Rigelian fever
Rigelian fever was a gram-positive pathogen originating from the Rigel system. The only known cure for this fever was the rare mineral ryetalyn.

In 2152, Crewman  came down with Rigelian fever after a visit to Tessik Prime, causing Doctor Phlox to inoculate the entire  crew before an outbreak occurred. This would eventually save the life of a crew member, though not in the way intended: after Travis Mayweather was kidnapped by an automated repair station hoping to use his brain functions to enhance its capabilities, throwing the crew off by creating a near-perfect "dead" , the complete absence of the vaccine in his bloodstream (the supposed cause of death would've actually strengthened it) proved that the corpse in sickbay was not the real Mayweather, allowing Archer and T'Pol to rescue him before the brain damage incurred by the station was irreversible. ()

In 2154, a sample of this disease's pathogen was stored at Cold Station 12 for study. Malik identified this as one of the most dangerous pathogens kept at the station and transferred them aboard his Bird-of-Prey for "a little insurance." ()

In 2269, there was an outbreak aboard the Federation starship . Twenty six crewmen became infected; three died. With her entire crew imperiled, the ship went to the planet Holberg 917G for its natural ryetalyn deposits. These however were laced with irillium, which if not removed negates the antitoxic effectiveness of ryetalyn. The former immortal Flint, master of Holberg 917G, was told of this fever's similarity to Bubonic plague and recalled the horror at Constantinople in 1334. ()

Apocrypha
Rigelian fever (spelled "Rigellian" fever, though) was a plot device in two of the twenty story arcs in the Star Trek newspaper comic strip

de:Rigelianisches Fieber
ja:ライジェル熱
Medical conditions