Gazi was reported for bowling with a suspected illegal action during the One-Day International series, which Bangladesh lost 3-0.
Left-armer Sunny, who has played four Tests, replaces him ahead of the opening match in St Vincent, which begins on 5th September.
"The National Selection Panel has named left-arm spinner Mohammad Elias as replacement for off-break bowler Shohag Gazi in the Bangladesh squad for the two-match Test series against the West Indies. Elias will leave Dhaka tomorrow (Tuesday, 02 September) evening," a Bangladesh Cricket Board (BCB) statement confirmed.
"Gazi, who will undergo testing for suspected illegal bowling action, returned to Dhaka today morning from the West Indies along with Masrafe Bin Mortaza, Abdur Razzak, Taskin Ahmed and Mohammad Mithun."
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