diagnosis of syphilis

diagnosis of syphilis & tests

 

Syphilis is difficult to diagnose clinically early in its presentation. Confirmation is either via blood tests or direct visual inspection using microscopy. Blood tests are more commonly used, as they are easier to perform. Diagnostic tests are, however, unable to distinguish between the stages of the disease.

How Do I Know If I Have Syphilis?

Blood tests are divided into nontreponemal and treponemal tests. Nontreponemal tests are used initially, and include venereal disease research laboratory (VDRL) and rapid plasma reagin tests. However, as these tests are occasionally false positives, confirmation is required with a treponemal test, such as treponemal pallidum particle agglutination (TPHA) or fluorescent treponemal antibody absorption test (FTA-Abs). False positives on the nontreponemal tests can occur with some viral infections such as varicella and measles, as well as with lymphoma, tuberculosis, malaria, endocarditis, connective tissue disease, and pregnancy. Treponemal antibody tests usually become positive two to five weeks after the initial infection. Neurosyphilis is diagnosed by finding high numbers of leukocytes (predominately lymphocytes) and high protein levels in the cerebrospinal fluid in the setting of a known syphilis infection.

 

Direct testing

Dark ground microscopy of serous fluid from a chancre

may be used to make an immediate diagnosis. However, hospitals do not always have equipment or experienced staff members, whereas testing must be done within 10 minutes of acquiring the sample. Sensitivity has been reported to be nearly 80%, thus can only be used to confirm a diagnosis but not rule one out. Two other tests can be carried out on a sample from the chancre: direct fluorescent antibody testing and nucleic acid amplification tests. Direct fluorescent testing uses antibodies tagged with fluorescein, which attach to specific syphilis proteins, while nucleic acid amplification uses techniques, such as the polymerase chain reaction, to detect the presence of specific syphilis genes. These tests are not as time-sensitive, as they do not require living bacteria to make the diagnosis.

References

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2. Karp, G; Schlaeffer, F; Jotkowitz, A; Riesenberg, K (January 2009). "Syphilis and HIV co-infection". European journal of internal medicine 20 (1): 9–13. doi:10.1016/j.ejim.2008.04.002. PMID 19237085.
3. Kent ME, Romanelli F (February 2008). "Reexamining syphilis: an update on epidemiology, clinical manifestations, and management". Annals of Pharmacotherapy 42 (2): 226–36. doi:10.1345/aph.1K086. PMID
4. Stamm LV (February 2010). "Global Challenge of Antibiotic-Resistant Treponema pallidum". Antimicrob. Agents Chemother. 54 (2): 583–9. doi:10.1128/AAC.01095-09. PMC 2812177. PMID 19805553.
5. White, RM (13 March 2000). "Unraveling the Tuskegee Study of Untreated Syphilis". Archives of Internal Medicine 160 (5): 585–98. doi:10.1001/archinte.160.5.585. PMID 10724044.
6. Committee on Infectious Diseases (2006). Larry K. Pickering, ed. Red book 2006 Report of the Committee on Infectious Diseases (27th ed.). Elk Grove Village, IL: American Academy of Pediatrics. pp. 631–44. ISBN 978-1-58110-207-9.
7. Eccleston, K; Collins, L; Higgins, SP (March 2008). "Primary syphilis". International journal of STD & AIDS 19 (3): 145–51. doi:10.1258/ijsa.2007.007258. PMID 18397550