Virus Detection

Hi i have a 100 client network the problem i have is i take of my antivirus server because the hard drive crash and the same day during the server instalation some user introduce a virus in the network …. nobody nows who but all my network still infected after that , with this virus Net-Worm.Win32.Kido.ih and i don’t know who is the sourse … how i know that how can i delete that virus of my network…