Rigellian Kassaba fever was a disease utilized as part of a ruse by Doctor Leonard McCoy in 2268.

He thus explained the feigned symptoms of Spock in order to help gain control of the USS Enterprise from the invading Kelvans. According to McCoy, patients who suffered from this disease could experience occasional re-occurrences as many as ten years after their initial infection, but it was treatable provided one received the proper dosage of stokaline in time. (TOS: "By Any Other Name")