Disease: Usutu virus

This page provides general information about this condition; reveal the text by clicking on the green headers. Press releases, results from DWHC investigations as well as other useful documents and relevant literature can be found at the bottom of the page.

Pathogen

Usutu virus, a member of the flaviviridae virus family, is considered to be an emerging disease possibly posing a threat to naive wild and captive bird populations. This mosquito-borne virus is thought to have evolved in Africa and has spread to Europe in the last decades.

Usutu virus is closely related to West Nile Virus that was responsible for the death of thousands of birds, horses and other wildlife species in the USA in 1999. Both diseases can also infect humans.

 

Emergence of Usutu virus, an African mosquito-borne flavivirus of the Japanese encephalitis virus group, central Europe. Emerg. Infect. Dis., 8 (7) (2002)

T.J. Gray, C.E. Webb. A review of the epidemiological and clinical aspects of West Nile virus. Int. J. Gen. Med., 7 (2014)

Susceptible species

Birds are the primary host of this virus, acting as reservoir species, amplifying the virus and spreading infection. Certain species of mosquitoes act as vectors, transmitting disease after ingesting the blood of an infected animal. Many species, including horses, bats and humans can be incidental hosts when they are bitten by a virus-carrying mosquito.

D. Cadar, N. Becker, M. Campos Rde, J. Borstler, H. Jost, J. Schmidt-Chanasit. Usutu virus in bats, Germany, 2013 Emerg. Infect. Dis., 20 (10) (2014)
First serological evidence of West Nile virus activity in horses in Serbia. Vector Borne Zoonotic Dis., 11 (9) (2011)

Signs in animals

Usutu virus caused large numbers of deaths in certain species of European wild birds; when a new virus infects a naive population, mass die-offs resulting in serious population reductions are often the first sign of a disease, particularly in wildlife species. The few reported observations of clinical signs in infected blackbirds included apathy, lack of flight-response, ruffled feathers and weak, uncoordinated movements (ataxia) and seizures. Typical post-mortem findings include enlarged liver and spleen, however, these changes are not unique to Usutu virus infection and molecular testing is necessary for virus identification.

 

Food Safety Risks from Wildlife: Challenges in Agriculture, Conservation, and Public Health. Eds Michele Jay-Russell, Michael P. Doyle. Springer, 2015.

Infection of animals

Infection occurs when birds and other animals are bitten by a virus-carrying mosquito.

Symptoms in people

There are only few case reports of Usutu virus infection in humans; one man with rash and fever in the Central African republic and several immune-compromised patients in Europe who developed neurological disease.

 

Cavrini F, Gaibani P, Longo G, Pierro AM, Rossini G, et al. (2009) Usutu virus infection in a patient who underwent orthotropic liver transplantation, Italy, August–September 2009 . Euro Surveill 14: pii: 19448.

Pecorari M, Longo G, Gennari W, Grottola A, Sabbatini AM, et al. (2009) First human case of Usutu virus neuroinvasive infection, Italy, August–September 2009 . Euro Surveill 14: pii: 19446.

Santini, M., Vilibic-Cavlek, T., Barsic, B. et al. J. Neurovirol. (2015) 21: 92.

Infection of people

The most likely route of infection of humans is through the bite of a virus-carrying mosquito.

Geographical distribution

First identified in South Africa in 1959 where it was not associated with disease in humans or other animals, Usutu virus was first seen in Europe in 2001 when it was identified as the cause of high mortality in blackbirds and great grey owls in Austria. Subsequently, evidence of virus exposure (antibody testing) has been seen in wild and captive birds from a range of European countries including Hungary, the Czech Republic, Switzerland, Spain, Italy, the UK and Southern Germany. The virus is likely to have been spread by migratory species and insect vectors. Evidence of infection has not always associated with disease or population reductions and it has been suggested that some degree of flock-immunity has been acquired by European birds or that avirulent strains of the virus may be circulating and affording cross-protection. The increase in geographical range of Usutu and other related viruses seen in recent years has been associated with the increasing range of insect vectors, linked to climate change.

Weissenböck H, Kolodziejek J, Url A, Lussy H, Rebel-Bauder B and Nowotny N. (2002) Emergence of Usutu virus, an African Mosquito-BorneFlavivirus of the Japanese Encephalitis Virus Group, Central Europe. Emerg Infect Dis. 8:7.

Becker, N., Jost, H., Ziegler, U., Eiden, M., Hoper, D., et al (2012) Epizootic emergence of Usutu virus in wild and captive birds in Germany. PLoS One 7, e32604

Buckley A, Dawson A, Moss SR, Hinsley SA, Bellamy PE, et al. (2003) Serological evidence of West Nile virus, Usutu virus and Sindbis virus infection of birds in the UK . J Gen Virol 84: 2807–2817.

Preventative measures

To minimise virus transmission, national mosquito control programs may be instigated in lands where the virus is present. For individuals, the use of topical insect repellent and other personal protective equipment is advised.

T.J. Gray, C.E. Webb. A review of the epidemiological and clinical aspects of West Nile virus. Int. J. Gen. Med., 7 (2014)

Research results

Projects

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General news

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Publications

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