Turan as well as Sergio Busquets and Andres Iniesta all came down with the flu earlier in the week but the bearded winger was hardest hit and will miss the clash against Bilbao at the Camp Nou.
The Turkish international winger had featured in all six games since making his debut for Espanyol in the Spanish Cup Last 16 first-leg game all of which have ended in victories.
Bacelona have scored 20 goals while conceding just three since Turan made his first appearance for the club and he has two assists to his name.
The reigning Copa del Rey champions beat Bilbao 2-1 in the first-leg at the San Mames.
Barcelona’s squad announced for Wednesday’s game:
Marc-Andre Ter Stegen (goalkeeper), Jordi Masip, Gerard Pique, Ivan Rakitic, Sergio Busquets, Dani Alves, Andres Iniesta, Luis Suarez, Lionel Messi, Neymar, Javier Mascherano, Marc Bartra, Munir, Sergi Roberto, Adriano Correia, Aleix Vidal, Thomas Vermaelen and Jérémy Mathieu.