The Usutu virus was first identified in Europe in Austria in 2001, where it caused significant mortality among birds (https://wwwnc.cdc.gov/eid/article/8/7/02-0094_article), affecting mainly blackbirds and great grey owls. Originally, there were only two cases involving human infections reported in Africa in 1981 and 2004. The first USUV infections in humans in Europe were documented in Austria in 2003, including a young man from the metropolitan area of Vienna suffering from a rash. The virus was also detected in two severely ill patients with immuno-suppression in Italy in 2009. The number of USUV infections in birds has risen again in Austria since 2016 (see: http://www.nature.com/emi/journal/v6/n10/full/emi201772a.html).
The Usutu virus was found in six blood donors from the Vienna/Lower Austria/Burgenland region for the first time in 2017, according to a paper published in the science journal EUROSURVEILLANCE on 12th October 2017. None of the Austrian donors showed any clinical symptoms before or after donating blood. These Austrian cases and observations in Europe lead to the conclusion that the Usutu virus is spreading. USUV infections in humans are not notifiable at present.
The virus is transmitted via mosquito bites. Other routes of transmission have not been confirmed to date. Transmission via donated blood or organs has not been documented to date.
An USUV infection in humans usually progresses without symptoms. Mild symptoms, such as fever and skin rashes, may occur in individual cases. However, USUV could lead to severe neurologic conditions in humans with suppressed immune systems.
Most USUV infections remain undetected given the absence of symptoms in most cases (asymptotic progression).
There is no specific therapy for infections with the Usutu virus at present. Symptomatic therapy targets potential symptoms.
A prophylactic measure in regions where USUV is endemic – this would comprise Vienna, Lower Austria, Burgenland and parts of Styria in Austria – is to avoid mosquito bites as much as possible.
Medical laboratory diagnosis is carried out by detecting the virus’s nucleic acid in a patient’s blood or serum samples. There are no commercial antibody detection tests available for the serologic detection of USUV in human blood. Instead, West Nile virus antibody detection tests are used. This is then followed by a so-called neutralization test to find out the exact cause of the infection.
Questions regarding human diagnostics:
National Reference Center for Flavivirus Infections in Humans
Center for Virology, Medical University Vienna
Kinderspitalgasse 15, 1095 Vienna
Tel.: 01 40160 65517
Questions regarding veterinarian diagnostics:
AGES-Austrian Agency for Health and Food Safety GmbH
Institute for Veterinary Disease Control Mödling
Robert Koch-Gasse 17, 2340 Mödling
Tel.: 050555 38112
Test for Usutu virus infections in birds are also carried out at the University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna. Further information: Univ.-Prof. Dr. Norbert Nowotny: Norbert.Nowotnyno@Spam@vetmeduni.acno.Spam.at