If you are playing particularly junglers that are susceptible to counter jungling, you can not stop them by yourself. This is why depending on where you at, people are supposed to help you.
For example, if you are purple side and get counter jungled at your red, mid and Top should try and come help. After your first back, always have a ward or two and place them at the entrance of your jungle.
For example, on purple side, ward dragon and it will ward the entrace to your blue buff. On your red, either ward it at the entrace of wraiths, or just ward your red buff as a whole. You don't particularly have to cover alot of spots with your wards, so just play the wards in the brush near your buffs and you will see when they try to steal it.
But yes, without your team helping you, you can not stop them. So if you have a bad team with no map awareness or team spirits, you are pretty much screwed. Make sure to ping the counter jungler every time they are in your jungle fighting your buffs/you so your teammates see it because some people, believe it or not, have really bad map awareness.