Treat with revolution. You can get some at the vet or online at petsofoz petshed or joespetmeds. You'll need kitten formula and one tube treats like six rats. You only need three drops per rat on the nape of the neck.
Does not look like typical ringworm to me - which usually presents in a circular pattern of hair loss. Second picture almost looks like you can see little bugs. Either way, the treatment for any parasite (whether it be lice, fleas or mites) would be a dose of kitten strength revolution which you can obtain from your vet. If it is indeed mites you have to be extremely diligent about cleaning the environment and make sure (if you aren't already) to freeze any bedding before use as it is the most common way for mites to hitch a free ride without your knowledge. Good luck, this looks uncomfortable for the poor ratty.
I've found ringworm starts out looking fairly atypically in rats, and nearly always on the back. But, it's a good idea to treat with Revolution to rule out parasites, then do a fungal culture to see if it is ringworm. Ringworm's a huge pain so hopefully it's just parasites.