Dialog under "spreading epidemic" is fine as it's last quest: "You have done all that you can for now. I shall send warning to Necrom, the Holy City of the Dead, and report that a cult of Molag Bal has been discovered. But first, I should reward you: please, take this staff, my child.".

Journal entry for it says otherwise: "Ratagos thanked me for ending the epidemic in Ranyon-ruhn. He then revealed the true nature of that which he faces here in the Telvannis Region: a cult of Molag Bal! He told me I must go to Necrom as soon as possible and report this to the Temple leader there."

Either change that entry as he didn't send PC to Necrom, or make it proper quest stage with reporting to "TR_m2_Alvu Sareleth" for some faction rep. There is never too much content for Necrom.