Joshua Chelanga, Susan Chepkemei and Wincatherine Ndereba have all withdrawn from the marathon team.
Secretary general of the Kenya Amateur Athletics association (KAA) David Okeyo said: "Chelanga said he suffered serious injuries at the Boston City marathon.
"Chepkemei and Ndereba said they would prefer to run the 10,000 metres if they qualify during the trials."
Some observers suggested that the lure of running in either the Chicago or New York marathons in October and November may have been a factor in the athletes' decision.
The world championships take place in Edmonton, Canada between 3-12 August. Kenyan trials for the event are set for 21-23 June.
Okeyo confirmed that Josephat Kiprono and Kenneth Cheruiyot would run the marathon in Edmonton.
Joyce Chepchumba and Florence Barsosio will make up the women's marathon team.
Chepchumba was third in this year's london Marathon while Barsisio won the Rome evernt.
Kenya have not won marathon gold at the world championships since Douglas Wakiihuri's victory in Rome in 1987.
He went on to win Olympic silver in Seoul the following year.
