With the recent heatwave, more and more birds in Germany are contracting the Usutu virus. The pathogen, which is transmitted by mosquitoes, has repeatedly led to the death of birds in recent years. In the summer months in particular, infections have been more frequent because the mosquitoes that transmit the virus multiply more rapidly.

So far, the Bernhard Nocht-Institute for Tropical Medicine has been able to detect the virus in 43 bird carcasses from ten German states. The doctors had investigated 132 suspected cases. The number of unreported cases is likely to be significantly higher.

More than last year

Around 1,500 suspected cases have been reported to the German Nature Conservation Union (NABU) so far, many of them in August.

"The cases reported in 2018 so far clearly exceed the figures from previous years, which indicates a leap in the spread of the virus," explained NABU expert Lars Lachmann.

NABU had registered 1,380 suspected cases in Germany for the entire year of 2017. Last year, the Bernhard Nocht-Institute examined 130 dead birds that citizens had sent in and was able to detect the virus in 45 cases.

First appearance in Europe in 2001

The Usutu virus originates from the Usutu River region in Swaziland, between South Africa and Mozambique. It was first discovered there in 1959. In Europe, it first appeared in Austria in 2001. In the following years there were infections in Hungary, Switzerland and Italy as well.

In Germany, veterinarians detected the first major wave of the disease in 2011. After a few years with fewer reported cases, there was another epidemic in 2016, which mainly affected blackbirds. About 600 dead birds were found at that time.

Due to the humid and warm weather in late summer, the mosquitoes that transmit the Usutu virus have multiplied particularly strongly. This is probably why there was a further increase in infections in 2017 and 2018, bird conservationists say.

Most suspected cases in 2017 were reported in North Rhine-Westphalia, with 500 dead birds. Another 100 entries each came from Baden-Württemberg and Saxony. Since then, the virus has been spreading northwards.

Humans can also become infected with the Usutu virus. The course of the disease is usually mild. In people with immunodeficiency, however, it can lead to fever, headaches, skin rash and, in rare cases, to encephalitis.

fs/cb (dpa)