Questions and answers: Usutu virus

What is it?

The Usutu virus originated in Africa and is named after the Usutu river in Swaziland. It can cause disease in birds and is transmitted by midges. The virus rarely causes disease in humans.

  • Which species of bird are affected?
    Wild birds: Deaths from Usutu virus infection have been reported in a wide range of songbirds in many countries with mass die-outs predominantly seen in blackbirds and sparrows.
  • Captive birds: Deaths have been described in captive owls: Lapland owls are particularly affected.

How does the virus affect wild bird populations?

The first case of Usutu virus was reported in the Netherlands in 2016. Whenever a virus first enters a population the death count is high. It is not known how long it will take for the population to develop sufficient immunity to the virus which will result in fewer deaths. Furthermore, it is not yet clear as to how long the virus will persist in the Netherlands and, therefore, what the overall affect on bird poluations will be.

Where else in Europe is Usutu virus found?

The virus originates from Southern Africa. The first outbreak in birds in Europe was seen in Italy in 1996 and was followed by an outbreak in Austria in 2001. The virus has subsequently been found in birds in Spain, Croatia, Hungary, Switzerland, Chechnya, Germany and Belgium. These countries reported mass die-offs of blackbirds. The virus was first seen in birds in the Netherlands in 2016.

What are the signs of infection in birds?

Birds infected with Usutu virus may show one or more of the following signs:
General illness, apathy, puffed-up feathers, gasping for breath, stopping drinking, general weakness (i.e. not flying, flying low over short distances and resting frequently), drooping head and / or wings and loss of balance. The range of signs depends on which organs (e.g. heart, brain, peripheral nerves) are affected. These signs are not unique to Usutu virus and diagnosis must be based on further testing.

Is my cat / dog at risk if it picked up / ate a dead blackbird?

Usutu virus is an avian virus; in European countries where infected birds have been found, cats and dogs did not become sick, suggesting that the virus does not pose a risk to these animals.

How can captive birds be protected against infection?

The best way to protect birds is to minimize their exposure to infected mosquitos and midges.

  • Ensure that there is no standing water in bird cages where midges can lay their eggs.
  • Use mosquito nets around bird cages or house birds indoors, covering windows with insect screens.
  • There is currently no vaccine for birds against Usutu virus.

Can sick birds be treated?

There is no specific medicine for Usutu virus infection; care of infected birds consists of treating the symptoms.

Does the virus pose a risk to human health?

The virus is transmitted by biting midges, particularly those belonging to the genus Culex. Human infection is rare but not impossible. Despite several large Usutu virus outbreaks in bird populations in Europe, only several people are reported to have become ill due to infection; the majority of these were immunosuppressed. Nonetheless, researchers have suggested that Usutu virus infection be considered in patients with meningitis or central nervous system symptoms1.

What precautionary measures can be taken when handling sick or dead birds?

There are no specific measures for handling birds infected with Usutu virus. However, when handling sick or dead birds you should always follow the general hygiene guidelines outlined on the DWHC FAQ pages.