Virus?

This post is about a couple of rats I had about four years ago. Both of them died very young and suddenly, and I was wondering if anyone else had experienced the same kind of thing.
I had had them about two months (I got them in Petmania) and they were probably six or seven weeks old when I bought them. They had both been fine in the morning but when I came home from school one of them (ginny) was unable to move and really cold. She was still alive but only just. We took her to the vet immediately and I noticed on the way that she would have periods where she jerked about, almost like a seizure, and then lay still again. The vet didn't know what was wrong but it was clear that she wasn't going to make it so we had her put to sleep. They offered an autopsy but I was quite young and I didnt realise that it might be useful so I said no. That night her sister was fine but the next day when I came home from school she was in the exact same condition as Ginny had been the night before. We decided not to bring her to the vet (which I regret now as she was probably in pain) and I tried to keep her warm and fed her with a dropper, but she died fairly soon. Like Ginny she had several little 'seizures'. Sorry for the essay but I just wanted to know had this happened to anyone elses rats before?

P.S. I threw out all of their old toys and completey sterilised the room, and also left it several years before I got other rats, so if it was a virus it's not here anymore

Does sound like a virus. Not sure what virus though, hard to say... I don't know of any that cause seizures, off the top of my head! :/ perhaps SDA or Sendai?

xx