Acute spread of the Usutu virus in Germany

Usutu virus kills numerous blackbirds - First humans infected in Germany

20/08/2012

The Usutu virus has already killed many blackbirds in the past year. Also this summer, the tropical pathogens continue to spread in Germany. The researchers' hope for the development of resistance has apparently not been confirmed. Meanwhile, a first infection was detected in humans.

The Bernhard Nocht Institute for Tropical Medicine in Hamburg warns of another Blackbird death by the Usutut virus during the summer months. In Southwest Germany masses of blackbirds died of the tropical pathogens. „Unfortunately, fears have now been confirmed that the Usutu virus has been active again in the known outbreak region since June and that many birds die of the infection“, explained Dr. Norbert Becker, scientific director of the „Municipal working group to combat the mosquito plague“ (KABS) and lecturer at the University of Heidelberg. For example, up to ten dead blackbirds are found daily in the area around Ludwigshafen in Rhineland-Palatinate.

Transmission of the Usutu virus by mosquitoes
The Usutu virus, originally from Africa, is transmitted by mosquitoes and occurs in this country as a result, especially during the summer months. In general, the pathogens can infect humans, mammals and birds. In the latter case, an infection often ends in death. According to Dr. Jonas Schmidt-Chanasit, Head of Virological Diagnostics at the Bernhard Nocht Institute, offers the „Current outbreak offers a unique opportunity to study the complex biotic interactions between viruses, mosquitoes and birds in Germany, taking environmental conditions into account.“ The researchers were quite surprised that "the pathogens in the blackbird population claim as many victims this year as in the previous year". Actually, the experts of the BNI and the KABS had hoped that "the birds will develop resistance to the Usutu virus and thus stop the advance of the pathogens".

Weather conditions favor the spread of the tropical virus
Instead, there are many indications that the Usutu virus will continue to spread in Germany, said the scientific director of KABS. In North Rhine-Westphalia, the pathogens have now been detected in a dead blackbird and two finds were reported from the region around Freiburg in Baden-Württemberg. The spread of the Usutu virus will this year by the favorable weather conditions for mosquitoes further promoted. "The rain and the storms promote the multiplication of mosquitoes, which in turn accelerates the spread of Usutu viruses," said the experts.

Millions of dead birds by Usutu viruses?
The spread of Usutu viruses can not be stopped or only with very costly measures Schmidt-Chanasit. In his view, years or decades can pass before the spread of the Usutu virus goes back. During this time, dramatic decreases in the blackbird population are to be expected. The viruses, according to Dr. Schmidt-Chanasit. the potential in the coming years to collect millions of birds throughout Germany. Even chicks in their nest are currently more likely to die from the pathogens. However, how the spread of the Usutu virus will actually develop remains unclear.

Infection risk for humans
In addition to the deadly consequences for blackbirds, the Usutu virus also carries a certain risk of infection for humans. For example, the BNI experts used a blood sample to detect the antibodies against the pathogens when analyzing the blood of 4,200 blood donors from the Rhine-Neckar region. According to this, the patient from the Hessian Groß-Gerau had been ill some months earlier with an infection with the Usutu virus (Usutu fever). Jonas Schmidt-Chanasit ... However, the typical symptoms of Usutu fever such as headache, fever and itchy skin rash are easily confused with other illnesses and are therefore, according to the experts often not recognized as an infection with the tropical virus, but, for example, diagnosed as summer flu. The actual number of Usutu virus infections could therefore be much higher than previously thought. In severe cases, those affected may suffer from encephalitis, which can have life-threatening consequences for the patient. Nevertheless, a reason for panic was not given, as Schmidt-Chanasit emphasized. "Yes, it has come to an infection, but it is not dramatic now, after all, it is only one of 4200 - just do not panic," said Schmidt-Chanasit. (Fp)

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Another blackbird death by Usutu viruses
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Image: Gerd Altmann (representation is a tracing)