(ORDO NEWS) — An international team of researchers has uncovered the cause of a mysterious “reeling” disease that has been killing cats in many European countries since the 1970s and occasionally affecting other mammals.
The mysterious “reeling disease” – a neurological disorder that occurs among European domestic cats – has remained a mystery to specialists for several decades.
Now a team of scientists from the Center for Clinical Veterinary Medicine at the Ludwig Maximilian University in Munich, the Friedrich Löffler Institute, the Hannover University of Veterinary Medicine (Germany), the Veterinary University of Vienna (Austria) and the Swedish University of Agricultural Sciences have been able to show that the causative agent is rubella-related virus rustrela . which causes encephalitis in many mammals.
Often, the cause of encephalitis, a group of diseases characterized by inflammation of the brain, remains unknown. It was the same with the so-called staggering disease of domestic cats, first described in the 1970s in Sweden.
It is the area near Lake Mälaren, between Stockholm and Uppsala, along with the area northeast of Vienna in Austria, that is still considered the focus of this deadly disease. Strikingly similar neurological disorders have been reported in cats in other European countries, such as Germany, and in other felines such as the lynx.
The main clinical sign of the disease is ataxia of the hind limbs (that is, impaired motor skills, impaired coordination of movements), provoking a staggering gait.
Other symptoms include an inability to retract the claws, increased sensitivity of the hard tissues of the teeth, and sometimes tremors and convulsions. In behavior, the disease manifests itself in the form of increased vocalization (screaming, meowing), depression and excessive affection with rare attacks of aggression.
The disease progresses from several days to several weeks, but can last more than a year. Usually owners and veterinarians make the tragic decision to euthanize the animal for humane reasons, since there are no effective treatments.
Although scientists assumed that the disease was caused by some kind of virus, it was not possible to accurately determine it.
For a long time, the list of candidates was headed byBorna’s disease virus is the only representative of the genus and family of bornaviruses, common among horses, sheep, cats, dogs and ostriches, as well as humans. Nevertheless, the results of the studies remained inconclusive, they were subsequently refuted.
The authors of the new work took advantage of the achievements of modern clinical metagenomics. Thanks to her new methods, in particular metagenomic analysis and reverse transcription polymerase chain reaction, they found in the brain of 28 of 29 deceased cats with non-suppurative meningoencephalomyelitis and a neurological disorder similar to “staggering disease”, traces – RNA and antigen – of the rustrela virus ( Rubivirus strelense ).
This is a recently discovered relative of the rubella virus, first identified in various mammals at a zoo in northern Germany: the animals suffered from neurological disorders and lymphohistiocytic encephalitis.
The scientists concluded that yellow-throated field mice ( Apodemus flavicollis ) played the role of possible carriers, and no signs of inflammation were found in their brain tissues. In Sweden, the rustrela virus was found only in closely related wood mice.
In the brain of local cats (from Sweden, Austria and Germany) without neurological disorders or with other types of encephalitis, which acted as a control group, the rustrela virus was not found.
And the DNA of the Borna virus was not seen in the samples of the pets who died from the “reeling disease”: thus, the hypothesis that BoDV-1 is the causative agent of this mysterious disease was again refuted.
As shown by phylogenetic analysis, rustrela virus genomic sequences from three regions belong to separate genetic clusters, with the Swedish and Austrian samples being more closely related to each other than to the German ones.
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