Situation in Austria
The Usutu virus was first detected in Europe in 2001 in the context of a bird mortality in Austria. It mainly affected blackbirds and tawny owls. The first Usutu virus infections in humans in Europe were also reported in Austria in 2003, among others in a young man with a rash from the Vienna area. Since 2016, Usutu virus infections in birds have increased again in Austria. According to a paper published in the journal EUROSURVEILLANCE on Oct. 12, 2017, Usutu virus was also detected for the first time in Austria in 2017 in six blood donors from the Vienna/Lower Austria/Burgenland area. None of the Austrian blood donors showed clinical symptoms before or after blood donation. These Austrian cases and observations in Europe suggest that Usutu virus is increasingly spreading. Infections of humans by Usutu virus are currently not notifiable.
Usutu virus (USUV) is a flavivirus and belongs to the antigenic complex of the Japanese encephalitis virus. Usutu virus first appeared in South Africa in 1959 and was named after a river in Swaziland. The virus is transmitted by mosquitoes. Wild birds are considered the main hosts, which can also carry and spread the virus. Human infections do not pose a risk of spreading the virus.
The Usutu virus was first detected in Europe in 2001 in the context of a bird death in Austria. It mainly affected blackbirds and tawny owls. Infection in humans was originally reported only in two cases in Africa in 1981 and 2004. The first Usutu virus infections in humans in Europe were reported in Austria, as early as 2003, including in a young man with a rash from the Vienna area. In 2009, USUV was detected in two critically ill, immunocompromised individuals in Italy. Since 2016, Usutu virus infections in birds have again occurred more frequently in Austria.
Transmission occurs through mosquito bites. Other transmission routes have not yet been confirmed. Transmission through blood or organ donations has also not yet been documented.
An infection of humans by the Usutu virus usually runs without symptoms, therefore it usually remains undetected. Mild symptoms such as fever and skin rash are occasionally observed. However, the Usutu virus can lead to serious neurological diseases in people who are immunosuppressed, as no signs of illness occur (asymptomatic course).
There is currently no specific therapy for infections with Usutu virus. Symptomatic therapy is directed against any symptoms that may occur. As a preventive measure, mosquito bites should be avoided as far as possible in regions where USUV is endemic - in Austria these are the provinces of Vienna, Lower Austria, Burgenland and parts of Styria.
The laboratory diagnosis is made by the detection of pathogen nucleic acid in blood or serum samples of the patient. No commercial antibody tests are available for the serological detection of Usutu virus in human blood. Instead, antibody detection tests for West Nile Virus are used. Subsequently, a so-called neutralisation test is carried out in order to clarify the exact cause of infection.