A home-made cheese cultured by Neelix whose bacteria carry a virus into Voyager's bio-neural gel packs, crippling the ship in the first-season episode Learning Curve.
Brill cheese is a cheese made by Neelix in his galley aboard Voyager. It is central to the episode Learning Curve, set in 2371.
When the ship's bio-neural gel packs begin to fail one after another, the Doctor finds that they are suffering from an infection. Its source is traced to the mess hall, where Neelix has been culturing cheese from schplict milk. The bacteria in the cheese carry a virus that has spread through the ventilation into the organic circuitry, which prompts Torres to order that the cheese be taken to sickbay.
The crew cure the gel packs by giving the ship a fever, heating its systems until the virus dies. The crisis traps Tuvok with the Maquis crew members he has been drilling in Starfleet discipline.