Usutu virus

USUV was first identified by Bruce McIntosh in Culex neavei mosquitoes in South Africa in 1959,[2][3] and is named after the Usutu River.

Since 1996, it has also been found in European countries, including Austria, Belgium, Croatia, Czech Republic, Denmark, France, Germany, Greece, Hungary, Italy, Serbia, Spain and Switzerland, and more recently the Netherlands, and was spreading across Europe in the late 2010s.

In addition to humans, the virus has been isolated from Pipistrellus bats, and anti-USUV antibodies have been found in horses, dogs, deer, wild boar, rodents and shrews.

[10] Two cases of symptomatic infection in humans have been reported from Africa, with fever and skin rash but no neurological symptoms.

In Europe, 46 infections were detected up to 2019; these were mainly asymptomatic, but neurological symptoms including encephalitis and meningoencephalitis have been observed.

[3] The virus is highly pathogenic in birds, causing central nervous system symptoms, enlargement of the liver and spleen, and infiltration by inflammatory cells in a wide range of organs.

Immunohistochemistry (IHC) of USUV-uninfected (A, C) and –infected (B, D, F and F) blackbird organs using an USUV-specific murine monoclonal antibody.
(A) USUV-uninfected blackbird brain.
(B) USUV-infected blackbird brain showing a group of USUV-positive neurons (in red).
(C) USUV-uninfected blackbird heart.
(D) USUV-infected blackbird heart, USUV-positive cells are localized in the endocardium (in red).
(E) USUV-infected blackbird liver, disseminated USUV-positive Kupffer cells (in red).
(F) USUV-infected blackbird lung, disseminated USUV-positive cells (in red).