Researchers from the University of California at Irvine found that Inclusion Body Disease (IBD), strikes captive pythons and boa constrictors causing them to display strange behaviour, such as 'stargazing' - staring upwards for long periods of time, the Daily Mail reported.
Other symptoms include appearing drunk and getting into a legless tangle.
"They tie themselves in a knot and they can't get out of it," said snake expert Professor Michael Buchmeier from the University.
IBD gets its name from inclusions, or pockets of foreign material, found in the cells of affected animals. Although the disease is known to be highly infectious, its cause has been a mystery until now.
Researchers led by Buchmeier investigated an outbreak of IBD among snakes at the Steinhart Aquarium in San Francisco, California.
The study identified signs of an unusual virus in DNA samples from a number of affected boas and pythons.
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Tests showed it belonged to a family of arenaviruses - a type of virus that normally infects rodents.
The virus did not fit neatly into either of the two known categories of New World and Old World arenaviruses.
"The fact that we have apparently identified a whole new lineage of arenaviruses that may predate the New and Old World is very exciting," Buchmeier said.
Finding the virus in snakes was another surprise twist, previously arenaviruses had only been known in mammals.
Arenaviruses usually infect mice and rats, but can cause haemorrhagic fever in humans.
The study was published in mBio, the journal of the American Society for Microbiology.