In 2009, some of the snakes at the California Academy of Sciences' Steinhart Aquarium were acting sort of s-s-s-s-strange. Scientists suspected a sickness whose cause was mysterious. Now researchers think they’ve found an unlikely origin, as they watch the disease play out in strange and terrible fashion.

"Some of the symptoms are pretty bizarre," said Michael Buchmeier, a professor of infectious diseases at the University of California, Irvine, in a recently issued statement about the illness. Sometimes the sick snakes look "like they're drunk" or engage in "stargazing," staring up into space. Other times, "they tie themselves in a knot, and they can't get out of it," he noted.

The behavior might sound silly, but the underlying disease is quite serious for zoos and other collectors. The illness is part of a broadly described "inclusion body disease," which can spread among captive boa constrictors and pythons, causing protein buildup, bacterial infections and, eventually, body wasting. "It's a devastating disease," Joe DeRisi, chair of the biochemistry and biophysics department at University of California, San Francisco, said in a prepared statement. "It's essentially fatal every time." Snakes diagnosed with the disease are usually killed.

After an outbreak of the disease at the academy and reports of a sick snake from a pet owner in San Jose, Calif., a team of researchers became determined to apply new genetic technology called Virochip, which usesR DNA microarray scanning to hunt for a suspect. The researchers first sequenced the genome of a healthy boa constrictor so that they could sort out boa genetic material from that of an infection. They then sampled some of the sick snakes using the microarray. What they found surprised them: A type of virus, arenavirus, that appears to be a distant—and perhaps ancient—relative to the viruses that can cause Ebola and hemorrhagic fever in humans. This type of virus was previously unknown to infect reptiles. The researchers found two strains of it in the sick snakes and were able to culture them in cells taken from another boa to further support the genetic results. The findings were published online this week in the journal mBio.

"This is one of the most exciting things that has happened to us in virology in a very long time," Buchmeier said. "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 discovery might provide new information about the evolution of these viruses and possibly insights into the mammalian versions. The infection has never been documented to spread to humans, but the new findings might also help veterinary scientists work toward a cure or prevention for the snake-striking variety. Hopefully, the study authors noted, "surveillance by veterinarians will one day lead to adequate control of this previously vexing condition." And perhaps someday, the snakes will knot no more.