I suspect that the origin of this conspiracy theory has much to do with the economic role which Jews played in Turkey. A similar conception of Jews as the source of all evil developed in the Ukraine in the late 19th century when that country was changing from a natural to a money economy. Jews played a middle-man role between the land-holders and the peasants and thus, the Jews came to be seen as the exploiters of the population (never mind foreign witnesses reporters that the Jews were utterly destitute and just as poor as the peasants they were 'exploiting'). 

hmm...I might just write a paper on this. If I do, Jewcy gets it first.