New virus causing ‘staggering disease’ discovered in US – and it can kill domestic and wild cats
A disease that can kill cats, both domestic and wild, has been discovered for the first time in the United States.
A variant of the Rustrela virus — related to the better-known rubella virus that causes a rash in humans — called RusV was discovered in a female mountain lion in Douglas County, Colorado, last year, according to a study published in the journal, Emerging infectious diseases, this month.
The big cat was observed in May 2023 with lesions on its skin and signs of severe muscle weakness in its hind legs. It was also reluctant to stand up and had reduced mobility.
Wildlife officials suspected the puma was suffering from an illness, but were unsure what was causing its behavior. To end its suffering and prevent brain tissue destruction, the big cat was tranquilized and shot in the chest.
The study authors then began working to investigate the potential cause of this unknown disease.
Scientists said studies of tissue samples, the cat’s history and genetic sequencing suggested she had the Rustrela virus variant, RusV. Rubivirus strelenseRusV is the cause of what is called “stunning disease.”
Staggering disease is a typically fatal neurological syndrome in cats, the study noted, and RusV was only recently identified as its cause. The animals show signs of lesions and the same limb deficiency.
This syndrome has been observed in domestic cats in Europe since the 1970s and has also been observed in rodents. A similar syndrome was reported in Alabama cats 45 years ago, but the cause was obscure.
To demonstrate a link between the lesions and RusV, the researchers used hybridization methods already developed for the virus. Hybridization is the process by which two complementary molecules of single-stranded DNA (the hereditary material of humans and almost all organisms) or RNA (ribonucleic acid) bind together. RNA is a nucleic acid present in all living cells and has similarities to DNA.
Hybridization allows specific genes to be identified and the levels of the messenger RNA molecule (mRNA) to be analyzed in cells. mRNA molecules carry the genetic information needed to make proteins, which perform many essential functions in the body, such as repairing cells and protecting the immune system.
The authors said these methods showed that RusV RNA was present in all regions of the big cat’s brain and at nearly all levels of the spinal cord.
“We found particularly abundant or large, dot-like signals in the granule cell layer of the hippocampus and in the Purkinje cells of the cerebellum, similar to findings from cases of staggering disease in cats from Europe,” said the researchers from the Friedrich-Loeffler-Institut in Germany.
The new RusV virus discovered in Colorado was compared to other strains. It was revealed that the Colorado samples belonged to genetic sequences known in Europe.
Scientists do not yet know how widespread the virus is among domestic or feral cats in the United States.
According to the American Veterinary Medical Association, symptoms to watch for include a staggering gait, inability to retract claws, extreme sensitivity to touch, tremors and seizures. The condition typically lasts a few days to a few weeks, but can persist for more than a year.
This usually results in a decline that requires euthanasia of the animal.
“We’re not concerned that this is an isolated case,” said Dr. Karen Fox, a wildlife pathologist at Colorado State University and an author of the study. National Geographic“But traditionally, when we discover diseases, it means you’re just the tip of an iceberg, and there are many more that you’ve missed over time.”
