Infected host on guest network

[Dave]

So i'm going through the security checkup report and notice there are 2 infected hosts identified that were connected to our guest network.

I can't really see who they are, but it could be potentially an employee that connected to the guest network for some reason and will connect again to the corporate at some point in time.

How do you guys deal with these kind of issues, or which measures should and can i think so theses hosts don't infect other machines on the corp network?