Sorry, I don't know. They seem to following almost everyone I follow. *gulp*. But if you find it amongst your followers on Disqus it's probably a good idea to delete it. And any other suspect accounts. People who you've never seen comment or vote - ever! Zap them now.
Click on the right hand side of your Disqus dashboard where it says 'Followers'
There you will see a drop-down list of everyone who follows you. On the left are the names, on their right is a red X. Click that and it stops that person following you.