Parasites transmitted during sexual activity cause Trichomoniasis. The infection causes vaginal infections in women and urethral and prostate infections in men. For men or women, the initial portion of urine stream (first-catch urine sample). If the parasite can be seen under the microscope, no further tests are needed. If this test isn’t conclusive, tests called rapid antigen tests and nucleic acid amplification may be used.
This is a common sexually transmitted disease pre the CDC.