Low Usutu Virus Seroprevalence in Four Zoological Gardens in Central Europe06 August 2013
Of the birds tested in zoos in Austria, Switzerland and Hungary, one of the chickens and three of the ducks and geese showed antibody titres to Usutu virus but none of the turkeys.
Usutu virus (USUV), a mosquito-borne flavivirus of the Japanese encephalitis virus antigenic group, caused bird die-offs in Austria, Hungary and Switzerland between 2001 and 2009, according to Nicola Buchebner from the University of Veterinary Medicine Vienna in Austria and co-authors there and in Switzerland and Hungary.
In BMC Veterinary Research, they explain that while the zoological gardens of Vienna and Zurich recorded USUV-associated mortality in different species of birds during this period, incidences in Budapest were limited to areas outside the zoo, and in the greater Basel area avian mortality due to USUV infection was not observed at all.
The objectives of their investigation were to gain insight into USUV infection dynamics in captive birds in zoos with varying degrees of virus exposure and to study differences in susceptibility to USUV of different species of birds.
A total of 372 bird sera were collected between October 2006 and August 2007 including from members of the chicken, duck and goose families.
The samples were tested in parallel by haemagglutination inhibition (HI) and 90 per cent plaque reduction neutralization tests (PRNT-90). 8.75 per cent, 5.3 per cent and 6.59 per cent of birds in the zoos of Vienna, Zurich and Basel, respectively, showed USUV-specific antibodies by PRNT-90. No antibodies to USUV were detected in birds of the Budapest zoo. The order Strigiformes (owls) exhibited the highest USUV-seroprevalence, compared to other orders of birds.
Of the sample tested, one of the chickens and three of the ducks and geese showed antibody titres to USUV but none of the turkeys.
The researchers concluded that USUV seems not to pose an imminent threat to zoo bird populations in central Europe at the moment. Depending on a variety of especially environmental factors, however, this may change at any time in the (near) future, as experienced with West Nile virus (WNV). As a result, they suggest continuing with combined WNV and USUV surveillance activities in affected areas.
Buchebner N., W. Zenker, C. Wenker, H.W. Steinmetz, E. Sós, H. Lussy and N. Nowotny. 2013. Low Usutu virus seroprevalence in four zoological gardens in Central Europe. BMC Veterinary Research 9:153. doi:10.1186/1746-6148-9-153
You can view the full report (as a provisional PDF) by clicking here.