TY - JOUR
T1 - Serological evidence of continuing high Usutu virus (Flaviviridae) activity and establishment of herd immunity in wild birds in Austria
AU - Meister, Tanja
AU - Lussy, Helga
AU - Bakonyi, Tamás
AU - Šikutová, Silvie
AU - Rudolf, Ivo
AU - Vogl, Wolfgang
AU - Winkler, Hans
AU - Frey, Hans
AU - Hubálek, Zdeněk
AU - Nowotny, Norbert
AU - Weissenböck, Herbert
N1 - Funding Information:
This study was funded by a grant from the Austrian Federal Ministry for Health and Womenś Issues, the grant OTKA D048647, and partially supported by the Grant Agency of the Czech Academy of Sciences (IAA600930611).
PY - 2008/3/18
Y1 - 2008/3/18
N2 - Usutu virus (USUV), family Flaviviridae, has been responsible for avian mortality in Austria from 2001 to 2006. The proportion of USUV-positive individuals among the investigated dead birds decreased dramatically after 2004. To test the hypothesis that establishment of herd immunity might be responsible, serological examinations of susceptible wild birds were performed. Blood samples of 442 wild birds of 55 species were collected in 4 consecutive years (2003-2006). In addition, 86 individuals from a birds of prey rehabilitation centre were bled before, at the peak, and after the 2005 USUV transmission season in order to identify titre dynamics and seroconversions. The haemagglutination inhibition test was used for screening and the plaque reduction neutralization test for confirmation. While in the years 2003 and 2004 the proportion of seropositive wild birds was <10%, the percentage of seroreactors raised to >50% in 2005 and 2006. At the birds of prey centre, almost three quarters of the owls and raptors exhibited antibodies before the 2005 transmission season; this percentage dropped to less than half at the peak of USUV transmission and raised again to almost two thirds after the transmission season. These data show a from year to year continuously increasing proportion of seropositive wild birds. The owl and raptor data indicate significant viral exposure in the previous season(s), but also a number of new infections during the current season, despite the presence of antibodies in some of these birds. Herd immunity is a possible explanation for the significant decrease in USUV-associated bird mortalities in Austria during the recent years.
AB - Usutu virus (USUV), family Flaviviridae, has been responsible for avian mortality in Austria from 2001 to 2006. The proportion of USUV-positive individuals among the investigated dead birds decreased dramatically after 2004. To test the hypothesis that establishment of herd immunity might be responsible, serological examinations of susceptible wild birds were performed. Blood samples of 442 wild birds of 55 species were collected in 4 consecutive years (2003-2006). In addition, 86 individuals from a birds of prey rehabilitation centre were bled before, at the peak, and after the 2005 USUV transmission season in order to identify titre dynamics and seroconversions. The haemagglutination inhibition test was used for screening and the plaque reduction neutralization test for confirmation. While in the years 2003 and 2004 the proportion of seropositive wild birds was <10%, the percentage of seroreactors raised to >50% in 2005 and 2006. At the birds of prey centre, almost three quarters of the owls and raptors exhibited antibodies before the 2005 transmission season; this percentage dropped to less than half at the peak of USUV transmission and raised again to almost two thirds after the transmission season. These data show a from year to year continuously increasing proportion of seropositive wild birds. The owl and raptor data indicate significant viral exposure in the previous season(s), but also a number of new infections during the current season, despite the presence of antibodies in some of these birds. Herd immunity is a possible explanation for the significant decrease in USUV-associated bird mortalities in Austria during the recent years.
KW - Herd immunity
KW - Serology
KW - USUV
KW - Usutu virus
KW - Wild birds
UR - http://www.scopus.com/inward/record.url?scp=38749092249&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=38749092249&partnerID=8YFLogxK
U2 - 10.1016/j.vetmic.2007.08.023
DO - 10.1016/j.vetmic.2007.08.023
M3 - Article
C2 - 17869454
AN - SCOPUS:38749092249
SN - 0378-1135
VL - 127
SP - 237
EP - 248
JO - Veterinary Microbiology
JF - Veterinary Microbiology
IS - 3-4
ER -