300,000 blackbirds died of Usutu virus

NABU: Tropical Usutu virus kills 300,000 blackbirds

10/09/2012

The German Nature Conservation Union (NABU) has calculated for the first time how many blackbirds actually fell victim to the tropical Usutu virus last year. According to this, around 300,000 birds died as a result of the infection. Despite the numerous deaths, the population of blackbirds is not endangered, according to the NABU.

To capture the impact of the Usutu virus on blackbird populations, NABU researchers have collected bird count data collected since 2006 „Hour of garden birds“ and „Hour of winter birds“ evaluated. They come to the conclusion that in 2011 alone around 300,000 blackbirds have died of the tropical virus. „The figures show that the risk for blackbirds in some regions is high but does not threaten the existence of the country“, explained the NABU Federal Managing Director Leif Miller. However, as the pathogen spreads to the avian population, it also increases the likelihood of human infections. According to the experts of the Bernhard Nocht Institute for Tropical Medicine (BNI), the Community Action Group for the Control of Snaring Plague (KABS) and the University of Heidelberg, the pathogens are transmitted by the Northern Midge. The germ „overwintered in the mosquito females and is only transmitted directly from them. It can not be transmitted from bird to bird or bird to man“, according to the latest release of NABU.

Growing spread of the Usutu virus
The first outbreak of the Usutu virus in Germany was recorded by the experts „in the summer of 2011 on the northern Upper Rhine in the border region of Hesse, Rhineland-Palatinate and Baden-Württemberg“, reports the NABU. In some regions, a veritable mass extinction had been observed. According to the experts, the population of blackbirds declined by around one-third in 21 affected counties within a year. In the summer of 2012, the outbreak area had increased further. „The eruption area has spread slightly in the summer of 2012 and now includes the Rhine plain from Freiburg im Breisgau to Cologne and the Main valley up to Frankfurt am Main and Hanau“, so the message of the nature conservation federation. One reason for panic, however, is not the spread of the pathogens. Because „we can assume that the blackbirds are becoming increasingly resistant to the pathogen“ and so in the affected „Regions like mass extinctions will be less extreme from year to year“, explain the bird expert of the NABU, Lars Lachmann.

Birds suffering from Usutu virus report
Information on the future consequences of the tropical Usutu virus on the blackbird population are so far but pure speculation. In order to monitor and evaluate the development of the virus, the population is still encouraged to report blackbirds that may be suffering from or have died of Usutu virus. The birds can also be sent to the Bernhard Nocht Institute for Tropical Medicine in Hamburg for investigation, reports the NABU in its latest release. Signs of infection are apathetic and uncoordinated behavior as well as bald spots in the area of ​​the head and neck plumage. In principle, most birds could become infected with the pathogen that originated in South Africa and first appeared in Germany in 2011. In fact, however, the virus is mostly blackbird due to the unexplained cause. According to NABU, blackbirds are the most prevalent bird species in Germany, accounting for 13% of the bird population. According to the estimates of the experts live in this country about eight to 16 million breeding pairs, respectively „after the breeding season in the summer about 50 to 60 million individuals.“

Possible transmission of the Usutu virus to humans
By the sting of the Northern house mosquito Usutu viruses can theoretically be transferred to humans, as was already the case with at least one patient from the Hessian large Gerau, in whose blood antibodies against the exciters were proven. The infection is usually much more harmless in humans with symptoms such as fever, headache and itchy skin rash than in birds, but in the worst case can also bring about a life-threatening inflammation of the brain. In particular, older and already weakened patients are endangered in the opinion of experts in an infection with the tropical virus. (Fp)

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Picture: Jens Bredehorn