Tropical virus causes blackbird death

Thousands of blackbirds succumb to the Usutu virus

14/09/2011

Thousands of blackbirds have mysteriously lost their lives in the past two months. In some regions of southern Germany, songbirds have almost completely disappeared, reports the German Nature Conservation Union (NABU). Scientists at the Bernhard Nocht Institute for Tropical Medicine (BNI) have now discovered a possible cause of the animals' death - a tropical virus originally from Africa.

The researchers around the head of virological diagnostics at BNI, Dr. med. Jonas Schmidt-Chanasit, with the aid of a rapid test developed last year, detected the so-called Usutu virus in a dead blackbird from Birkenau, Hesse. Though „remains to be proved“, if „the mass extinction of the birds is caused by the Usutu virus“, but the assumption was obvious, Dr. Schmidt-Chanasit. The death of blackbirds in recent months, especially in the southern Hesse, Baden-Württemberg and Rhineland-Palatinate, is probably due to the mosquito-borne tropical virus. The Usutu viruses can also affect humans, so that the growing spread of the pathogen in the opinion of the experts is quite concerned about.

Mosquitoes as transmitters of dangerous viruses
The Hamburg scientists of the BNI around Dr. med. Schmidt-Chanasit had already detected the Usutu virus in mosquitoes for the first time last year and already warned against the spread of the germs in Germany. The current „Diagnosis is the first success for a functioning, reliable early warning system, which we wanted to establish with the major project 'occurrence and vector competence of mosquitoes in Germany'“, explained Dr. Jonas Schmidt-Chanasit. According to the BNI expert, it is important to monitor the spread of mosquito-borne viruses in Germany in order to predict the potential hazards to humans and animals. The spread of Usutu viruses, which probably led to the death of thousands of blackbirds, is to be assessed with concern by the BNI. Although are „In Germany so far no infections of humans were diagnosed“, but the risk of Usutu virus spilling over humans increases with the spread of the pathogens, Dr. Schmidt-Chanasit. However, there are no indications so far, „that the Usutu virus in Germany is transmitted to humans or even causes an epidemic“, emphasized the head of virological diagnostics at the BNI.

Usutu fever as a result of infection with the tropical viruses
According to BNI experts, signs of infection with Usutu virus include fever, headaches and rashes. In particularly severe disease, life-threatening brain inflammation (encephalitis) can also occur. For this reason, the state health ministry of Baden-Württemberg was informed immediately as a result of the current evidence. The medical significance of the results of the BNI for the population in Germany is now to be examined in further investigations. Schmidt-Chanasit. According to the experts of the Bernhard Nocht Institute for Tropical Medicine, an infection with Usutu viruses was first diagnosed in patients in Italy in autumn 2009. The sporadic infections that have since been recorded have been particularly severe in immunocompromised and elderly people, according to the BNI.

Spread of tropical viruses in Europe
In recent years, so-called tropical viruses such as the pathogens of West Nile fever or dengue fever have been detected more and more frequently in Europe. Most of the viruses arrive via migratory birds to Europe and as the mosquitoes transmitting mosquitoes such as the Asian tiger mosquito now feel at home in the northern latitudes during the warmer climates, the pathogens can spread relatively quickly. In this way, the native Usutu virus in the blackbird population massively increased and caused the death of thousands of blackbirds in the past two months, the experts suspect. (Fp)

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Picture: Jens Bredehorn