There is no incubation period after the discovery of the first symptom of strep throat. This is because the incubation period of a disease ends the moment the first symptom of a disease is discovered, according to MedicineNet.com.
Thanks to the development of rapid strep tests, diagnosis of strep throat can be confirmed within five to 10 minutes of the test being administered, as WebMD explains. If a test is negative, a traditional culture test is often performed to rule out a false negative, and results are usually available after 48 hours. Strep throat continues to be contagious until after the first 24 hours of treatment with antibiotics is completed.