"Kirui informed us that he is injured, while Wilson told us he has a commitment around that time," said Athletics Kenya Vice-President Paul Mutwii,
Kirui, who has won the last two world titles, in 2009 and 2011, has a stress fracture in his right shin and will be out for six weeks.
Kipsang, the 2012 London marathon champion, will run at a yet-to-be disclosed city marathon around the time of the world championships, Mutwii said.
"We have therefore brought on board Mike Kipyego, who won the Tokyo marathon last year, 2009 world half marathon silver medallist, Bernard Kipyego, and Bernard Koech, and Paris marathon winner Peter Some as a reserve," Mutwii added.
World champion Edna Kiplagat will lead the women's line up, along with London marathon winner Priscah Jeptoo, and Lucy Kabuu. Margaret Akai is the reserve.
Kenya will name the final team for the world championships during trials next month.
- Athletics, Track & Field
- Bernard Kipyego