Board Thread:General Discussion/@comment-6192846-20130929130231/@comment-12148883-20130929191002

Irina intended to spread HERS through the Venom Sword's powers. That's why she helped Venomania: Because apparently the chances of someone with HERS being born increased a lot in the harem girls, as a result of the demon of lust powers.

In the end, Meilis, Lukana and Mikulia's sons had HER.

Not sure if there's anything more about the disease itself, though...