The time taken for the clear expression of symptoms is known as the incubation period. The incubation period for the sexually transmitted diseases might vary depending on the causative organism. As soon as the person gets exposed to the microorganism, the symptoms do not show up. If a person tests for sexually transmitted diseases, the results of the test might be probably negative. The symptoms might take up to years for showing up in the patient. You should ask your doctor to guide you on this.