Syphilis Serology Michael Addidle

Immigration medical on a 35 yr old Tongan national who is pregnant and has history of rheumatoid arthritis. RPR +ve titre 1:16 TPPA +ve titre 1: 1280 A) Does this patient have syphilis?

Treponema pallidum Spirochaete 4 sub-species Pallidum-syphilis Endemicun- bejel Pertenue- yaws Carateum- pinta Impossible to differentiate serologically

Transmission of syphilis Sexual (including oro-genital and anogenital) Congenital Needlestick/blood transfusion

There was a young man from Back Bay Who thought syphilis just went away. He believed that a chancre Was only a canker That healed in a week and a day. But now he has "acne vulgaris“ -- (Or whatever they call it in Paris); On his skin it has spread From his feet to his head, And his friends want to know where his hair is. There's more to his terrible plight: His pupils won't close in the light His heart is cavorting, His wife is aborting, And he squints through his gun-barrel sight. Arthralgia cuts into his slumber His aorta's in need of a plumber But now he has tabes And saber-shinned babies While of gummas he has quite a number. He's been treated in every known way, But his spirochetes grow day by day; He's developed paresis Has long talks with Jesus, And thinks he's the Queen of the May

Background Early non-treponemal serological tests developed 1906 (Wassermann) Prevalence in big cities (Paris, New York) showed positive serology in 8-14% of the population. Treatment in the early 20th century usually involved either arsenic or mercury. Tuskegee study (1932-62)- trigger for establishing trial ethics

Ways to diagnose syphilis Serology Dark field microscopy PCR Clinical Treponemes cannot be cultured in vitro

Indications for testing. Screening attendees at antenatal clinics Screening attendees at SH clinics Screening donated blood samples Confirmation of positive screening tests Diagnostic testing in those with suggestive clinical features. Monitoring the therapeutic response

How can we test for Syphilis? Non-Specific Treponemal Tests VDRL (lecithins)/RPR(cardiolipin) Good for monitoring Rx Specific Treponemal Tests. FTA (“gold standard”, subjective) TPPA/TPHA (very sensitive) Immunoblot (Innolia) (good but still early days) Treponemal IgM/IgG EIA (good commercial automated screening test) Treponemal IgM (detected very early) Stay positive therefore useless for diagnosing re-infection or response to therapy.

How can we test for Syphilis? Traditionally screening was done with a non-treponemal test such as RPR or VDRL. Some smaller labs with low volumes still do this. Now vast majority of labs screen with a treponemal test and then confirm with a non-treponemal test. What problems might this lead to?

How can we test for Syphilis? A common result now is Treponemal IgM/IgG positive by EIA and a negative VDRL. What scenarios can give rise to this result? Extra work and management dilemnas for Sexual Health consultants.

Inno-Lia Immunoblot

Timing of testing After appearance of lesion suggestive of primary syphilis, only negative serology at three months will exclude syphilis. However the majority of patients have positive serology at time of symptoms. Some patients presenting with early chancre will have both negative treponemal and non-treponemal serological tests. Once infected, treponemal serological tests will remain positive for life except occasionally in very early treated syphilis.

Effect of Treatment on Testing VDRL and Treponemal specific IgM fall with treatment. However they may also become negative in chronic disease. Other Treponemal specific tests may decrease in titre but stay positive for the rest of the patients life. (except if disease treated really early)

Pitfalls Screening not recommended with a non-treponemal test alone ie VDRL due to the potential for false negatives (usually early disease or prozone effect). False positives: Can occur with both treponemal non specific tests and treponemal specific tests. If positive test results, repeat on same sample and on a repeat sample from the patient. HIV infection can play havoc with syphilis testing.

The old demented patient with positive syphilis serology Not that uncommon Look for documention of treatment for syphilis in the past. Seek advice from GUM specialist If VDRL positive need CSF Interpreting syphilis serology on CSF is complex. I go to textbooks/ask for peer assistance.

PCR and syphilis PCR- being used a little for diagnosis of early syphilis with reasonable sensitivity and good specificity. May be of most use in busy STI clinics where there are a reasonable number of patients presenting with chancres. Dark field microscopy of little use in oral and anal lesions. Not much use for secondary/tertiary/latent syphilis.

A new multiplex real-time PCR test for HSV1/2 and syphilis: an evaluation of its impact in the laboratory and clinical setting Abstract Objectives To develop, evaluate and implement a new multiplex real-time PCR test for the detection of herpes simplex virus (HSV)1, HSV2 and syphilis in a single sample using a single test. Methods A multiplex real-time PCR test detecting HSV1, HSV2 and Treponema pallidum was designed, validated and evaluated for a period of 6 months on patients attending the Sandyford Initiative (a series of genitourinary medicine clinics in and around Glasgow). A total of 692 samples were tested, and T pallidum PCR positives were confirmed by a second PCR at the Scottish Reference Laboratory (SBSTIRL). All PCR results were aligned with dark ground microscopy findings and serological results where available and compared. Results The laboratory validation of the multiplex assay showed the test to be sensitive, specific and robust. Of the 692 samples, 139 were positive for HSV1, 136 for HSV2, 15 for syphilis, one for both syphilis and HSV1, and 401 were negative; the reference laboratory confirmed all T pallidum PCR-positive samples. The PCR test was more sensitive than both dark ground microscopy and serological testing for the diagnosis of primary syphilis. Conclusions The introduction of this new test has led to a better turnaround time for the diagnosis of genital ulcer disease, better detection of primary syphilis infection, and the detection of unexpected cases of syphilis where the aetiological agent suspected was HSV.

Follow-up Immigration medical on a 35 yr old Tongan national who is pregnant and has history of rheumatoid arthritis. Treated for syphilis. 2 years post treatment, re-tested. Results are now: RPR +ve titre 1:4 TPPA +ve titre 1: 1280 What are the possible scenarios?

Take Home Messages Be aware of different serological tests for syphilis and the difference between treponemal and non-treponemal tests. Note that screening low prevalence populations increases chances of false positives.