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1.  Enzyme-linked immunosorbent assay for detection of antibodies to the venereal disease research laboratory (VDRL) antigen in syphilis. 
Journal of Clinical Microbiology  1987;25(9):1711-1716.
An enzyme-linked immunosorbent assay (ELISA) for detection of immunoglobulin G (IgG) and IgM to cardiolipin, lecithin, and cholesterol (VDRL [Venereal Disease Research Laboratory] ELISA) is described. The specificity of the VDRL ELISA for IgG and IgM was 99.6 and 99.5%, respectively, with sera from 1,008 persons without syphilis. For a group of patients with false-positive results in traditional nontreponemal tests and for patients with autoimmune diseases, the VDRL ELISA for IgG had a higher specificity than the VDRL ELISA for IgM. The sensitivity for IgG and IgM with 118 sera from patients with untreated syphilis was 96.6 and 94.9%, respectively, which was equivalent to the sensitivities of the traditional nontreponemal tests. The performance of the VDRL ELISA was compared with that of an ELISA that uses cardiolipin as the antigen (cardiolipin ELISA). The VDRL ELISA was significantly more sensitive (P less than or equal to 0.01) than the cardiolipin ELISA with 25 sera from syphilis patients but was less sensitive (P less than or equal to 0.01) with 53 sera from patients with autoimmune diseases. The antibody reactivity in the VDRL ELISA could not be absorbed out by lecithin and cholesterol, and the sera from patients with syphilis did not react in an ELISA that uses cholesterol and lecithin as the antigen. This indicates that cholesterol and lecithin, although not antigenic by themselves, may change the structural form of the epitope on cardiolipin so that it becomes more recognizable for antibodies in syphilis and less recognizable for antibodies in autoimmune diseases. The results of the VDRL ELISA were expressed in percentages of the absorbance value of a positive control. The VDRL ELISA gave, without titration of sera, quantitative results that correlated with the quantitative results of the traditional nontreponemal tests obtained by titration. The VDRL ELISA will be well suited for large-scale testing for syphilis and may replace other nontreponemal tests.
PMCID: PMC269313  PMID: 3308951
2.  Syphilis serology and HIV infection in Harare, Zimbabwe 
Sexually Transmitted Infections  1999;75(6):426-430.
OBJECTIVE: To determine the reliability of serological tests in detecting syphilis in a factory worker cohort and examine the impact of concurrent HIV infection on serological tests for syphilis. METHOD: Reactions to non-treponemal and treponemal antigens were tested using sera from a cohort of 3401 factory workers in Harare, Zimbabwe. The participants consented to regular testing for syphilis, by VDRL, and HIV using two ELISAs. All sera from men who were VDRL positive, and a random sample of VDRL negative sera, were tested by RPR, TPHA, and where appropriate FTA-Abs. From the results, men were defined as having no syphilis, active syphilis, incident syphilis, historic syphilis, or giving biological false positive reactions. RESULTS: 709 sera were examined from 580 men. There were 78 cases of active syphilis in the cohort, giving a prevalence of 2.3%, and the seroincidence was 0.25 per 100 person years of follow up. The prevalence of HIV in the cohort was 19.8%. There was a strong association between syphilis, whether active, incident or historic, and HIV seropositivity. With both HIV positive and negative sera the negative predictive values of VDRL and RPR were > 99.9% while the positive predictive value for VDRL (30%) was lower than for RPR (39%). Biological false positive reactions were detected in 0.5% of the cohort, with in most cases a transient rise in VDRL titres up to < 1/16. Higher false positive titres occurred in five men, each of whom was HIV positive. CONCLUSIONS: The VDRL is reliable in detecting possible cases of syphilis even in a community with a high prevalence of heterosexually transmitted HIV. There is need, however, for confirmatory tests. The prevalence of syphilis in this cohort is very low in comparison with other countries in southern Africa, but is consistent with recent data from Harare. Despite a strong association between syphilis and HIV it was clear that syphilis could not be counted as a major factor fueling the HIV epidemic in Zimbabwe. 

PMCID: PMC1758263  PMID: 10754951
3.  Visuwell Reagin, a non-treponemal enzyme-linked immunosorbent assay for the serodiagnosis of syphilis. 
Journal of Clinical Microbiology  1989;27(10):2300-2304.
A urease-based enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of reagin antibodies in serum. Visuwell Reagin (ADI Diagnostics Inc., Rexdale, Ontario, Canada) is a non-treponemal screening test for the serodiagnosis of syphilis which has the benefits of large batch testing, automatability, and objective interpretation of results. Unheated, undiluted sera are incubated in 96-well microtiter plates coated with a modified cardiolipin-lecithin-cholesterol antigen. Antibody bound to the plate is detected by an anti-human immunoglobulin G-urease conjugate. The procedure consists of three steps, with a total test time of 60 min. Visuwell Reagin ELISA was compared with the Venereal Disease Research Laboratory (VDRL) test and the reagin screening test (RST) with the following results. For ELISA versus the VDRL test, the sensitivities for untreated syphilis (n = 37) were 97.3% for both ELISA and the VDRL test, the confirmatory positive values (n = 79) were 84.8% for ELISA and 72.2% for the VDRL test, and the specificities for normal samples (n = 1,327) were 98.8% for ELISA and 99.5% for the VDRL test. For ELISA versus RST, the sensitivities for untreated syphilis (n = 57) were 94.7% for ELISA and 87.7% for RST, the confirmatory positive values (n = 26) were 96.2% for ELISA and 92.3% for RST, and the specificities for normal samples (n = 1,891) were 99.6% for ELISA and 99.3% for RST. The overall concordance values of ELISA with VDRL test and RST were 96.7 and 97.9%, respectively. The specificity of ELISA compared with that of RST may be underestimated, since confirmatory data were not available for all apparent false-positive samples. Visuwell Reagin had increased sensitivity and similar specificity compared with flocculation tests.
PMCID: PMC267013  PMID: 2584380
4.  Use of Synthetic Cardiolipin and Lecithin in the Antigen Used by the Venereal Disease Research Laboratory Test for Serodiagnosis of Syphilis 
The Venereal Disease Research Laboratory (VDRL) test is a microflocculation test for syphilis that uses an antigen containing cardiolipin, lecithin, and cholesterol. For more than 50 years, the preparation of natural cardiolipin and lecithin for this test has been based on the Pangborn method which involves isolating and purifying these components from beef hearts. This process is tedious and time-consuming and results in a variable purity range. In our studies, we found that a VDRL antigen using synthetic tetramyristoyl cardiolipin and synthetic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (lecithin) was as specific in detecting syphilis as a VDRL antigen made with natural components. In 85% of the cases, we obtained an endpoint titer of 1/2 or 1 dilution more than a titer obtained with a VDRL antigen made with natural components. The use of these pure synthetic compounds, with a purity of 99%, would offer advantages in the standardization and stability of the VDRL antigen. Because this antigen is the basic ingredient in the preparation of nontreponemal reagents such as the rapid plasma reagin, toluidine red unheated serum test, and the unheated serum reagin, the use of this synthetic VDRL antigen should also increase the reactivity of these reagents.
PMCID: PMC95930  PMID: 10882668
5.  Seroreversion of the serological tests for syphilis in the newborns born to treated syphilitic mothers. 
Genitourinary Medicine  1995;71(2):68-70.
BACKGROUND--IgG antibodies from mothers adequately treated for syphilis can cross the placenta and appear in the sera of healthy newborns without infection. In such infants, a false diagnosis of congenital syphilis is often made. We have designed a retrospective survey to determine the time of seroreversion of the serological tests for syphilis (STS) in uninfected newborns born to mothers who were adequately treated for syphilis. MATERIALS AND METHODS--Fifty two seropositive, untreated newborns born to 51 mothers treated for syphilis were studied. The newborns were followed at 1, 3, 6, 9, and 12 months of age until seroreversion was detected. The VDRL test was followed until 12 months in 12 of the 22 newborns who were positive at birth, the TPHA in 21 of the 46 newborns, and the FTA-ABS test in 22 of the 48 newborns. RESULTS--In the first serological tests done within 1 month after birth, the VDRL was positive in 22 newborns (42%), the TPHA in 46 (88%), and FTA-ABS in 48 (92%). The VDRL seroreverted within 6 months after birth in 84%, and within 1 year in 100%. The TPHA test seroreverted in 95% within 1 year after birth. The FTA-ABS test seroreverted in 100% within 1 year after birth. CONCLUSIONS--In most seropositive, untreated newborns born to treated mothers the VDRL became negative within 6 months after birth and the TPHA and FTA-ABS within 1 year. This result is consistent with current Centers for Disease Control (CDC) guidelines. However, although the CDC guidelines are adequate in general, we think that some revision is desirable concerning the IgM test and combination of the test results in order to rule out congenital syphilis in seropositive, nonsymptomatic newborns born to the treated mothers.
PMCID: PMC1195455  PMID: 7744415
6.  Evaluation of the usefulness of Treponema pallidum hemagglutination test in the diagnosis of syphilis in weak reactive Venereal Disease Research Laboratory sera 
Background and Objectives:
Biological false positive (BFP) reactivity by the Venereal Disease Research Laboratory (VDRL) test used for diagnosis of syphilis is a cause for concern. The use of the VDRL as a screening procedure is challenged by some studies. The aim of this study is to determine the prevalence of BFP reactions in different subject groups and to assess the usefulness of Treponema pallidum hemagglutination (TPHA) test in low titre VDRL reactive sera.
Materials and Methods:
A total of 5785 sera from sexually transmitted diseases (STD) clinic attendees, antenatal clinic attendees, husbands of antenatal cases, peripheral health centres attendees (representing community population) and from patients referred from different OPDs/wards were screened for BFP reactions by the VDRL test. Sera reactive in the VDRL test were confirmed by the TPHA test.
Out of 80 qualitative VDRL reactive sera, 68 had <1:8 titre on quantitation and TPHA was positive in 59 samples, indicating BFP reactivity in 0.2% in all the subject groups. BFP was nil in the community population. The male-to-female ratio of BFP reactions was 2:1. VDRL and TPHA positivity was highest (76%) in the age group of 20-29 years. The seroprevalence of syphilis varied from 0.4% to 3.5% in different patient groups.
The results of this study highlight that the TPHA positivity was high (86.8%) in sera with VDRL titre less than 1:8. Therefore, for the diagnosis of syphilis, it is recommended that a confirmatory test such as TPHA should be performed on all sera with a reactive VDRL regardless of its titre.
PMCID: PMC3505284  PMID: 23188934
Biological false positive; Syphilis; Treponema pallidum hemagglutination; Venereal disease research laboratory
7.  Comparing the performance characteristics of CSF-TRUST and CSF-VDRL for syphilis: a cross-sectional study 
BMJ Open  2013;3(2):e002204.
In this study, we aimed to determine the performance characteristics of toluidine red unheated serum test on cerebrospinal fluids (CSF-TRUST) as compared to venereal disease research laboratory test on cerebrospinal fluids (CSF-VDRL) for laboratory the diagnosis of neurosyphilis.
A cross-sectional study.
Sexually transmitted infections (STIs) clinics.
Participants and methods
CSF and serum samples were collected from 824 individual STD clinic patients who have syphilis and are suspected to progress to neurosyphilis within a 9-month period. CSF-VDRL and CSF-TRUST were performed parallelly on the same day when collected. Treponema pallidum particle agglutination (TPPA) tests were also performed on the CSF and the serum samples, and biochemical analysis of the CSF samples was also performed.
The overall agreement between CSF-TRUST and CSF-VDRL was 97.3%. The reactive ratios of the CSF samples were 22.1% by CSF-TRUST and 24.8% by CSF-VDRL, respectively. All CSF-TRUST-reactive cases were reactive in the CSF-VDRL. Twenty-two samples with CSF-TRUST-negative were tested CSF-VDRL-reactive with low titres (1 : 1 to 1 : 4). Over 97% of the double-reactive CSF samples (CSF-VDRL and CSF-TRUST) had an identical titre or a titre within a two-fold difference. The agreement of CSF-TPPA and CSF-VDRL was 71.9%. Similarly, the agreement of CSF-TPPA and CSF-TRUST was 69.2%.
Our results revealed that CSF-TRUST could be used as an option for CSF examination in settings without CSF-VDRL in place.
PMCID: PMC3586078  PMID: 23430600
Syphilis; Laboratory Methods; China
8.  Serological tests for syphilis in Saudi Arabia. 
Genitourinary Medicine  1986;62(5):293-297.
A total of 6684 sera were initially screened for syphilis by the Venereal Disease Research Laboratory (VDRL) test and the Treponema pallidum haemagglutination assay (TPHA). Reactive sera from either or both these tests were tested for confirmation by the fluorescent treponemal antibody-absorbed (FTA-ABS) test. VDRL biological false positive reactors were detected in 0.5% of the total sera examined, with 0.4% and 0.8%, respectively, obtained in pregnant women and blood donors. Eight sera (0.1%) were found to be positive in the TPHA test alone. An overall positivity of 2.7% for syphilis was detected, with a 0.85% positivity in antenatal patients. Infection with T pallidum seemed to be more common in men than in women (1.6:1) and predominated in the age group 20-39 years. Serological testing of sera from 26 mother and infant pairs allowed one case of congenital syphilis to be detected by FTA-ABS (IgM) and identified VDRL biological false positivity in seven infants.
PMCID: PMC1011979  PMID: 3770753
9.  An IgM capture enzyme linked immunosorbent assay to detect IgM antibodies to treponemes in patients with syphilis. 
Genitourinary Medicine  1989;65(2):79-83.
A new IgM capture enzyme linked immunosorbent assay (ELISA) was compared with the 19S(IgM) fluorescent treponemal antibody absorption (19S(IgM)FTA-ABS) test for detecting IgM antibodies to treponemes. Serum samples from 180 people, 109 with various stages of untreated syphilis, 45 with treated syphilis, and 26 non-infected, were investigated. In all diagnostic groups of syphilis the reactivity of the IgM capture ELISA was similar to that of the 19S(IgM)FTA-ABS test except in untreated neurosyphilis, for which the IgM capture ELISA was significantly less sensitive. The IgM capture ELISA was very sensitive in congenital (100%, 5/5) and primary (82%, 18/22) syphilis, but less sensitive in secondary (60%, 12/20), latent (53%, 16/30), neurosyphilis (34%, 11/32), and treated (11%, 5/45) syphilis. False positive IgM capture ELISA results were not found in five people who gave false positive Venereal Disease Research Laboratory (VDRL) reactions or in 21 neonates born to mothers adequately treated for syphilis before or during pregnancy. This indicated that the IgM capture ELISA was very specific. The course of antitreponemal IgM reactivity after treatment of early infectious syphilis was followed up in six patients. The quantity of IgM antibody declined in nearly all patients after treatment, but still remained detectable in five patients up to six months after treatment. In contrast, non-treponemal antibodies measured by the VDRL test disappeared in four out of six patients within five months from starting treatment. In conclusion, the IgM capture ELISA may be useful for easy and sensitive detection of IgM antibodies to treponemes in patients with congenital and primary syphilis. A positive test result in these cases indicates that patients should receive treatment if they have not been treated recently. The test is not, however, recommended to replace the VDRL test to monitor patients treated for syphilis.
PMCID: PMC1194291  PMID: 2666303
10.  Recent observations on the serology of syphilis. 
Routine screening of 404 742 sera by the automated micro-haemagglutination assay (AMHA-TP) and the Venereal Disease Research Laboratory (VDRL) test showed that 9848 specimens gave a reactive result to one of the three assays. Reactive results were confirmed by the fluorescent treponemal antibody absorption (FTA-ABS) test. The possibility of false-positive results varied from 0.04-0.38% of all specimens or from 1.7-15.7% of reactive sera. The VDRL test failed to detect reactivity in 56.54% of sera from patients who had previously been infected with Treponema pallidum. The importance of routine testing by the AMHA-TP is illustrated by the detection of four patients with mesaortitis and two with active neurosyphilis among a selected group of 54 patients who had non-reactive results to the VDRL test. Testing of cerebrospinal fluid specimens by the AMHA-TP test produced more specific results than by the other two tests.
PMCID: PMC1045718  PMID: 6989443
11.  Prevalence of Hepatitis B, C, HIV and syphilis markers among refugees in Bari, Italy 
BMC Infectious Diseases  2010;10:213.
The aim of this study was to assess the prevalence of Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV) serological markers and the prevalence of VDRL positive subjects in a population of refugees of various nationalities, living in the Asylum Seeker Centre in Bari Palese, Southern Italy.
The study was carried out in the period May-July 2008 and recruited only voluntarily enrolled healthy refugees. HBsAg, anti-HBc, anti-HCV and anti-HIV virus antibodies were detected. VDRL syphilis screening was also carried out on the serum samples.
A total of 529 refugees, 442 males and 87 females, aged between 7 and 52 years, were studied. Of these, 510 were from Africa and 19 from Asia.
Forty-four individuals (8.3%) were HBsAg positive and 241 (45.6%) were anti-HBc positive. A total of 24 (4.5%) individuals were anti-HCV positive. Eight asylum seekers (1.5%) were HIV positive. VDRL tests were performed on 269 subjects and 4 (1.5%) were positive. 12.3% of the study population had serological markers of chronic and transmissible infections with potential blood-borne or sexual transmission.
In Italy, a suitable protocol is necessary for the early diagnosis of infectious diseases on entering Asylum Centres, so allowing the adoption of prevention measures to safeguard the health of the individuals, the residents and workers in the Centres and the general population.
PMCID: PMC2916911  PMID: 20646306
12.  The association of syphilis with cirrhosis: the role of alcohol and serum hepatitis 
Postgraduate Medical Journal  1975;51(592):69-73.
The role of syphilis and alcohol was investigated in a prospective study of patients with cirrhosis of liver in Uganda, and results were correlated with the histological type of cirrhosis, and serological tests for hepatitis B antigen (HB Ag). Eighteen out of eighty (22·5%) patients with histologically-proven cirrhosis had positive serology for syphilis (VDRL and TPI). A high incidence of alcoholism (80%) and syphilis (60%) was found in patients with micronodular cirrhosis who were all negative for HB Ag. By contrast, HB Ag was detected in 37% of patients with macronodular cirrhosis who had a much smaller incidence of syphilis and alcoholism. Although chronic infection with hepatitis B virus related to HB Ag appears to be an important factor in the pathogenesis of cirrhosis in at least 30% of cases, infection acquired during past treatment for syphilis is not an important cause of the association of syphilis with cirrhosis in this population. Subdivision of patients with cirrhosis into those with and those without a history of severe alcohol abuse showed that the difference between the incidence of syphilis in the two groups is significant statistically. However, evidence of syphilis in association with non-alcoholic as well as alcoholic cirrhosis in this and other previously reported series suggests that the association between the two diseases cannot be entirely explained through the common factor of alcoholism, and other factors may also be responsible.
PMCID: PMC2495710  PMID: 1114150
13.  Comparison of the Cerebrospinal Fluid (CSF) Toluidine Red Unheated Serum Test and the CSF Rapid Plasma Reagin Test with the CSF Venereal Disease Research Laboratory Test for Diagnosis of Neurosyphilis among HIV-Negative Syphilis Patients in China 
Journal of Clinical Microbiology  2014;52(3):736-740.
In this study, we aimed to investigate the performance of nontreponemal antibody tests in cerebrospinal fluid (CSF) specimens from syphilis patients. From September 2009 to September 2012, CSF specimens were collected at the Shanghai Skin Disease Hospital in Shanghai, China, from 1,132 syphilis patients without HIV infection, including 154 with symptomatic and 56 with asymptomatic neurosyphilis. All of the CSF specimens underwent testing with a rapid plasma reagin (RPR) test, an RPR-V (commercial RPR antigen diluted 1:2 in 10% saline) test, the toluidine red unheated serum test (TRUST), and the Venereal Disease Research Laboratory (VDRL) test. Specificities, sensitivities, positive predictive values (PPVs), negative predictive values (NPVs), and kappa values were calculated to determine the performances of the tests. We compared results of the CSF-VDRL, CSF-RPR, CSF-RPR-V, and CSF-TRUST among patients with symptomatic and asymptomatic neurosyphilis who had reactive CSF-Treponema pallidum particle agglutination (TPPA) test results. Overall, the CSF-VDRL test was reactive in 261 patients (23.1%). There were no cases in which the CSF-VDRL was nonreactive and CSF-RPR, CSF-RPR-V, or CSF-TRUST was reactive. Agreement between the results of CSF-TRUST and CSF-RPR was almost perfect (κ = 0.861), with substantial agreement between the results of CSF-RPR and CSF-RPR-V (κ = 0.740). The sensitivities of CSF-VDRL, CSF-RPR, CSF-RPR-V, and CSF-TRUST were 81.4%, 76.2%, 79.5%, and 76.2%, respectively. Compared to CSF-VDRL, CSF-RPR, CSF-RPR-V, and CSF-TRUST had comparable PPVs and NPVs. However, the specificity of CSF-VDRL (90.3%) was significantly lower than those of the other tests (92.7 to 93.4%). Therefore, CSF-RPR, CSF-RPR-V, and CSF-TRUST can be considered alternative tests for neurosyphilis diagnosis in HIV-negative populations, particularly when the CSF-VDRL is not available.
PMCID: PMC3957747  PMID: 24335955
14.  Evaluation of automated large-scale screening tests for syphilis. 
Journal of Clinical Pathology  1976;29(4):317-321.
Two methods of performing serological screening tests for syphilis are compared. One consisted of the Venereal Diseases Reference Laboratory (VDRL) slide test, the cardiolipin Wassermann reaction (CWR), and the Reiter protein complement fixation test (RPCFT) performed manually; the other was a fully automated system using two Technicon AutoAnalyzers (AAII), one for the automated reagin test (ART) and the other for automated complement fixation tests. The absorbed fluorescent treponemal antibody test (FTA-ABS) was used as a final arbiter in all cases found to be seropositive by either method. A pooled antigen consisting of a mixture of cardiolipin and Reiter protein was used for the automated complement fixation test, thus increasing the scope and capacity of the system. The AutoAnalyzer was shown to be capable of performing 400 cardiolipin and Reiter complement fixation tests and 700 automated reagin tests in an 8-hour day. Modification of the complement fixation test method to take advantage of the highly sensitive colorimeter resulted in a significant increase in sensitivity and a corresponding saving in reagents. Of the 7843 sera tested, 258 gave a positive result in one or more of the screening tests. The automated test detected many more Reiter positive sera (127) than the manual test (83). Conversely, fewer CWR positive sera were detected by the automated test (60) than by the manual test (82). There was little difference between the number of positive sera detected by the ART (73) and the VDRL slide test (71). In 19 instances the automated tests detected positive sera which registered as completely negative in the manual tests, and four seropositive cases which the automated tests had failed to detect were detected by the manual tests, and four seropositive cases which the automated tests had failed to detect were detected by the manual tests. It was concluded that a combination of the ART and automated Reiter protein complement fixation test (ARPCFT) would be ideal for use in a large-scale screening programme for the detection of syphilis.
PMCID: PMC476055  PMID: 777045
15.  VDRL titres in early syphilis before and after treatment. 
Genitourinary Medicine  1992;68(2):120-122.
OBJECTIVE--To observe the pretreatment VDRL titres in different stages of early syphilis and evaluate the changes in VDRL titre following treatment using different treatment schedules. DESIGN--Retrospective study was carried out by analysing the records of cases of early syphilis treated between 1976 to 1981. SETTING--Armed Forces personnel treated at different service hospitals in India. SUBJECTS--Of 3183 cases of early syphilis treated with different regimens during this period, 1532 were fully followed-up for a period of 30 months. Records of these 1532 cases were analysed. MAIN OUTCOME MEASURES--Assessment of VDRL titres before treatment and during post treatment surveillance period of 30 months. Attainment of non-reactivity of VDRL test in various stages of early syphilis using different treatment schedules was evaluated. RESULTS--Relatively higher titres were observed in secondary syphilis. Following treatment it was observed that VDRL test was still reactive at the end of 6 months in 16.47% of primary, 27.56% of secondary and 18.95% of early latent cases; at the end of 12 months in 11.38% of primary, 17.25% of secondary and 15.79% of early latent cases while at 30 months reactivity was still observed in 6.60% of primary, 8.39% of secondary and 11.58% of early latent cases. CSF was examined in 1173 cases at 6 months, of which one case revealed VDRL reactivity while two cases showed reactivity amongst 1188 CSF examined at 30 months. There has been no significant difference with broad spectrum antibiotics and 2.4 MU benzathine penicillin. Results were better with 4.8 MU benzathine penicillin and procaine penicillin. CONCLUSION--VDRL test appears to be a reliable test for the follow-up of treated patients in early syphilis. Early treatment prevents development of seropositivity in seronegative syphilis while majority of seropositive cases attain seronegativity by 6 months. Higher doses of benzathine penicillin and procaine penicillin accelerate the speed of seroconversion.
PMCID: PMC1194824  PMID: 1582655
16.  Screening for Syphilis in an Aged Psychiatrically Impaired Population 
Western Journal of Medicine  1976;125(5):361-363.
A serum Venereal Disease Research Laboratories (VDRL) test was carried out in 216 elderly patients with dementia or “functional” psychiatric illness, or both, as part of a community based screening program. The VDRL test was positive in 13 patients, 11 of whom (5.1 percent) had an actual past or present syphilitic infection as confirmed by the fluorescent treponemal antibody absorption test (FTA-Abs). In six patients (2.8 percent) syphilis was newly detected, and in another two patients previously detected syphilis had been inadequately treated. Only two (0.9 percent) biologic false positive reactors were detected. These results question the belief that aging per se is a common cause of the biologic false positive reaction; and indicate a relatively high incidence of past or present syphilitic infection in geriatric patients with psychiatric illness in the community who have been referred for crisis intervention.
PMCID: PMC1237348  PMID: 983014
17.  Enzyme linked immunosorbent assays with Treponema pallidum or axial filament of T phagedenis biotype Reiter as antigen: evaluation as screening tests for syphilis. 
Genitourinary Medicine  1986;62(6):367-372.
Enzyme linked immunosorbent assays with an ultrasonicate of Treponema pallidum (TP-ELISA) or axial filament of Treponema phagedenis biotype Reiter (AF-ELISA) were developed to detect treponemal antibody. TP-ELISA and AF-ELISA were compared with the T pallidum haemagglutination assay (TPHA), the fluorescent treponemal antibody-absorbed (FTA-ABS) test, and the Venereal Disease Research Laboratory (VDRL) test for sensitivity and specificity of serodiagnosis of syphilis. A total of 1423 serum samples, 253 from patients with various stages of syphilis, 500 from patients attending a sexually transmitted disease (STD) clinic, and 670 from people without syphilis, were investigated. At all stages of syphilis the sensitivity of the TP-ELISA, the AF-ELISA, the TPHA, and the FTA-ABS test did not differ significantly, except that the AF-ELISA was less sensitive than the TPHA (p less than 0.05) for treated syphilis. In primary syphilis, neurosyphilis, and treated syphilis the TP-ELISA and AF-ELISA were significantly more sensitive than the VDRL test (p less than 0.05). The specificity of all tests was comparable (p greater than 0.05). The TP-ELISA and AF-ELISA appear to be good alternatives to the TPHA as screening tests for syphilis. Because of the easy availability of a well defined antigen the AF-ELISA seems to be better suited for large scale testing.
PMCID: PMC1012000  PMID: 3546079
18.  Italian National Survey of Blood Donors: External Quality Assessment (EQA) of Syphilis Testing▿  
Journal of Clinical Microbiology  2009;48(3):753-757.
The detection of syphilis among blood donors may reveal high-risk sexual behavior, which can go unreported at the time of donor selection and compromise the safety of the donated blood. In Italy, blood is collected, tested, and distributed by transfusion services (TSs), which also perform outpatient transfusions. Although the TSs must screen for syphilis by law, there are no indications of the specific type of method to be used, generating discrepancies in the results obtained by the different TSs. To determine the proficiency of the TSs in screening for syphilis, we performed an external quality assessment (EQA). The EQA was based on two shipments of serum panels; 133 and 118 of the 326 existing TSs participated in the first and second shipments, respectively. Each panel consisted of both positive and negative serum samples. The results confirmed that the use of a single nontreponemal test (the Venereal Disease Research Laboratory [VDRL] and the rapid plasma reagin [RPR] tests) is the least sensitive means of identifying samples that are positive for syphilis antibodies. We also found that the interpretation of the results of manual techniques, such as the RPR test, the VDRL test, the Treponema pallidum hemagglutination (TPHA) assay, and the T. pallidum particle agglutination (TPPA) assay, can vary greatly among different TSs and operators. Total Ig enzyme immunoassays (EIAs) are the most sensitive. However, the determination of syphilis on the basis of the results of a single test is not sufficient for an accurate screening; and all blood units should thus be assessed by two distinct treponemal tests, that is, a total Ig EIA and the TPHA or the TPPA assay.
PMCID: PMC2832432  PMID: 20042617
19.  Interpreting Serological Tests for Syphilis 
Canadian Family Physician  1987;33:1829-1832.
Serological tests can be helpful in diagnosing syphilis. The ideal test would be highly specific in all stages of the disease; it would be 100% sensitive and would revert to negative with treatment, thereby allowing the physician to monitor treatment effect. No single test satisfies these requirements. Being alert to the signs and symptoms of syphilis in all its stages and familiar with the meaning of the common serological tests (VDRL, MHA-TP, FTA-ABS) will help physicians to detect early treatable disease and thus prevent tertiary syphilis or spread to others. This article describes the serological tests used to diagnose syphilis and outlines what to look for if a VDRL is reported as reactive.
PMCID: PMC2218216  PMID: 21263802
syphilis; serology; sexually transmitted diseases
20.  Comparison of a new rapid plasma reagin card test with the standard rapid plasma reagin 18-mm circle card test and the venereal disease research laboratory slide test for serodiagnosis of syphilis. 
Journal of Clinical Microbiology  1983;17(2):249-254.
The rapid plasma reagin (RPR) card test manufactured by Beckman Instruments, Inc., was compared, qualitatively and quantitatively, with the Venereal Disease Research Laboratory (VDRL) slide test and the standard RPR 18-mm circle card tests for the serodiagnosis of syphilis. Sera from 638 individuals were used in this study. Two pilot lots and two production lots of antigen were submitted by Beckman Instruments, Inc., for evaluation. Qualitative agreement among the three RPR card tests was 98.1%; between the Beckman RPR card and the VDRL slide tests, 95.0%; and between the reference RPR card and the VDRL slide tests, 95.5%. The Beckman RPR card test was 95.3% specific, whereas the specificities of the reference RPR card and the VDRL slide tests were 98.8% and 96.1%, respectively. Sensitivities of the three nontreponemal tests were: Beckman RPR card test production lots, 94.7%; reference RPR card test, 96.8%; and VDRL slide test, 90.6%. Quantitative agreement +/- 1 dilution among the three RPR card tests was 93.0%, whereas quantitative agreement was approximately 40% when both RPR card tests were compared with the VDRL slide test. We found the Beckman RPR card test comparable to the standard RPR card tests. Therefore, the decision of which test to use for the serodiagnosis of syphilis is at the discretion of the user.
PMCID: PMC272616  PMID: 6833479
21.  Rising trends of syphilis in a tertiary care center in North India 
Background and Objectives:
Syphilis is a classical sexually transmitted disease (STD), caused by Treponema pallidum subsp. pallidum. In this retrospective study, we analyzed trends of syphilis prevalence in patient groups attending our tertiary care center.
Materials and Methods:
The data was obtained by reviewing laboratory records of the STD laboratory from January 1, 2006 to December 31, 2011. Cases positive by both Venereal Disease Research Laboratory (VDRL) and Treponema pallidum particle agglutination (TPPA) tests were analyzed for seroprevalence of syphilis in different groups, and to analyze the rising or falling trends, if any.
A total of 28,920 serum samples were received in the 6-year study period for VDRL testing, of which 972 (3.4%) were found to be reactive. Of these, 1722 sera were also submitted for TPPA testing, 374 (21.7%) of which were positive. A total of 375 samples were submitted for both tests, indicating biological false positivity of 0.27%. A rising trend, though not statistically significant, was observed in pregnant women, drug users and patients from wards/out-patient departments, while a statistically significant rise in prevalence of syphilis was found in HIV-positive individuals. A falling trend (not statistically significant) was observed in STD clinic attendees.
An increasing trend of syphilis was observed during the study period when all groups were analyzed together, especially in HIV-seropositive individuals, which calls for continued and sustained efforts for case detection, treatment, and preventive measures to contain the disease.
PMCID: PMC4660552  PMID: 26692604
Epidemiology; India; seroprevalence; syphilis; trends
22.  Biological false positive serological tests for syphilis in the Jamaican population. 
Genitourinary Medicine  1990;66(2):76-78.
A total of 19,067 sera were screened for biological false positive (BFP) reactivity by the Venereal Disease Research Laboratory (VDRL) test. Sera which were reactive in the VDRL test were confirmed by the fluorescent treponemal antibody absorption (FTA-ABS) test. BFP reactions were detected in 0.59% of the general population, 0.72% of pregnant women and 11.8% of patients with systemic lupus erythematosus (SLE). The rate of BFP reactors among pregnant women did not differ significantly from the general population. The female to male ratio of BFP in the general population was 2:1 whilst that in the group of patients with SLE was 8:1. The overall seroprevalence of syphilis was 2.2%.
PMCID: PMC1194464  PMID: 2187794
23.  Serological Response to Treatment of Syphilis According to Disease Stage and HIV Status 
The serological response to treatment was studied in 264 syphilis patients; it was influenced by syphilis stage but not by human immunodeficiency virus infection and reinfection. Some of the recommendations of current guidelines are critically discussed, and amendments are proposed.
Background. Serology is the mainstay for syphilis diagnosis and treatment monitoring. We investigated serological response to treatment of syphilis according to disease stage and HIV status.
Methods. A retrospective cohort study of 264 patients with syphilis was conducted, including 90 primary, 133 secondary, 33 latent, and 8 tertiary syphilis cases. Response to treatment as measured by the Venereal Disease Research Laboratory (VDRL) test and a specific IgM (immunoglobulin M) capture enzyme-linked immunosorbent assay (ELISA; Pathozyme-IgM) was assessed by Cox regression analysis.
Results. Forty-two percent of primary syphilis patients had a negative VDRL test at their diagnosis. Three months after treatment, 85%–100% of primary syphilis patients had reached the VDRL endpoint, compared with 76%–89% of patients with secondary syphilis and 44%–79% with latent syphilis. In the overall multivariate Cox regression analysis, serological response to treatment was not influenced by human immunodeficiency virus (HIV) infection and reinfection. However, within primary syphilis, HIV patients with a CD4 count of <500 cells/μL had a slower treatment response (P = .012). Compared with primary syphilis, secondary and latent syphilis showed a slower serological response of VDRL (P = .092 and P < .001) and Pathozyme-IgM tests (P < .001 and P = .012).
Conclusions. The VDRL should not be recommended as a screening test owing to lack of sensitivity. The syphilis disease stage significantly influences treatment response whereas HIV coinfection only within primary syphilis has an impact. VDRL test titers should decline at least 4-fold within 3–6 months after therapy for primary or secondary syphilis, and within 12–24 months for latent syphilis. IgM ELISA might be a supplement for diagnosis and treatment monitoring.
PMCID: PMC3501331  PMID: 22955437
24.  Cerebrospinal Fluid Abnormalities in HIV-Negative Patients with Secondary and Early Latent Syphilis and Serum VDRL ≥ 1:32 
Syphilis is caused by a spirochete Treponema pallidum. Invasion of the central nervous system (CNS) by T. pallidum may appear early during the course of disease. The diagnosis of confirmed neurosyphilis is based on the reactive Venereal Disease Research Laboratory (VDRL) in cerebrospinal fluid (CSF). Recent studies indicated that serum RPR ≥ 1:32 are associated with higher risk of reactivity of CSF VDRL.
The main aim of the current study was to assess cerebrospinal fluid serological and biochemical abnormalities in HIV negative subjects with secondary and early latent syphilis and serum VDRL ≥ 1:32.
Materials and Methods:
Clinical and laboratory data of 33 HIV-negative patients with secondary and early latent syphilis, with the serum VDRL titer ≥ 1:32, who underwent a lumbar puncture and were treated in Department of Dermatology at Jagiellonian University School of Medicine in Cracow, were collected.
Clinical examination revealed no symptoms of CNS involvement in all patients. 18% (n = 6) of patients met the criteria of confirmed neurosyphilis (reactive CSF-VDRL). In 14 (42%) patients CSF WBC count ≥ 5/ul was found, and in 13 (39%) subjects there was elevated CSF protein concentration (≥ 45 mg/dL). 10 patients had CSF WBC count ≥ 5/ul and/or elevated CSF protein concentration (≥ 45 mg/dL) but CSF-VDRL was not reactive.
Indications for CSF examination in HIV-negative patients with early syphilis are the subject of discussion. It seems that all patients with syphilis and with CSF abnormalities (reactive serological tests, elevated CSF WBC count, elevated protein concentration) should be treated according to protocols for neurosyphilis. But there is a need for identification of biomarkes in order to identify a group of patients with syphilis, in whom risk of such abnormalities is high.
PMCID: PMC3726894  PMID: 23919017
Cerebrospinal fluid examination; early syphilis; neurosyphilis
25.  Role of the Venereal Disease Research Laboratory test in the detection of syphilis. 
Of 9733 consecutive serological samples received by Portsmouth and Southampton Public Health Laboratories (PHL) and tested for syphilis, 190 (140 from men and 50 from women) gave positive results. Thirty new cases of syphilis were identified. Most sera were tested initially by both a specific antibody test (the Treponema pallidum haemaglutination (TPHA) test) and a cardiolipin test (the Venereal Disease Research Laboratory (VDRL) test). Among the 14 patients whose sera gave VDRL-positive but TPHA-negative results, 12 sera gave false-positive results. The sera of 90 patients gave TPHA-positive but VDRL-negative results; sera from only seven of these patients gave false-positive results. The VDRL test is very unlikely to identify a new case of syphilis where a TPHA test has failed to do so. The results of the survey suggest that the VDRL test should be withdrawn from initial testing for syphilis except where early primary disease is suspected.
PMCID: PMC1046122  PMID: 6337682

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