Jay, usually the incubation period for viruses and bacteria is about 5-7 days in a rat. If you went to a pet store or anything and handled their rats or even went near their small pets, it's important to know.

Even if you step in squirrel crap outside, they carry SDA virus, which can kill your rats if the secondary infection doesn't kill them first.

It's very, VERY important NOT to go into any pet stores without disinfecting/changing clothes when you get home. You cannot handle rats at a pet store and then go home and handle your own, this is breaking quarantine.

Your rat breeding ventures have not gone well, likely because of poor quality and unhealthy animals and from poor quarantine methods.

Oh and if you're going to be keeping rats as pets, you need to have subQ fluids, a nebulizer, hospital cage/tank(5-10 gallon preferably or a no-level flat bottom cage), antibiotics such as Baytril, Doxycycline, Amoxicillin, as well as some steroids(injectable and inhalable). Pet rats are not cheap to keep.. I have 32 of them..