The Teplan blight was a disease created by the Dominion and used against the Teplans by the Jem'Hadar. The disease is also known as the "Quickening" after the end stage in which the disease quickens before the patient dies.
In 2372, Julian Bashir encountered the Teplans and attempted to find a cure for the blight. Trevean, a Teplan doctor, was doubtful of Bashir's efforts and Bashir also suffered a setback when he discovered that the electromagnetic fields from his Starfleet medical equipment accelerated the disease. While Bashir was not able to cure the Teplans currently suffering from the disease, but instead discovered an antigen that could be used to inoculate children while in the womb and prevent them from developing the blight. After returning to Deep Space 9, Bashir continued to work on a cure for the Teplans still suffering from the disease. (DS9 episode: "The Quickening")
At a conference on Romulus in 2375, Bashir gave a seminar on the Teplan blight to Federation and Romulan attendees. Tal Shiar Chairman Koval expressed interest in the Quickening, which alarmed Bashir but not Luther Sloan of Section 31. (DS9 episode: "Inter Arma Enim Silent Leges")