An extinct species of the Delphic Expanse who, faced with sterility, engineered a mutagenic virus that rewrites the DNA of other beings, turning them into Loque'eque.
The Loque'eque appear in the Enterprise episode Extinction. Long ago an epidemic left them unable to have children, and they created a virus intended to keep their kind alive by transforming visitors to their world into members of the species, complete with instincts and fragments of memory.
In 2153 Archer, Reed and Hoshi Sato are infected while investigating a Xindi landing site. They change into ridge-faced Loque'eque, speak the old language and feel driven to find Urquat, their people's city, which turns out to be a ruin. T'Pol, shielded by her Vulcan physiology, stays with them.
Another species, which lost millions to the virus, sends containment teams to burn out every case. Phlox develops a cure with the help of T'Pol's antibodies. Archer has a sample of the virus preserved rather than letting the Loque'eque vanish entirely.