She has 'infected' everyone 'with' her enthusiasm. [=her enthusiasm has made other people feel enthusiastic too]
All the computers in the office were 'infected' by/with the same virus.
The virus has 'infected' many computers.
(..) What's troubling you? Does Gracchus have a new lover? I don't know. I thought you'd seen him. He infects everyone like a putrid fever. For the health of Rome, the senate must be bled. And he will bleed, too. Very soon. (..)2000 Gladiator