Clinical or Epidemiological Finding Laboratory Test Suspected LGV Figure 1 Fig 1A: LGV Case Definitions and Associated Laboratory Test (partially previously published in (2)) Case Definition Clinical or Epidemiological Finding Laboratory Test Suspected LGV Symptoms depending on disease stage; possibly supported by diagnostic procedures (e.g., anoscopy) a) Primary: genital ulcer, urethritis, proctitis b) Secondary: inguinal lymphadenopathy c) Tertiary: genital elephantiasis, lymph node scarring, fissures; or Sexual partner of probable or confirmed case No LGV-specific test Standard testing for STDs with similar or overlapping symptoms, in order to rule out or diagnose (e.g., HSV, Syphilis, Chlamydia, Chancroid, Donovanosis, Gonorrhea, Trichomonas) Probable LGV Clinical symptoms as above; or   Swab from affected site positive for CT by commercial NAAT (rectal, urethral, penile, vaginal) Laboratory-confirmed LGV Clinical symptoms as above, or Swab from affected anatomical site (previously CT NAAT+) positive for LGV by PCR Optional for epidemiologic investigation: L1, L2, or L3 genotype determination Fig. 1B. Laboratory Workflow for LGV outbreak investigation CT test (NAAT) at local laboratory LGV-PCR test Positive for CT Negative for CT Residual sample sent to CDC If sufficient material: Genotyping by PCR/Sequencing (L1, L2, L3) Negative Positive Patient management Outbreak investigation No LGV LGV probable LGV confirmed CT culture ensures sufficient biological material for genotyping Used if 1st swab unavailable Swab from mucosal anatomical site from suspected case Optional: 2nd swab stored Optional: 3rd swab for culture