Evidence of Borna disease in horses in Iceland

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An Icelandic horse in full winter coat near Krýsuvík. Photo: Andreas Tille/Wikipedia
An Icelandic horse in full winter coat near Krýsuvík. Photo: Andreas Tille/Wikipedia

Researchers have found the first evidence of potentially deadly Borna disease in horses in Iceland.

Blood tests revealed antibodies against Borna disease virus in four of five horses showing neurological signs in a stable in northern Iceland.

Borna disease is an infectious neurological syndrome that can affect warm-blooded animals, including horses and humans. It can also affect cattle, sheep and dogs.

The name is derived from the town of Borna in Saxony, Germany, which suffered an epidemic of the disease in horses in 1885.

The mortality rate can reach 80-100 percent in infected horses.

The Icelandic scientists, whose findings were reported in the journal, Acta Veterinaria Scandinavica, said the stabled horses had shown clinical signs, including poor coordination and reduced appetite, leading to euthanasia of one of the horses.

Tests revealed no evidence of active equine herpes virus 1 infection, a common source of central nervous system disease in horses, nor equine arteritis virus and West Nile virus.

However, blood tests revealed antibodies against Borna disease virus in four of the horses.

The researchers said it was the first evidence of antibodies to the virus in Iceland.

“Whether Borna disease virus was the cause of the neurological signs could, however, not be confirmed by pathology or molecular detection of the virus.

“As Iceland has very restricted legislation regarding animal imports, the questions of how this virus has entered the country and to what extent markers of Bornavirus infection can be found in humans and animals in Iceland remain to be answered.”

The researchers said the virus transmission routes for Borna disease virus were still obscure, but the involvement of reservoir hosts, such as wild birds, rodents and insectivores, had been proposed. They raised the possibility that the disease might have arrived with migratory birds.

“Most cases of equine Borna disease have been reported from Central Europe; however, Borna disease virus infection markers have been reported all over the world.”

The scientists said the affected horses were stabled in an isolated fishing village in northern Iceland.

They reported there was a cluster of twelve stables that housed 70–80 horses during the winter. In February 2011, one of the stables, with eight horses, reported neurological signs in five horses, starting in a 21-year-old gelding.

The researchers said that as antibodies to both Borna disease virus and Avian Bornaviruses (ABV) could cross-react in the testing method used, they could not exclude the possibility that the virus circulating in Iceland could be ABV or a more avian-like Bornavirus.

The researchers were Sigríður Björnsdóttir, Elfa Agustsdóttir, Anne-Lie Blomström, Inga-Lena Örde Öström, Louise Treiberg Berndtsson, Vilhjálmur Svansson and Jonas Johansson Wensman.

Sigríður Björnsdóttir, Elfa Agustsdóttir, Anne-Lie Blomström, Inga-Lena Örde Öström, Louise Treiberg Berndtsson, Vilhjálmur Svansson and Jonas Johansson Wensman.
Serological markers of Bornavirus infection found in horses in Iceland
Acta Veterinaria Scandinavica 2013, 55:77 doi:10.1186/1751-0147-55-77

The full report can be read here http://www.actavetscand.com/content/55/1/77

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