WEDNESDAY, July 8, 2015 (HealthDay News) -- After the mysterious deaths of three German variegated squirrel breeders, researchers have identified a deadly new virus that can be transmitted from variegated squirrels to humans.
But you don't need to be concerned about the squirrels scurrying across your path every day. Variegated squirrels are an exotic breed native to southern Mexico and Central America.
"A new bornavirus that can be transmitted to humans and cause severe disease has been detected in variegated squirrels. The study shows that exotic animal species can have the risk of transmitting novel zoonotic viruses to humans from close contact," said the study's senior author, Dr. Martin Beer, head of virus diagnostics at the Friedrich-Loeffler Institute in Insel Riems, Germany.
Dr. Marc Siegel, a professor of medicine at NYU Langone Medical Center in New York City, said that based on these few cases, the general public should not be concerned about this new virus.
"It's likely that bornavirus, commonly found in horses and sheep and capable of causing neurological symptoms, was present in the squirrels that scratched these men, causing the neurological and behavioral symptoms," he said.
"It is possible that this virus could spread to squirrels here in the U.S. and occasionally to humans, but we wouldn't see sustained spread, as there is no evidence of spread from human to human," Siegel said.
Details of the findings were published in the July 9 issue of the New England Journal of Medicine.
The three squirrel breeders were diagnosed with encephalitis -- inflammation of the brain -- and died within two to four months of developing symptoms, the study reported.
The three deaths occurred between 2011 and 2013. Analysis of the squirrels and the victims' brains found that this previously undetected virus was present in both the animals and the humans.
Beer said that the three men were in their 60s or older and had other medical conditions that possibly could have contributed to their reaction to the virus.
The three men were friends, and all were members of the same squirrel-breeding association, the researchers said. And, at least two of them were known to have been scratched by their squirrels, and one had been bitten, according to the study.
Symptoms of the virus can include fever, shivers, and low energy, according to the study. Symptoms of encephalitis include clumsiness, an unsteady walk, confusion, disorientation, drowsiness, irritability, sensitivity to light, stiff neck and vomiting, according to the U.S. National Institute of Neurological Disorders and Stroke.
"These findings indicated that the virus most likely caused the lethal human infections and should be considered as a novel zoonotic virus that was transmitted from infected squirrels," Beer said. "Zoonoses are infectious diseases that can be transmitted between animals and humans," he said.
The infected squirrels showed no signs of the infection and the cause of infection is still unknown, he said. Whether the animals contracted the virus in the breeding facility or brought it with them from Latin America isn't known. "Bites or scratches are a likely route of transmission," Beer said.
Analyses showed that this virus, named variegated squirrel 1 bornavirus (VSBV-1), is separate from the other known bornavirus species, he said.
"However, there is, up to now, no indication that other squirrel species can also be infected, and there are no further human cases reported," Beer said.
For more on encephalitis, visit the U.S. National Institute of Neurological Disorders and Stroke.