Can STDs be transmitted through saliva or through urine?

Yes, some can. For example, if a man has a GC/CT/trich urethritis, the germs are going to be delivered through the urethra by both urine and ejaculate. Hepatitis and herpes have been present in saliva as well. Chances of co-infection increase with breaks in oral or vaginal mucosa.
Yes. Yes all STDs be transmitted through saliva or through direct contact with urinary tract opening like urethra male and female.I am not sure how else you would be in contact with urine other than oral / genital or genital to genital contact. Condom use and monogamous relationships help alot to decrease std transmission.