West Indies lose veteran for semi-final due to Covid-19
Young all-rounder Mandy Mangru - who has been in New Zealand as a travelling reserve - has been drafted into the squad as Fletcher's replacement and is in contention to play her first game of the tournament.
The loss of Fletcher reduces West Indies' bowling options against the powerful Australia line-up and robs them of an experienced player that has played 58 ODI games for the Caribbean side.
Fletcher has picked up four wickets from three matches at the ICC Women's Cricket World Cup, with her best haul coming against Bangladesh when she collected 3/29 from 10 overs in Mount Maunganui.
Mangru has played just one ODI for West Indies and that came in the lead-up to the World Cup when she won a debut against South Africa in Johannesburg last month.
The 22-year-old scored 15 runs batting at number six on that occasion and registered bowling figures of 0/15 from three overs with her handy off-spin.