Usutu virus, Austria and Hungary, 2010–2016

Abstract

Usutu virus (USUV, Flaviviridae) was first reported in Europe in Austria in 2001, where it caused wild bird (mainly blackbird) mortality until 2005. Since 2006 no further USUV cases were diagnosed in the country. However, the virus emerged in other European countries (Hungary, Italy, Switzerland, Spain, Germany and the Czech Republic) between 2005 and 2011. In 2016, widespread USUV-associated wild bird mortality was observed in Germany, France, Belgium and the Netherlands. In this study, we report the results of passive monitoring for USUV in Austria and Hungary between 2010 and 2016. In Hungary, USUV caused sporadic cases of wild bird mortality between 2010 and 2015 (altogether 18 diagnosed cases), whereas in summer and autumn 2016 the number of cases considerably increased to 12 (ten blackbirds, one Eurasian jay and one starling). In Austria, USUV was identified in two blackbirds in 2016. Phylogenetic analyses of coding-complete genomes and partial regions of the NS5 protein gene revealed that USUVs from Hungary between 2010 and 2015 are closely related to the virus that emerged in Austria in 2001 and in Hungary in 2005, while one Hungarian sequence from 2015 and all sequences from Hungary and Austria from 2016 clustered together with USUV sequences reported from Italy between 2009 and 2010. The results of the study indicate continuous USUV circulation in the region and exchange of USUV strains between Italy, Austria and Hungary.

Different dynamics of Usutu virus infections in Austria and Hungary, 2017–2018

“…In Austria, no regular USUV monitoring programmes were conducted since 2006 (Bakonyi, Erdelyi, et al, ). However, in 2017 and particularly in 2018, a high number of bird carcasses was submitted by veterinarians, avian research institutions, animal shelters, but predominantly concerned citizens.…”

“…In Hungary, a surveillance programme for passive monitoring of avian influenza cases in wild birds has been in place since 2006. Within the scope of this programme, dead bird samples were also tested for flaviviruses, such as WNV and USUV (Bakonyi, Erdelyi, et al, ). Altogether, birds of 67 different species were tested for USUV infection, 100 in 2017 and 153 in 2018.…”

“…Furthermore, in the UK (Buckley et al, ) and Poland (Hubalek et al, ) serological indications for the presence of USUV were found. In Hungary, only local outbreaks and sporadic USUV cases were detected from 2005 through 2015; while in 2016, samples of 12 birds tested positive (Bakonyi, Erdelyi, et al, ; Bakonyi et al, ). Similar to the situation in Hungary, no further cases were identified in Austria since 2006, until two blackbirds tested positive in autumn 2016 (Bakonyi, Erdelyi, et al, ).…”

“…During the first years of USUV occurrence in Austria (Bakonyi et al, ; Chvala et al, ), as well as in Hungary (Bakonyi et al, ), the only lineage found was Europe 1. This changed in 2015/2016 with the first detections of USUV lineage Europe 2, which has since then become the prevalent lineage found across both countries (Bakonyi, Erdelyi, et al, ). In 2016, USUV lineage Europe 2 was detected for the first time in a human blood donation in Austria, and in six donations in 2017 (Bakonyi, Jungbauer, et al, ).…”

Prevalence and molecular epidemiology of West Nile and Usutu virus infections in Croatia in the ‘One health’ context, 2018

“…In Europe, USUV emerged in 1996, causing considerable die‐off of Eurasian blackbirds (Weissenbock, Bakonyi, Rossi, Mani, & Nowotny, ). In the following years, USUV‐associated bird mortality, mainly among blackbirds and great grey owls was documented in many European countries (Bakonyi et al, ). In the summer of 2016, Belgium, France, Germany and the Netherlands reported widespread USUV activity in wild and captive birds (Cadar et al, ; Rijks et al, ).…”