Pure Hair causing Fireflies in Luxrender

Catani

I have been trying to use any of the "Pure Hair" products in luxrender (I use the Reality Plugin 2.5 and DAZ Studio 4.6) but they always produce ridiculous amounts of fireflies which won't go away with time but get worse.
I read that sometimes the materials are just to shiny so I played with the settings and it turned out that the fireflies mostly occur when I use a blond or white hair texture. When I use brown hair there are much less fireflies though still present.
Additionally the fireflies seem to be connected to the transparency map. When I don't use the transparency map there is no trace of fireflies whatsoever.
And that confuses me. I looked at the transparency map and I couldn't find a significant difference to e.g. the transparency map of the "Zac Hair" which works just fine.
The specular settings seem to have no influence on the occurrence of fireflies at all.

Can anyone explain this to me or better yet tell me how to fix it?
Surely it must be possible to use the "Pure Hair" products with a blond texture and the necessary transparency map?

Thank you in advance.