Short answer: Yes, you can get scabies from an infected toilet seat! Scabies is highly contagious and if the person that used the toilet before you had a bad case of it, they might be lingering on the seat itself, just waiting for you to park your butt down. This is the main reason why you'll want to do your best to disinfect public toilets before you use them, and why you should keep your bathroom clean at home. While scabies is not common enough to walk around being paranoid all the time, you'll want to be aware that it does exist and just stay cautious.
If you are experiencing intense itching, you may have contracted a case of the scabies. They are also referred to as the seven year itch. It will develop into a rash and cause an infection if left untreated. The scabies mite itself gets under your skin and burrows it's way along, all the while cause an severe itching sensation.
You can get scabies anywhere on the body, but their favorite places are in cracks and crevices. Look for them in places like between your toes and fingers, around your waist, in the genital region, the underarms, and for women under the breasts. If you scratch too much you might get a secondary infection like strep or impetigo.
If you are older, or malnourished, or if you have a poor immune system you might get a worse case of scabies, where they can crust over and get really bad. You definitely don't want to get Norwegian scabies. Do a Google image search for it if you want to be grossed out.
Since there is no vaccine for scabies you just have to use precaution and hope you don't get it. If you do, your doctor can provide medications that will help calm the itch and kill the scabies mites. Prevention is the best cure, so you should thoroughly clean your home to prevent its spread. Here are some things you can do to make sure you don't get it, or if you already did get it, to not get it again:
Be sure to treat all furniture and bedding. This makes a lot of sense because it's where we spend the most time, and provides a nice warm place for scabies bugs to linger. Also you'll want to vacuum up all floors, carpeting, and any rugs you might have. Use disinfectant like Lysol in the bathroom with a mop on the floor and other smooth surfaces. Be sure to scrub down the shower and tub each time you use it. And lastly, every day you'll want to wash the clothes you've worn that day using hot water, and drying them on the hot setting and them using a steam iron on them.
Show no mercy when it comes to scabies!