Infected on collision

I have a question. Suppose Im making a Zombie game. I have two Sprites: Zombie and Human.

At the start of the game there is 1 Zombie. There are many humans. When that Zombie collides with a Human, the Human becomes infected (a Zombie himself).

Now that Human that just became infected it can also infect Humans. How would I do this in Construct 2?

Ideally I would like to change the Sprite of Zombie to Human. In Construct 2 I cannot check for a collision between a Human (with infected = "true") and a Human (with infected = "false").

I have now achieved this by destroying the Human and spawning a Zombie, but this is not really pretty.

Thanks!

This should help; you'll be able to check for variables when Humans collide with each other after this tutorial.

scirra.com/tutorials/556/understanding-picking-with-respect-to-families

That is exactly what I need. You are awesome!

Here is an old demonstration where you can see the exact mechanic:

Evil sprites

Thanks a lot for the example!