Laboratory diagnosis and interpretation of tests for syphilis

Assessment of the rapid test based on an immunochromatography technique for detecting anti-Treponema pallidum antibodies

A rapid test based on an immunochromatography assay - Determine™ Syphilis TP (Abbott Lab.) for detecting specific antibodies to Treponema pallidum was evaluated against serum samples from patients with clinical, epidemiological and serological diagnosis of syphilis, patients with sexually transmitted disease other than syphilis, and individuals with negative serology for syphilis. The Determine™ test presented the sensitivity of 93.6%, specificity of 92.5%, and positive predictive value and negative predictive value of 95.2% and 93.7%, respectively. One serum sample from patient with recent latent syphilis showed a prozone reaction. Determine™ is a rapid assay, highly specific and easy to perform. This technique obviates the need of equipment and its diagnostic features demonstrate that it may be applicable as an alternative assay for syphilis screening under some emergency conditions or for patients living in remote localities.

Syphilis and otolaryngology

Syphilis is the oldest known sexually transmitted disease. Because of its multiple clinical manifestations it is known as "the great imitator." Although the antibiotic era has greatly diminished the prevalence of syphilis, sporadic outbreaks continue to occur. Because of its multiple head and neck manifestations, the otolaryngologist should be familiar with the basic pathogenesis and clinical presentations of this disease.

Susceptibility of Treponema pallidum to host-derived antimicrobial peptides

LL-37 displays potent broad-spectrum activity against a number of pathogenic bacteria and is the only cathelicidin thus far identified in humans. In this study, we examined the capacity of human LL-37 and the similar CAP-18-derived peptide from rabbits to exert antimicrobial activity against the causative agent of syphilis, Treponema pallidum. We found that both peptides, as well as a truncated version of human LL-37 that contains its bactericidal domain, could exert rapid, but salt-sensitive antimicrobial activity against T. pallidum. Infectivity of T. pallidum in a rabbit model could effectively be blocked with the synthetic truncated LL-37-derived peptide WS22-N-amide.

Sexually transmitted diseases

Traditionally, STD is considered a disease of younger adults, and older adults continue to present a challenge to health care providers. Geriatric health care professionals must offer older adults adequate information relating to sexuality and aging. In addition, sexual health must be evaluated as a standard domain in routine comprehensive geriatric evaluation and management. Large-scale community education programs are helpful in encouraging cultural and societal acceptance of the sexuality of older adults. Finally, as baby-boomers age, health care professionals will face increasing pressure from their patients to address sexual health problems in geriatric clinical practice. The current dearth of relevant evidence-based information highlights the urgent need for prioritized research in this area.

Comparison of STD prevalences in the Mwanza, Rakai, and Masaka trial populations: the role of selection bias and diagnostic errors

OBJECTIVES

To assess bias in estimates of STD prevalence in population based surveys resulting from diagnostic error and selection bias. To evaluate the effects of such biases on STD prevalence estimates from three community randomised trials of STD treatment for HIV prevention in Masaka and Rakai, Uganda and Mwanza, Tanzania.

METHODS

Age and sex stratified prevalences of gonorrhoea, chlamydia, syphilis, HSV-2 infection, and trichomoniasis observed at baseline in the three trials were adjusted for sensitivity and specificity of diagnostic tests and for sample selection criteria.

RESULTS

STD prevalences were underestimated in all three populations because of diagnostic errors and selection bias. After adjustment, gonorrhoea prevalence was higher in men and women in Mwanza (2.8% and 2.3%) compared to Rakai (1.1% and 1.9%) and Masaka (0.9% and 1.8%). Chlamydia prevalence was higher in women in Mwanza (13.0%) compared to Rakai (3.2%) and Masaka (1.6%) but similar in men (2.3% in Mwanza, 2.7% in Rakai, and 2.2% in Masaka). Prevalence of trichomoniasis was higher in women in Mwanza compared to women in Rakai (41.9% versus 30.8%). Herpes simplex virus type 2 (HSV-2) seroprevalence and prevalence of serological syphilis (TPHA+/RPR+) were similar in the three populations but the prevalence of high titre syphilis (TPHA+/RPR >/=1:8) in men and women was higher in Mwanza (5.6% and 6.3%) than in Rakai (2.3% and 1.4%) and Masaka (1.2% and 0.7%).

CONCLUSIONS

Limited sensitivity of diagnostic and screening tests led to underestimation of STD prevalence in all three trials but especially in Mwanza. Adjusted prevalences of curable STD were higher in Mwanza than in Rakai and Masaka.

Etiology of genital ulcer disease and association with human immunodeficiency virus infection in two tanzanian cities

BACKGROUND

The etiological agent is usually not established in cases of genital ulcer disease (GUD) in Tanzania, since diagnosis and treatment of this disease are based mainly on clinical rather than microbiologic parameters. GUD increases the risk of infection with HIV. However, the association between specific GUD infections and HIV infection has not been fully investigated.

GOAL

The goal was to determine the etiology of GUD and the prevalence of HIV infection in patients with GUD in urban areas of Tanzania.

STUDY DESIGN

A total of 102 clinical specimens were collected from 52 and 50 patients with GUD in Dar es Salaam and Mbeya, respectively, and from 93 patients with genital discharge in a cross-sectional study. Two polymerase chain reaction (PCR) assays were used to identify either a single target DNA or all three DNAs of the major causes of GUD: Haemophilus ducreyi, Treponema palladum and herpes simplex virus type 2 (HSV-2). The sera from all patients were tested for antibodies to HIV and T palladum.

RESULTS

In Dar es Salaam, DNA from HSV-2, and was detected in 63%, 13%, and 2%, respectively, of the 52 genital ulcer specimens. The corresponding figures in Mbeya were 34%, 10%, and 0% of 50 specimens. Overall, 9% of the 102 patients with GUD were infected with both HSV-2 and, and 39/102 genital ulcer specimens (38%) were negative for the DNA of all three pathogens. The HIV infection rates among GUD patients were 46% and 52% in Dar es Salaam and Mbeya, respectively; among the non-GUD patients, the corresponding rates were 35% and 45%, respectively. The HIV infection rate in Dar es Salaam was significantly higher among women (11/14; 78%) than among men (13/38; 34%) (P = 0.004). Among the HIV-seropositive GUD patients, 71% and 46% (P < 0.003) were coinfected with HSV-2 in Dar es Salaam and Mbeya, respectively. Furthermore, women with HSV-2 in Dar es Salaam were significantly more likely to be HIV-infected than men (60% versus 39%; P<or= 0.006). antibodies were detected in 27 (26%) of the 102 GUD patients and 16 (17%) of the 93 non-GUD patients.

CONCLUSION

HSV-2 was the most commonly identified agent in the genital ulcer specimens in two urban STD clinics in Tanzania. The prevalence of HIV was high among the STD patients. HSV-2 was detected at significantly higher rates among HIV-seropositive than HIV-seronegative patients with GUD in both Dar es Salaam and Mbeya.

Evaluation of an enzyme immunoassay technique for detection of antibodies against Treponema pallidum

In the present study, the performance of an enzyme-linked immunosorbent assay (ELISA) technique (Eti-syphilis-G and Eti-syphilis-M; DiaSorin) for detection of Treponema pallidum immunoglobulin M (IgM) and IgG antibodies for the laboratory diagnosis of syphilis was evaluated. Four hundred forty-one samples were studied. The sensitivity and specificity of the ELISA were 100 and 93%, respectively, compared with the results of a microhemagglutination assay for Treponema pallidum (MHA-TP) and 99.4 and 100%, respectively, compared with the results of the fluorescent treponemal antibody absorption (FTA-Abs) test. The results of the ELISA technique were concordant with those of MHA-TP for 98% of the samples tested, while the rate of concordance with the FTA-Abs test was 99.5%. The sensitivities of the rapid plasma reagin (RPR) test, MHA-TP, and the ELISA in the different phases of syphilis compared with the results of the FTA-Abs test were 92, 88, and 100%, respectively, for patients with primary syphilis; 100% for all tests evaluated for patients with secondary syphilis; 97.2, 99.4, and 100%, respectively, for patients with latent syphilis; and 57.9, 92.6, and 97.9%, respectively, for patients with past treated syphilis. The RPR test was reactive with 12 samples that were negative by all the specific tests. IgM antibodies were most frequently detected by the ELISA for IgM antibodies (32.8%) than by the FTA-Abs for IgM antibodies (28.4%). Detection of these antibodies by the FTA-Abs test and the ELISA for IgM antibodies decreased with the stage of disease (72 and 88%, respectively, for patients with primary syphilis to 17 and 19%, respectively, for patients with early latent syphilis). The high sensitivity and specificity of this ELISA technique during all stages of syphilis, together with the fact that it is a simple, objective, and easily automated method, lead us to believe that it could be used as a screening test for syphilis.

Keratopathy from congenital syphilis

PURPOSE

Therapeutic decision-making in syphilitic corneal disease is discussed after seeing a patient with keratopathy from congenital syphilis.

METHODS

Case report and review of the literature.

RESULTS

Laboratory evaluation of our patient revealed a nonreactive serum rapid plasma reagin (RPR) test and a positive microhemagglutination assay-Treponema pallidum (MHA-TP) test.

CONCLUSION

Any patient with residual interstitial keratopathy, especially if bilateral, should be suspected to have congenital syphilis if the patient or parents were ever treated for a sexually transmitted disease, if stigmata of congenital syphilis are present, or if childhood ocular inflammation occurred.

Performance of the rapid plasma reagin and the rapid syphilis screening tests in the diagnosis of syphilis in field conditions in rural Africa

OBJECTIVES

To assess the rapid plasma reagin (RPR) test performance in the field and to evaluate a new rapid syphilis test (RST) as a primary screen for syphilis.

METHODS

1325 women of reproductive age from rural communities in the Gambia were tested for syphilis seropositivity using a RPR 18 mm circle card and a RST strip. Within 1 week a repeat RPR and a TPHA test were carried out using standard techniques in the laboratory.

RESULTS

Comparing field tests to a diagnosis of "active" syphilis defined as laboratory RPR and TPHA positive, the RPR test was 77.5% sensitive and 94.1% specific; the RST was 75.0% sensitive and 95.2% specific. The RST was easier to use and interpret than the RPR test especially where field conditions were difficult. In this setting with a low prevalence of syphilis in the community (3%), the chance of someone with a positive test being confirmed as having serologically active syphilis was less than 50% for both tests.

CONCLUSIONS

The appropriateness of syphilis screening using RPR testing in antenatal clinics and health centres should be questioned if there is a low prevalence in the population, conditions for testing are poor, and resources limited. There is still an urgent need for an appropriate rapid syphilis test for field use.

Comparison of a recombinant-antigen enzyme immunoassay with Treponema pallidum hemagglutination test for serological confirmation of syphilis

A recombinant-antigen enzyme immunoassay (EIA), BioSCREEN anti-Treponema pallidum, was compared favorably with the T. pallidum hemagglutination test, in the detection of specific antibodies in different groups of sera from patients with primary (n = 38), secondary (n = 10), early latent (n = 28) and congenital syphilis (n = 2), patients with leptospirosis ( n= 8), infectious mononucleosis (n = 7), hepatitis (n = 9), diabetes mellitus (n = 11), rheumatoid arthritis (n = 13), leprosy (n = 11), tuberculosis (n = 9), HIV/Aids ( n= 12), systemic lupus erythematosus (n = 4), rheumatic fever (n = 3), old-persons (n = 9), pregnant women (n = 29) and blood donors (n = 164). The coincidence between them was 95.1%. The sensitivity and specificity of the EIA were 93.3% and 95.5%, respectively. Fifteen serum specimens belonging to old-persons, pregnant women, blood donors, and patients with human leptospirosis, hepatitis, diabetes mellitus, tuberculosis and rheumatic fever gave false-positive results by Venereal Disease Research Laboratory and/or Rapid Plasma Reagin. The EIA can be used as alternative method for the serological confirmation of syphilis.

Screening for syphilis in arrestees: usefulness for community-wide syphilis surveillance and control

BACKGROUND

Syphilis screening of jail arrestees has been promoted as an effective method for both disease control and surveillance.

GOALS

To evaluate the yield of the East Baton Rouge Parish Jail screening program in detecting previously undiagnosed syphilis, to evaluate the program as a means for monitoring community syphilis rates, and to characterize arrestees at greatest risk for syphilis infection.

STUDY DESIGN

From July 1994 to December 1998, arrestees brought to the East Baton Rouge Parish Jail were screened for syphilis. Annual early syphilis prevalence in screened arrestees was calculated and compared with the annual period prevalence of early syphilis in the general population of East Baton Rouge Parish, as reported by laboratories and health providers. A case-control study of cases detected at the jail from 1995 to 1997 and contemporary controls was conducted.

RESULTS

A total of 50,941 arrestees were booked into the East Baton Rouge Parish Jail, of whom 38,573 (76%) were screened for syphilis. Of the 38,573 arrestees screened, 494 (1.3%) were diagnosed with untreated syphilis. Of these, 299 (61%) were treated for syphilis before release. The estimated prevalence of early syphilis in arrestees decreased by 68% during the study period, from 0.79% in 1994 to 0.25% in 1998. During this time, the East Baton Rouge Parish community rates decreased by 79%, from 150 cases per 100,000 to 31 cases per 100,000. In female arrestees, a booking charge of prostitution was associated with syphilis (odds ratio [OR] 7.0; 95% CI, 1.5, 39.3). In male arrestees, a booking charge of felony theft was associated with syphilis (OR 4.8; 95% CI, 1.8, 13.8). However, only 15 (12%) of the early syphilis cases would have been detected if screening had been based on the booking charges found to be associated with syphilis in this study.

CONCLUSIONS

Routine syphilis screening and treatment in jail settings is feasible and identifies many persons with syphilis. Monitoring of syphilis prevalence among arrestees is a useful method for monitoring community prevalence of syphilis. Analysis of booking charges may be useful for determining factors associated with syphilis infection, but not for developing screening criteria.

Evaluation of INNO-LIA syphilis assay as a confirmatory test for syphilis

We evaluated the sensitivity and specificity of a new confirmatory test for treponemal antibodies, INNO-LIA Syphilis (Innogenetics NV, Ghent, Belgium), on a large number of sera from a clinical laboratory. This multiparameter line immunoassay (LIA) uses recombinant and synthetic polypeptide antigens derived from Treponema pallidum proteins. In a single-blinded cross-sectional retrospective study, 289 seronegative sera, 219 seropositive sera, and 23 sera with an indeterminate serological status for syphilis were analyzed. All sera were tested by the T. pallidum hemagglutination assay (TPHA), the immunoglobulin (IgG)-fluorescent T. pallidum absorption assay (IgG-FTA-ABS), and the Venereal Disease Research Laboratory (VDRL) test. In addition, some seropositive samples were analyzed by the 19S-IgM-FTA-ABS test, an enzyme immunoassay (IgM-EIA), and the MarDx immunoblotting assay. Based on a consensus diagnosis derived from conventional serology, all of the sera were classified as positive, negative, or indeterminate, and the results were compared with the findings of the INNO-LIA Syphilis assay. The sensitivity and specificity of the LIA were 100% (219 of 219) and 99.3% (286 of 288), respectively. Compared to TPHA and IgG-FTA-ABS, the new test gave a significantly higher number (P = 0.021 and P < 0.0001, respectively) of correct results than either of the other two tests. The multiparameter INNO-LIA Syphilis assay is a useful confirmatory test for syphilis because it increases the reliability of syphilis diagnosis with respect to current conventional techniques.

Papulosquamous disorders of the elderly

Several papulosquamous skin conditions occur in the elderly, including inherited and acquired ichthyoses, psoriasis, cutaneous lymphoma, and cutaneous connective tissue diseases. The clinical presentations can be quite helpful in diagnosing these conditions, and confirmatory histology and immunologic testing can often better define the specific entities. Treatment often involves identifying underlying systemic causes, as well as specific approaches based on the diagnosis and severity of clinical presentation.

Evaluation of the passive particle agglutination test in the serodiagnosis and follow-up of syphilis

We performed the present study to determine the rate of concordance of the fluorescent treponemal antibody absorption test (FTA-ABS) and of the microhemagglutination assay for antibodies to Treponema pallidum (MHA-TP) with the passive particle agglutination test (TP.PA) in patients with early syphilis and to observe the reactivity of the rapid plasma reagin (RPR), MHA-TP, and the TP.PA tests for 1 year after therapy. The study included 449 people who were given therapy if they had syphilis and followed up for 1 year. The rate of concordance of the TP.PA with the MHA-TP was 98.4%, and it was 98.9% with the FTA-ABS. During follow-up, a significant decrease of antibodies was found in 56%, 26%, and 70% of the patients when using the RPR, the MHA-TP, and the TP.PA, respectively. The TP.PA seems to be an adequate routine assay for the diagnosis of syphilis, being as sensitive as the FTA-ABS test in primary syphilis and as useful as the RPR test in monitoring therapy.

Absence of risk factors for false-positive test results in blood donors with a reactive test result in an automated treponemal test (PK-TP) for syphilis

BACKGROUND

Screening and confirmatory serologic tests for syphilis are known to generate false-positive results in low-risk populations, which include blood donors. This study assessed whether conditions previously reported to cause biological false-positive (BFP) test results for syphilis are relevant to contemporary syphilis testing of blood donors and the extent to which seropositive donors report a history of syphilis.

STUDY DESIGN AND METHODS

A history of conditions reported to be associated with BFP syphilis tests or a history of syphilis infection was assessed by a case-control study of donors with reactive and nonreactive automated treponemal test results, using an anonymous mail survey. Analysis of cases was stratified by fluorescent treponemal antibody absorption (FTA-ABS) result.

RESULTS

Adjusted ORs (95% CIs) for reported BFP-associated conditions were 1.3 (0.8-2.1) for FTA-ABS-positive cases and 0.8 (0.3-1.9) for FTA-ABS-negative cases. Among responding blood donors, syphilis history was reported in 78 (51%) of 153 FTA-ABS-positive cases, 0 of 142 FTA-ABS-negative cases, and 3 (0.4%) of 716 automated treponemal test (PK-TP)-negative controls.

CONCLUSION

Approximately half of donors with FTA-ABS-positive test results reported a syphilis history. There was no difference between reported BFP conditions for FTA-ABS-positive or FTA-ABS-negative cases and controls. This information may be useful when providing donors with better predonation or post-test counseling information about syphilis testing.

Western immunoblotting with five Treponema pallidum recombinant antigens for serologic diagnosis of syphilis

Five immunodominant Treponema pallidum recombinant polypeptides (rTpN47, rTmpA, rTpN37, rTpN17, and rTpN15) were blotted onto strips, and 450 sera (200 from blood donors, 200 from syphilis patients, and 50 potentially cross-reactive) were tested to evaluate the diagnostic performance of recombinant Western blotting (recWB) in comparison with in-house whole-cell lysate antigen-based immunoblotting (wclWB) and T. pallidum hemagglutination (MHA-TP) for the laboratory diagnosis of syphilis. None of the serum specimens from blood donors or from potential cross-reactors gave a positive result when evaluated by recWB, wclWB, or MHA-TP. The evaluation of the immunoglobulin G immune response by recWB in sera from patients with different stages of syphilis showed that rTmpA was the most frequently identified antigen (95%), whereas only 41% of the specimens were reactive to rTpN37. The remaining recombinant polypeptides were recognized as follows: rTpN47, 92.5%; rTpN17, 89.5%; and rTpN15, 67.5%. The agreement between recWB and MHA-TP was 95.0% (100% with sera from patients with latent and late disease), and the concordance between wclWB and MHA-TP was 92.0%. The overall concordance between recWB and wclWB was 97.5% (100% with sera from patients with secondary and late syphilis and 94.6 and 98.6% with sera from patients with primary and latent syphilis, respectively). The overall sensitivity of recWB was 98.8% and the specificity was 97.1% with MHA-TP as the reference method. These values for sensitivity and specificity were slightly superior to those calculated for wclWB (sensitivity, 97.1%, and specificity, 96.1%). With wclWB as the standard test, the sensitivity and specificity of recWB were 98.9 and 99.3%, respectively. These findings suggest that the five recombinant polypeptides used in this study could be used as substitutes for the whole-cell lysate T. pallidum antigens and that this newly developed recWB test is a good, easy-to-use confirmatory method for the detection of syphilis antibodies in serum.

New tests for syphilis: rational design of a PCR method for detection of Treponema pallidum in clinical specimens using unique regions of the DNA polymerase I gene

A sensitive and specific PCR method to detect Treponema pallidum in clinical specimens was developed. PCR primers were designed based on two unique features of the DNA polymerase I gene (polA). The first distinctive characteristic is that the region codes for a high cysteine content and has low homology with similar regions of DNA polymerase I gene from known microorganisms. The second unique feature is the presence of four insertions in the gene. PCR tests using primers designed on the basis these regions reacted with various pathogenic T. pallidum subspecies but did not react with nonpathogenic treponemal species or other spirochetes. An additional 59 species of bacteria and viruses, including those that cause genital ulcers, tested negative. This PCR method is extremely robust and sensitive. The detection limit is about 10 to 25 organisms when analyzed on gel. However, the analytic sensitivity can be increased by at least 1 log, to a detection limit of a single organism, when the ABI 310 Prism Genetic Analyzer is used to detect fluorescence-labeled amplicons. We further used this test in a clinical setting and compared the results with results from a previously reported multiplex-PCR test (for T. pallidum, Haemophilus ducreyi, and herpes simplex virus). We tested 112 genital ulcer specimens by the polA PCR, obtaining a sensitivity of 95.8% and a specificity of 95.7%. These results suggest that the polA PCR is applicable as a routine clinical diagnostic test for syphilis.

Evaluation of recomWell Treponema, a novel recombinant antigen-based enzyme-linked immunosorbent assay for the diagnosis of syphilis

OBJECTIVE

To evaluate the diagnostic performance of an enzyme immunosorbent assay (recomWell Treponema) for the diagnosis of syphilis. The novel recombinant antigens Tpn47, TpN17 and TpN15 were utilized.

METHODS

A total of 782 human serum specimens, belonging to four different categories (blood donors, n = 200; routine laboratory screening for syphilis, n = 400; syphilis patients, n = 122; potential cross-reactors, n = 60), were evaluated to compare the sensitivity and specificity of the recomWell Treponema kit with a standard whole Treponema pallidum cell lysate antigen-based ELISA (Syphilis Screening) and with micro-haemagglutination (MHA-TP).

RESULTS

The overall specificity and sensitivity of the recomWell Treponema IgG was 98.9% and 98.3%, respectively. The specificity and sensitivity of Syphilis Screening ELISA was 98.7% and 98.3%, respectively. The agreement between recomWell Treponema and Syphilis Screening was 100%, 97.8%, 95.9% and 95% among the blood donor specimens, screening samples, syphilis specimens and the potential cross-reactors, respectively. Values of concordance varying from 96.7% to 98.3% were found in the different groups of sera between recomWell Treponema and MHA-TP. In addition, recomWell Treponema demonstrated a good diagnostic performance when used to detect the IgM to T. pallidum. No false-positive sera were identified and, in 17/19 samples from primary infection, an IgM immune response was found.

CONCLUSIONS

recomWell Treponema was shown to be a highly specific and sensitive method in all stages of syphilis screening and it can be considered as alternative to other ELISA tests based on native antigen preparations.

Treponema pallidum western blot: comparison with the FTA-ABS test as a confirmatory test for syphilis

We developed a Treponema pallidum Western blot and compared the results with Treponema pallidum particle agglutination (TPPA) and fluorescent treponemal antibody absorption (FTA-ABS) tests. The Western blot was deemed reactive if the serum reacted with at least three major antigenic bands (TpN47, TpN44.5, TpN17, TpN15). The sensitivities of the Western blot, TPPA and FTA-ABS, were all 100% and the specificities of the Western blot, TPPA and FTA-ABS were 100%, 100% and 94.5% respectively. In 52 problem sera, reactive in only one treponemal test, the agreement between the Western blot and TPPA (61.5%) was significantly better than between Western blot and FTA-ABS (38.5%). The individual sensitivities and specificities of TpN47, TpN44.5, TpN17, TpN15 were 100%, 100%, 96%, 100% and 20%, 96%, 100%, 100% respectively. We conclude that the Western blot is a useful additional confirmatory test or alternative to the FTA-ABS and that a more sensitive and specific criterion for the Western blot would be reactivity with TpN15 and two of the three other major antigens.

First European exposure to syphilis: the Dominican Republic at the time of Columbian contact

Recognition of syphilis in Europe in the late 15th century and its prior absence suggest New World origin. Skeletal populations were examined from sites with documented Columbian contact in the Dominican Republic. Examination of 536 skeletal remains revealed periosteal reaction characteristic of treponemal disease in 6%-14% of the afflicted population. Findings were identical to that previously noted in confirmed syphilis-affected populations and distinctive from those associated with yaws and bejel: it was a low population frequency phenomenon, affecting an average of 1.7-2.6 bone groups, often asymmetric and sparing hands and feet, but associated with significant tibial remodeling. While findings diagnostic of syphilis have been reported in the New World, actual demonstration of syphilis in areas where Columbus actually had contact was missing, until now. The evidence is consistent with this site as the point of initial contact of syphilis and of its subsequent spread from the New World to the Old.

Comparison of the Serodia Treponema pallidum particle agglutination, Captia Syphilis-G, and SpiroTek Reagin II tests with standard test techniques for diagnosis of syphilis

We compared the microhemagglutination assay for Treponema pallidum (MHA-TP), a treponemal test, with two other treponemal tests, the Serodia Treponema pallidum particle agglutination (TP-PA) assay and the Captia Syphilis-G enzyme immunoassay, using 390 clinical serum samples. We also compared two nontreponemal tests, the rapid plasma Reagin (RPR) card test and the SpiroTek Reagin II test. Agreements of the MHA-TP with the TP-PA test and the Syphilis-G test were 97.4 and 97.7%, respectively. There was 89.2% agreement between the RPR and Reagin II tests. The Reagin II test was more apt to be reactive if the treponemal test was also reactive. We conclude that either the Serodia TP-PA test or the Captia Syphilis-G test is an appropriate substitute for the MHA-TP and that the Spirotek Reagin II test could substitute for the RPR test as a screening test.

Treponema pallidum surface immunofluorescence assay for serologic diagnosis of syphilis

A surface immunofluorescence assay (SIFA) using live spirochetes was analyzed and compared with Western blot (WB), fluorescent treponemal antibody absorption (FTA-ABS), microhemagglutination (MHA-TP), and Treponema pallidum immobilization (TPI) assays for detecting serum antibodies to T. pallidum in patients with syphilis, in disease controls, and in healthy subjects. SIFA and WB were 99% sensitive (99 of 100 positive specimens) and specific (140 of 140 negative specimens); FTA-ABS showed a sensitivity and a specificity of 90 and 89% (90 of 100 positive and 125 of 140 negative specimens), respectively. MHA-TP showed a sensitivity of 84% (84 of 100 positive specimens) and a specificity of 98.5% (138 of 140 negative specimens). Finally, TPI had a sensitivity of 52% (52 of 100 positive specimens) and a specificity of 100% (140 of 140 negative specimens). The T. pallidum SIFA was therefore highly specific, showing no equivocal reactivities with control sera, and sensitive. The results suggest the possible use of SIFA as a confirmatory test in the serologic diagnosis of syphilis.

Syphilis testing

The organism that causes syphilis, Treponema pallidum, is impossible to culture in the clinical laboratory. Direct visualization of the pathogen is one laboratory technique used in the diagnosis of syphilis. Currently, serologic testing is the most widely used laboratory technique in diagnosing syphilis and monitoring its course after treatment. Serologic tests are divided into two categories, the nontreponemal and treponemal antibody tests. Newer techniques such as enzyme immunoassays have shown excellent results.

Comparative evaluation of nine different enzyme-linked immunosorbent assays for determination of antibodies against Treponema pallidum in patients with primary syphilis

Nine different enzyme-linked immunosorbent assays (ELISAs) with a sonicate or recombinant proteins of Treponema pallidum as antigen have been evaluated comparatively by testing 52 highly selected sera from patients with primary syphilis, all negative in the microhemagglutination test for T. pallidum (MHA-TP). Eight tests exhibited greater sensitivity (48.5 to 76.9%) than the commonly used Venereal Disease Research Laboratory test (44.2%). Higher sensitivity could be related to (i) the volume and dilution of the serum, (ii) the design of the assay (capture and competitive tests showed higher sensitivity than sandwich-based assays), and (iii) the ability to detected specific immunoglobulin M antibodies. The specificity of the ICE Syphilis and the Enzygnost Syphilis tests was 99.5 and 99.8%, respectively, as determined by routine testing of 2, 053 unselected sera in comparison with the MHA-TP test. ELISAs tested offered high sensitivity in patients with primary syphilis; however, recommendations to use these tests as screening assays do need further data on specificity and reactivity in late stages of the disease.

Comparative genome analysis of the pathogenic spirochetes Borrelia burgdorferi and Treponema pallidum

A comparative analysis of the predicted protein sequences encoded in the complete genomes of Borrelia burgdorferi and Treponema pallidum provides a number of insights into evolutionary trends and adaptive strategies of the two spirochetes. A measure of orthologous relationships between gene sets, termed the orthology coefficient (OC), was developed. The overall OC value for the gene sets of the two spirochetes is about 0.43, which means that less than one-half of the genes show readily detectable orthologous relationships. This emphasizes significant divergence between the two spirochetes, apparently driven by different biological niches. Different functional categories of proteins as well as different protein families show a broad distribution of OC values, from near 1 (a perfect, one-to-one correspondence) to near 0. The proteins involved in core biological functions, such as genome replication and expression, typically show high OC values. In contrast, marked variability is seen among proteins that are involved in specific processes, such as nutrient transport, metabolism, gene-specific transcription regulation, signal transduction, and host response. Differences in the gene complements encoded in the two spirochete genomes suggest active adaptive evolution for their distinct niches. Comparative analysis of the spirochete genomes produced evidence of gene exchanges with other bacteria, archaea, and eukaryotic hosts that seem to have occurred at different points in the evolution of the spirochetes. Examples are presented of the use of sequence profile analysis to predict proteins that are likely to play a role in pathogenesis, including secreted proteins that contain specific protein-protein interaction domains, such as von Willebrand A, YWTD, TPR, and PR1, some of which hitherto have been reported only in eukaryotes. We tentatively reconstruct the likely evolutionary process that has led to the divergence of the two spirochete lineages; this reconstruction seems to point to an ancestral state resembling the symbiotic spirochetes found in insect guts.

Clinical management and prevention of sexually transmitted diseases: a review focusing on women

This review highlights some of the difficulties inherent in controlling sexually transmitted diseases (STDs) in developing countries--especially amongst women. Considerable efforts have been made to improve the syndromic approach to STD management but the poor performance of the algorithm for managing vaginal discharge limits the effectiveness of this strategy. The facilitating role of the human immunodeficiency virus (HIV) has been the main impetus to STD control rather than reduction of morbidity in women, especially pregnant women and their children. There are no easy solutions--but action on several fronts, with more attention to core groups, men and adolescents is indicated.

Clinical utility of a competitive ELISA to detect antibodies against Treponema pallidum

Screening for Treponema pallidum infection is carried out on a large human population. To reduce costs, fewer tests which still offer adequate sensitivity and specificity could be performed. We studied the reliability of a novel indirect ELISA method to test for this infection. Several panels of sera were used that corresponded to 40 primary infections (group 1), 13 recurrences (group 2), 348 latent infections (group 3), 5 samples with anticardiolipin antibodies (group 4), 15 samples from patients with Lyme borreliosis (group 5), and 400 samples from blood donors and healthy pregnant women (group 6). The ELISA showed a global sensitivity and specificity of 100 and 99.5%, respectively. Our evaluation shows that Enzygnost Syphilis is a sensitive, specific, and simple test to screen for this infection.

The Use of Molecular Techniques for the Diagnosis and Epidemiologic Study of Sexually Transmitted Infections

Molecular diagnostic tests are more sensitive and, in many cases, more specific than conventional laboratory methods for the detection of sexually transmitted infections. Here, we review recently developed molecular methods for the diagnosis and subtyping of the most common sexually transmitted infections: infections caused by Chlamydia trachomatis, Neisseria gonorrhoeae, human papillomavirus, Trichomonas vaginalis, and the agents of genital ulcer disease (Haemophilus ducreyi, herpes simplex virus, Treponema pallidum, and Calymmatobacterium granulomatis). We also provide an overview of the laboratory diagnostic tests and clinical specimens to use when infection with these agents is suspected.

Validation of the INNO-LIA syphilis kit as a confirmatory assay for Treponema pallidum antibodies

The commercially available diagnostic tests for syphilis are mostly based on the use of extracted antigens of Treponema pallidum. Pronounced cross-reactivities with other spirochete antigens are often reported. The aim of this study was to validate a novel multiparametric assay (the assay performed with the kit) INNO-LIA Syphilis for the confirmation of syphilis antibodies in a set of 840 documented human serum samples. All serum samples were previously tested at the French World Health Organization reference center for venereal diseases (Institute Alfred Fournier, Paris, France), with a consensus result provided for each sample. The study was conducted in two phases, with each phase involving a validation set (500 well-documented serum samples) and an exploratory set (340 serum samples) of serum samples, respectively. By measuring the sensitivity and specificity, we compared the result of the new assay with the consensus result on the basis of the results of a variable number of classical serological methods and clinical information when available. A sensitivity of 99.6% (95% confidence internal [CI], 98.5 to 99.9%) and a specificity of 99.5% (95% CI, 98.1 to 99.9%) were found for the new line immunoassay. Six of seven samples with indeterminate results by classical serology tested positive with the INNO-LIA Syphilis kit. This single multiparametric assay provides reliable confirmatory diagnostic information that must currently be obtained by the performance and interpretation of results of a combination of serological assays.

Syphilis serology and HIV infection in Harare, Zimbabwe

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.

An unexpected result in an evaluation of a serological test to detect syphilis

Traditional tests for detection of syphilis are labour intensive and costly. Enzyme immunoassays (EIAs) are readily automated and cost effective if large numbers of tests are performed. Four experiments were devised to evaluate a syphilis EIA test kit where resources are limited: (1) testing antenatal patients; (2) testing refugees; (3) testing a high prevalence population; and (4) testing "problem sera" (containing autoantibodies or antibodies to other infective agents). Forty-one available syphilitic sera from antenatal patients were tested to evaluate sensitivity. Specificity was determined through testing sera determined to be nonreactive with rapid plasma reagin and Treponema pallidum hemagglutination tests, calculating the sample size (456) on the confidence interval (CI) required. Two runs were performed on antenatal sera, giving sensitivities of 32% (95% CI: 20%, 47%) and 37% (95% CI: 24%, 52%) and specificities of 92% (95% CI: 89%, 94%) and 90% (95% CI 87%, 92%), respectively. We present a method to evaluate a serological test where resources are limited. Unexpectedly, the test kit performed poorly as a screening test. New serological tests need to be evaluated in-house prior to adoption.

Laboratory methods of diagnosis of syphilis for the beginning of the third millennium

Despite that the whole genome of T. pallidum, the causative agent of syphilis, has been sequenced, syphilis is, and will remain for some time, diagnosed by direct clinical observation and by laboratory methods. This review presents comprehensively most of the practical techniques used for direct detection of T. pallidum and lists all practical methods for phospholipid and treponemal antibodies detection. It describes most novel tests for syphilis, discusses problems with sero-creossreactivity in Lyme disease, immune responses in HIV-syphilis coinfected patients, and reviews serologic responses to antibiotic treatment.

Syphilis, gonorrhoea, and drug abuse among pregnant women in Jefferson County, Alabama, US, 1980-94: monitoring trends through systematically collected health services data

OBJECTIVE

To assess the association between self reported drug abuse and syphilis and gonorrhoea among pregnant women, Jefferson County, Alabama, United States, 1980-94.

STUDY DESIGN

We analysed a prenatal care database and assessed the association of self reported drug use with seropositive syphilis and gonorrhoea using prevalence rates, multiple logistic regression models, and the Pearson correlation coefficient (r) for trends.

RESULTS

Overall, 5.5% of the women acknowledged drug abuse, 1.4% had seropositive syphilis, and 4.8% had gonorrhoea. In a multivariate analysis, drug abuse was associated with syphilis (odds ratio 2.9, 95% confidence interval 1.6, 5.3) but not with gonorrhoea. Trends in the annual prevalence of drug abuse closely paralleled trends in the annual prevalence of syphilis, including simultaneous peaks in 1992 (drug abuse, 9.1%; syphilis, 3.2%). There was no such parallel trend between drug abuse and gonorrhoea. Annual prevalence of drug abuse correlated with the prevalence of syphilis (r = 0.89, p = 0.001) more than with the prevalence of gonorrhoea (r = 0.45, p = 0.201).

CONCLUSION

Among pregnant women, an increase in drug abuse was closely associated with an epidemic of syphilis, but not of gonorrhoea. Systematically collected prenatal care data can usefully supplement surveillance of diseases and behavioural risk factors associated with them.

Syphilis: review with emphasis on clinical, epidemiologic, and some biologic features

Syphilis is a chronic disease with a waxing and waning course, the manifestations of which have been described for centuries. It occurs worldwide, and the incidence varies significantly with geographic location. Transmission is mainly by sexual contact. The causative organism, Treponema pallidum, was first described in 1905, but because of the inability to culture the organism and the limitations of direct microscopy, serologic testing is the mainstay of laboratory diagnosis. The disease has been arbitrarily divided into several stages. The primary stage is defined by a chancre at the site of inoculation. The secondary stage is characterized by a polymorphic rash, lymphadenopathy, and other systemic manifestations. A variable asymptomatic latent period follows, which for epidemiologic purposes is divided into early (<1 year) and late (>1 year) stages. The early stages (primary, secondary, and early latent) are potentially infectious. The tertiary stage is the most destructive and is marked by cardiovascular and neurologic sequelae and gummatous involvement of any organ system. Congenital infection may result in protean early or late manifestations. Unlike many other bacteria causing infectious diseases, the organism remains sensitive to penicillin, and this remains the mainstay of therapy.

IgG western blot as a confirmatory test in early syphilis

Sensitivity and specificity of IgG detection by Western blotting performed with a lysate of Treponema pallidum whole cells were compared with those of the most common assays used in the laboratory diagnosis of syphilis, i.e. fluorescent treponemal antibody absorption test (FTA-ABS) and treponemal haemagglutination assay (TPHA). Thirty-five serum samples obtained from twenty-one patients with a clinical diagnosis of early syphilis, based on the presence of typical chancre or skin or mucous membrane lesions, were studied. In addition, thirty blood samples from donors, ten sera positive for Borrelia burgdorferi and five positive for Leptospira interrogans were tested as controls. The clinical diagnosis was the reference method used to compare the performance of the serological tests. Western blotting performed with a sensitivity and specificity of 100%, whereas the corresponding sensitivity and specificity for FTA-ABS were 88.5% and 98%, respectively. The performance of TPHA showed a sensitivity of 86% and a specificity of 100%.

Predictive value of past and current screening tests for syphilis in blood donors: changing from a rapid plasma reagin test to an automated specific treponemal test for screening

BACKGROUND

This study evaluated the change from a rapid plasma reagin (RPR) test to an automated specific treponemal test (PK-TP) in screening for syphilis in blood donors.

STUDY DESIGN AND METHODS

A cross-sectional seroprevalence analysis was performed on 4,878,215 allogeneic blood donations from 19 American Red Cross Blood Services regions from May 1993 through September 1995. Positive predictive values relative to the confirmatory fluorescent treponemal antibody absorption test (FTA-ABS) were calculated. Differences in seroprevalence were compared in RPR and PK-TP tests for 1) unconfirmed and confirmed tests, 2) first-time and repeat donors, and 3) "recent" versus "past" infections. Donation data from three additional Red Cross regions were evaluated for repeat donation patterns of blood donors who had a donation that was positive in a serologic screening test for syphilis. The value of RPR and PK-TP tests as surrogate markers for HIV infection was compared.

RESULTS

Reactive rates were lower but the positive predictive values was higher for the PK-TP test than for the RPR test. Initially, donors screened by PK-TP were more likely to be confirmed as positive than were donors screened by RPR, but these rates became comparable. It is estimated that a single HIV window-period donation was removed by serologic testing for syphilis each year of this study period.

CONCLUSIONS

The change to the PK-TP test resulted in a lower repeatedly reactive rate, better prediction that a confirmed-positive test for syphilis would occur in testing in the FTA-ABS, fewer donations lost, and comparable deferral rates. Because of the high rate of reactivity to serologic testing for syphilis among donors previously confirmed positive for syphilis, indefinite deferral after a confirmed-positive index donation may be warranted. Serologic testing for syphilis is ineffective as a marker of HIV-infectious window-period donations.

Bayes' theorem-based assessment of VDRL syphilis screening miss rates

BACKGROUND AND OBJECTIVES

Interlaboratory differences (and conflicting practices) in syphilis screening strategies (serial versus parallel test combinations) prompted us to determine an estimate of the diagnostic miss rate in the detection of (1) infected persons and (2) infected but untreated persons potentially affected by late active syphilis.

GOAL

We set out to establish the most efficient syphilis screening strategy for two routine tests (VDRL and Treponema pallidum hemagglutination assay [TPHA]) with regard to our tested public health population (average VDRL+ TPHA+ and VDRL- TPHA+ reactor ages being 59.9 years and 50.5 years, respectively.

STUDY DESIGN

Retrospective analysis covered the results of a routine parallel VDRL and TPHA testing on 24,863 persons done in four public health laboratories. Nosologic sensitivity of the VDRL test (18.32%) was determined using the TPHA test as reference. The percentage of VDRL nonreactors among infected persons (TPHA reactors) was considered as the VDRL false negative rate (81.68%). We estimated the proportion of persons infected but untreated with potential late active syphilis using our own Bayes theorem-based procedure.

RESULTS

The Bayes theorem-based estimate showed a significantly higher value for persons at risk of active late syphilis than the number of suspected cases obtained using the classical approach (25.1% versus 18.32%, or 83 persons versus 61 of the 330 infected).

CONCLUSION

In screening an older population, the VDRL test alone (or as the first of a series with TPHA as a confirmation test) may produce a diagnostic miss rate higher than the syphilis detection rate. Another miss in such a population is detected by the Bayes theorem-based method.