How will humanity survive this unique zombie virus?

This virus doesn't spread like a normal virus at all. All somebody has to do is give up on life and the infection takes over instantly. The zombies themselves hunger for flesh and blood and will stop at nothing to consume any poor unfortunate victim it can get its undead hands on.

The suicidal and the depressed are the most vulnerable to this infection and the ones most likely to become zombies.

Saliva and other fluids coming from the zombies act as depressants, so anyone coming into contact with them will feel a chemically-induced depression, triggering the infection if your will to live isn't strong enough.

How will humanity survive without the need to genocide itself?