogenyUsutu virus (USUV) is a member of the Flavivirus genus within the Flaviviridae family ( Figure 1A). In 2004, the complete genomic sequences of two USUV strains, one African (South Africa-1959) and one European (Vienna-2001), were used to build a phylogenetic tree. These two strains showed a 97% and 99% homology at the nucleotide (nt) and amino acid (aa) level, respectively.1 Both strains were closely related to Murray valley encephalitis virus (73% and 82% nt and aa similarity), Japanese encephalitis virus (71% and 81% nt and aa similarity), and to West Nile virus (WNV; 68% and 75% nt and aa similarity). Nowadays, dozens of complete sequences are available in the data banks. In a recent study, the sequence identity among seven USUV strains was 96%-99% and 99% at the nt and aa levels, respectively.2 The only exception was a 1969 isolate from Central African Republic (CAR-1969) that presented homologies of 81% and 94% at the nt and aa levels with other African sequences ( Figure 1B). Due to these differences, it has been suggested that CAR-1969 formed an USUV subtype strain.3 A comparison with the original South African SAAR-1776 strain showed that the mutations found among different European and African strains were scattered throughout the genome, with some unique substitutions and some that were present

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Evidence for an independent third Usutu virus introduction into Germany

Cited by 49 publications

References 29 publications

Widespread activity of multiple lineages of Usutu virus, western Europe, 2016

Widespread activity of multiple lineages of Usutu virus, western Europe, 2016

Distribution of Usutu Virus in Germany and Its Effect on Breeding Bird Populations

Usutu virus: current knowledge and future perspectives

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