One of the oddest behavior biologists have witnessed is Inclusion Body Disease (IBD) – a fatal disease that affects captive pythons and boas causing them to tie themselves in knots they can’t untangle out of. The source of this extremely erratic and suicidal behavior was unknown until recently when researchers have found it is caused by a viral infection. Specifically, it’s a type of arenavirus that can’t be categorized in any of the two known categories of New World and Old World arenaviruses. More importantly, this is the first time scientists have found that an arenavirus can infect non-mammalian organisms.

‘This is one of the most exciting things that has happened to us in virology in a very long time,’ said snake expert Professor Michael Buchmeier, from the University of California at Irvine.

‘The fact that we have apparently identified a whole new lineage of arenaviruses that may predate the New and Old World is very exciting.’

The bizarre condition apparently has only been observed in captive snakes. It causes boas and pythons to move erratic, often as if they’re in a drunken state, and sometimes to get in a tangle they can’t escape after. Also, IBD also causes the snake to become stargazed – looking upward for long periods of time. Yup, these are some crazy snakes!

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The researchers investigated an outbreak of IBD at the Steinhart Aquarium in San Francisco, California. After analyzing DNA samples, the researchers uncovered unusual signs that tell of the presence of a virus. Further testing revealed the virus belong to a family called arenaviruses, which typically infect rodents. It’s most likely that the snakes become infected by diseased rats on which they fed. This is the very first time  an arenavirus has been found to infect non-mammalians.

IBD was documented in a paper published in the journal mBio.