The spirillary form causes relapsing fever, rash, and regional lymphadenitis. The condition is diagnosed by detecting the bacteria in skin, blood, joint fluid, or lymph nodes. The symptoms generally appear two weeks after infection for spirillary RBF. Treatment of rat bite fever involves administration of amoxicillin 1 g per oral, procaine penicillin G 600,000 units IM every 12 hours, or penicillin V 500 milligrams per oral for 7 to 10 days. Erythromycin 500 milligrams might be administered to people who are allergic to penicillin.