Recap / Star Trek Deep Space Nine S 01 E 05 Babel
O'Brien has been having a bad day. He's been run ragged all across DS9, fixing one broken system after another. While fiddling with the main floor replicators, his day gets worse. He is infected with an aphasia virus, a disease which leaves him babbling incomprehensible gibberish. Said disease was left in a booby trap planted by Bajoran terrorists during the early construction of DS9.
And the virus is spreading, in part thanks to Quark who, with a malfunctioning replicator killing his business, decides to use a replicator in an empty set of crew quarters to provide his menu. With O'Brien suffering a heavy fever, it's become apparent this virus is fatal.
Doing a little digging, Kira traces the disease back to its creator, a Bajoran terrorist named Dekon Elig. Problem is, he's dead, having been killed trying to escape Cardassian confinement. With that lead a dead-end, she seeks out Surmak Ren, the doctor who signed Dekon's death certificate. At the first mention of the virus, he terminates connection.
Almost all of DS9 is infected, with only Sisko, Odo, and Quark unaffected. With Kira leaving to "persuade" doctor Surmak to assist her, Sisko and Odo deal with another problem: A panicking cargo captain named Jaheel attempts to leave the station. Sisko insists he can't be risked spreading the virus, but Jaheel persist and fries his ship trying to tear loose from the docking ring with the clamps still locked. Now his ship is a ticking time bomb about to take the docking ring with it.
Meanwhile, Kira has located Surmak. Beaming him straight from his office to a Runabout, Kira reveals to the good doctor that she was already infected, and so now he is infected as well. This more than convinces him to get working an an antidote.
Sisko finally gives in to the virus, leaving Odo alone at Ops. Enter Quark, who works the transporter for Odo (despite barely knowing what he's doing with it) so he can rescue Jaheel and jettison his ship before it explodes.
With that, the virus is cured and life aboard DS9 returns to normal.