Usutu virus linked to blackbird deaths across Switzerland

Several blackbirds have died or become severely ill in Switzerland after contracting the Usutu virus, SRF reports. Cases have recently accumulated in Chur, where authorities received reports of dead or apathetic birds.

Most of the affected birds were blackbirds and had lost many feathers. Tests by the Institute for Fish and Wildlife Health at the University of Bern confirmed the suspected infections.

Infected blackbirds appear very ill, no longer flee from people and usually die within a few days. Symptoms can include neurological problems, staggering and twisting of the head. The disease is also known as blackbird mortality.

The virus is transmitted by mosquitoes and mainly infects songbirds, especially blackbirds. Other birds, including owls, can also become ill. Humans can contract the virus, but severe disease is rare, according to experts at the University of Bern. Transmission from birds to humans is not possible.

In the past two weeks, five birds from five different Swiss cantons were tested at the Bern institute, and all tested positive. Simone Pesano, the institute’s co-head, said this amounted to an accumulation of cases. Sergio Wellenzohn of the Graubünden Office for Hunting and Fisheries said there had been reports and confirmed cases in many Swiss cities.

The last Swiss epidemic occurred about two years ago, Pesano said. The virus was first detected in Central Europe in the early 2000s, while a larger outbreak was recorded in Zurich in 2006. Since then, local and regional outbreaks have occurred repeatedly. The virus appears only during the warmer half of the year, with temperature and humidity influencing mosquito numbers.

There is little that can be done to stop the disease among birds. Dead birds should be disposed of, preferably at a carcass collection centre, and handled with gloves. If a bird is still alive but remains apathetic, Wellenzohn recommends waiting. If it is still there after 24 hours, people can contact the nearest wild bird station or wildlife authorities.

People can reduce mosquito breeding by emptying standing water from plant saucers. Wellenzohn said such water provides a good breeding ground for the mosquitoes that transmit the disease.