WC of short track was cancelled in Seul, South Korea. And short track is also a part of ISU.
I doubt that in Italy it is more safe than in South Korea right now.
The event was canceled due to the fact the "authorities of the city of Seoul ordered the closing of the Mokdong Ice Rink and the cancellation of all planned competitions." ISU held their competitions despite the SARS outbreak 17 years ago, I don't think they will cancel Worlds.