Abstract and Introduction
During late summer 2001 in Austria, a series of deaths in several species of birds occurred, similar to the beginning of the West Nile virus (WNV) epidemic in the United States. We necropsied the dead birds and examined them by various methods; pathologic and immunohistologic investigations suggested a WNV infection. Subsequently, the virus was isolated, identified, partially sequenced, and subjected to phylogenetic analysis. The isolates exhibited 97% identity to Usutu virus (USUV), a mosquito-borne Flavivirus of the Japanese encephalitis virus group; USUV has never previously been observed outside Africa nor associated with fatal disease in animals or humans. If established in central Europe, this virus may have considerable effects on avian populations; whether USUV has the potential to cause severe human disease is unknown.
Usutu virus (USUV) is a relatively unknown member of the mosquito-borne cluster within the Flavivirus genus, closely related to important human pathogens such as Japanese encephalitis virus (JEV), Murray Valley encephalitis virus (MVEV), Dengue virus (DENV), Yellow fever virus (YFV), Saint Louis encephalitis virus (SLEV), and West Nile virus (WNV).[1,2,3] Isolated for the first time from mosquitoes in South Africa in 1959 and named after a river in Swaziland,[4] USUV was sporadically isolated from several mosquito and bird species over the next decades.[5,6,7] Only two isolations have been reported from mammals, one from Praomys sp. (African soft-furred rats) and one from a man with fever and rash.[5] The virus has never been associated with severe or fatal diseases in animals or humans, and it has never before been observed outside tropical and subtropical Africa.
From the beginning of August through mid-September 2001, a considerable die-off of Eurasian Blackbirds (Turdus merula) was observed in and around Vienna, Austria. Some observers reported obviously sick blackbirds, which showed signs of apathy and ruffled plumage. Within 5 days in mid-August, five Great Gray Owls (Strix nebulosa) died in the Tiergarten Schönbrunn Vienna Zoo. In addition, many dead Barn Swallows (Hirundo rustica) were observed in the Austrian federal state of Upper Austria, 200 km west of Vienna. Investigating this episode of avian deaths in Austria, we determined USUV as the causative agent.
Emerging Infectious Diseases. 2002;8(7) © 2002 Centers for Disease Control and Prevention (CDC)
Cite this: Emergence of Usutu virus, an African Mosquito-Borne Flavivirus of the Japanese Encephalitis Virus Group, Central Europe - Medscape - Jul 01, 2002.
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