I wouldn't worry about diseases in a lab/breeder rat. The only thing I'd suggest is making sure you are up to date on your tetanus shot, but honestly if the skin wasn't broken you probably don't even need to consider that.
yikes. I haven’t gotten a tetanus shot in years. Many many years actually. It was more of a scratch. It did break the skin a tad. But didn’t bleed at all. It was a bite though. Not a scratch.