If someone blocks an infect creature, do the -1/-1 counters stay on the creature?

Question

The Infect ability is worded as follows: Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

I'm just wondering if these -1/-1 counters stay on the creature who blocked the creature with infect or do the -1/-1 counters go away at my end step?

Thanks!

Answer 1

They stay on the creature. The rules for Infect say:

702.89c Damage dealt to a creature by a source with infect isn’t marked on that creature. Rather, it causes that many -1/-1 counters to be put on that creature. See rule 119.3.

There is nothing in the rules that removes them, therefore they stay on the damaged creature.

From the Gatherer rulings on Vector Asp:

The -1/-1 counters remain on the creature indefinitely. They're not removed if the creature regenerates or the turn ends.

Answer 2

They are not removed at the end of your turn. In fact, there are very, very few instances in which the rules remove counters from objects. They are the following:

1. Dealing damage to a Planeswalker removes loyalty counters.
2. SBAs cancel out +1/+1 and -1/-1 counter pairs by removing them.
3. SBAs remove extra counters when a permanent has a limit to how many of a given kind of counters it can have.

That's it. Counters are never removed from objects except in those circumstances, or by abilities that instruct you to move or remove them. This includes the following three keyword abilities that remove counters:

• Fading (fade counter)
• Suspend (time counter)
• Vanishing (time counter)