A new disease that can kill both domestic and wild cats has been discovered for the first time in the United States. This variant of the rustrela virus, called RusV, was identified in a female mountain lion in Douglas County, Colorado, according to a study published in the journal Emerging Infectious Diseases. RusV is related to the rubella virus, known for causing a skin rash in humans, but affects cats with severe neurological symptoms.
Discovery and symptoms of the disease
The infected mountain lion was first observed in May 2023 with symptoms including lesions on her skin, severe muscle weakness in her hind legs, reluctance to move, and decreased mobility. Wildlife officers suspected the presence of a disease but were uncertain of its nature. To alleviate her suffering and prevent further damage, the mountain lion was tranquilized and euthanized.
Researchers then began investigating the potential cause of the unknown disease. Through genetic sequencing and analysis of tissue samples, they identified the presence of RusV, also known as Rubivirus strelense. This virus is the cause of “staggering disease,” a neurological syndrome that is typically fatal in cats. The disease presents with lesions and limb impairment, which were observed in the mountain lion.
Linking RusV to staggering disease
To establish a connection between the symptoms and RusV, researchers employed hybridization methods, which involve the binding of complementary strands of DNA or RNA. This technique allowed them to identify specific genes and analyze levels of messenger RNA (mRNA), which carries genetic information necessary for protein production.
Their findings showed that RusV RNA was present in all regions of the mountain lion’s brain and nearly all levels of her spinal cord.
The study revealed particularly high levels of the virus in the granule cell layer of the hippocampus and Purkinje cells of the cerebellum. These findings were similar to those seen in staggering disease cases in cats from Europe.
RusV’s presence and potential spread
The novel RusV virus identified in Colorado was compared with other strains and found to be genetically similar to known sequences in Europe. This suggests a potential link between the outbreaks. However, scientists are currently unsure how widespread RusV is among domestic and wild cats in the United States.
The American Veterinary Medical Association has warned pet owners to look out for symptoms such as a staggering gait, inability to retract claws, extreme sensitivity to touch, tremors, and seizures. The illness can last from a few days to over a year, but typically results in a decline that necessitates euthanasia.
Concerns about the disease’s spread
While researchers like Dr. Karen Fox, a wildlife pathologist at Colorado State University and study author, are not immediately concerned if this case is isolated, they remain cautious. Dr. Fox explained to National Geographic, “When we find diseases, it means you’re the tip of an iceberg, and there’s a bunch more you’ve missed over time.”
Given the potential severity of the disease, monitoring for additional cases and understanding the virus’s spread are crucial for protecting both domestic pets and wildlife.