A statement from British Cycling said Armitstead, who won silver in the omnium in last year's Championships, was responding well to treatment but would not be fit in time for the event, which start in Apeldoorn, the Netherlands from March 23.

The 22-year-old Otley rider's season has already been undermined by a gall bladder infection that required a stay in hospital.

Trott will thus make her debut in the event, and may also appear in the team pursuit.

Fellow 18-year-old Sam Harrison and 20-year-old Dani King are also in with a chance of making World Championship debuts.

Trott's major championship debut at the Delhi Commonwealth Games in October saw her finish seventh in the 3,000 metres individual pursuit and ninth in both the Points and Scratch races.

"I did not realise how big the step up was," said Trott, who had secured gold in the omnium and silvers in the points race and individual pursuit event at the previous month's World Junior Track Championships.

"My performance in the Individual Pursuit was what I was most pleased with as I knocked four seconds off my PB."

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