User blog comment:AnimalKirby/Gore Magala Discussion/@comment-2040723-20121012172758

I found a picture of a translated demo manual online that explains how the Feral Wyvern Virus (as it's called in this translation) works. The picture is right here. http://i.imgur.com/j1byg.jpg

It's a little hard to read, so I'll paraphrase what it says.

Apparently, the virus can spread to other monsters (like the Tigrex in the TGS demo), and if an infected monster attacks you, it'll infect you as well. The infection doesn't have an immediate effect; instead, it causes a bar to appear under your name and fills over time. When the bar is full, passive healing is disabled- an item called a Nulberry can slow the bar, but it won't stop it from filling. However, if you deal enough damage to the monster that infected you, yu'll enter a state called "Synergy" that cures the virus and grants a large bonus to Affinity in the process.