OK, first question is - how old is that leaf? Did it just emerge or has it been out for a while and other normal leaves followed? I see this sometimes on Alocasias that are stressed - usually one leaf comes out like that and if the stress is corrected, the next leaves come out fine.
IMHO, If it is a virus, it is not the really nasty one that would distort the leaf as well as discoloring it.
LariAnn
