Dula Seng was a female Trill who lived on the planet Trill in the 24th century. She was born around 2365 and had at least one older brother, Dapo.
In early October 2376, Dula and her brother were taken to the Najana Library in Leran Manev by their mother. While they were inside, a riot broke out on the streets outside, instigated by a neo-Purist radical group. Seng got Dula and Dapo outside and tried to get them home but they were caught up in the crowds where they were sprayed with an anesthezine-containing crowd-control gas. Both Dapo and his mother had allergic reactions to the gas which affected their breathing and mobility, but they managed to get to Manev Central Hospital, however they were turned away.
A little while later, they were found by Doctor Julian Bashir and Asal, a Trill police officer. Dula told Bashir what had happened to them and, after he had treated Dapo and her mother with lectrazine, she thanked him for helping them. (DS9 - Worlds of Star Trek: Deep Space Nine novel: Trill: Unjoined)