Until now, no one knew why pythons and boa constrictors would sometimes tie themselves up in knots, stare into space and appear drunk.

Now scientists believe the fatal condition, known as inclusion body disease (IBD), is caused by a rodent virus. It can hit aquariums hard by infecting a large number of snakes before it's identified, and, with no treatment available, sick snakes must be euthanized.

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Researchers from the University of California at Irvine noticed signs of the virus in DNA samples of snakes during an outbreak of IBD at the Steinhart Aquarium in San Francisco, according to a study published in mBio. When they tested the samples, they found a virus never seen before.

The virus appears to belong to a family of arenaviruses usually seen in rodents, and before now, only in mammals. But the snake virus doesn't fit into the two categories (called New World and Old World) previously known.

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"This is one of the most exciting things that has happened to us in virology in a very long time," University of California at Irvine professor Michael Buchmeier said in a press release. "The fact that we have apparently identified a whole new lineage of arenaviruses that may predate the New and Old World is very exciting."

With the new findings, aquariums should be able to test snakes for the virus before exposing them to other snakes.

Researchers became interested in the problem when a San Francisco Bay Area woman named Taryn Hook wrote a letter after becoming worried about her snake, a 7-foot-long boa constrictor named Larry, NPR reports.

"So I wrote him a letter with a picture of myself and Larry in our backyard," Hook told NPR. "And I pled with him, explaining that he was my last hope."

Hook explained that the problem went beyond Larry to aquariums and zoos.

The virus also contains a gene closely related to a gene in the ebola virus, which may help research on how viruses switch from species to species and eventually infect humans, reports Wired UK.

Photo: A python. Credit: iStockPhoto