Severus was feeling magrinally better, but the illness was the reason it had taken him several days to respond the the initial inquiry. At least now he could hold a quill without seeing double vision. However, upon seeing Goldstein's owl, he was less than pleased. It had seemed like Dragon Pox, but the symptoms had been all wrong.
Between this and the information he had gleaned from Harry, he knew beyond a shadow of a doubt who had caused this.
Goldstein, Your blood will indeed serve as a base for finding some sort of antidote. I will speak with Oliver shortly as he is working as my apprentice at present and I will see what we both will come up with.