Do bittorrent files contain viruses?

Much like Lime- and FrostWire, if you use it stupidly you will get a virus.
If you use the big ol' organ in your skull you won't.

In other words: it's not the programs fault you got the virus, it was /yours./
Yes, some do contain viruses but not every last one.

Besides, if you had a good anti-virus program, you shouldn't worry at all about viruses.

Limewire has been known to have far more viruses than frostwire. I am surprised, however, that you did get a virus using Frostwire. In my opinion, you cannot escape viruses entirely when downloading stuff off of these services. Just be sure to scan everything before you open it and you should be safe. I recommend using Nod32 for your virus software.