Jaxson de Ville held one of Pittsburgh's famed yellow "Terrible Towels" next to a homemade sign that read "TOWELS CARRY EBOLA" during Sunday's game.
Team president Mark Lamping said the Jaguars had no prior knowledge of the sign and will handle the matter internally.
Lamping says "improvisation and humour have both been key elements to the character of Jaxson de Ville, especially when he performs at home games. On Sunday, the person who has played Jaxson de Ville over the past 20 seasons made an extremely poor decision in that regard."
Lamping added that, "We extend our sincerest apologies to anyone who was offended."
Curtis Dvorak has worn the cat costume since the mascot's inception in 1996.
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