Performance of routine syphilis serology in the Ethiopian cohort on HIV/AIDS

Investigating latent syphilis in HIV treatment-experienced Ethiopians and response to therapy

Objectives

We investigated people with HIV (PWH) receiving combination antiretroviral therapy (cART) for latent syphilis infection prevalence, risk factors, treatment response, and neurosyphilis.

Methods

A prospective follow-up study was conducted on PWH and latent syphilis. The cases were randomly assigned to receive either benzathine penicillin G (BPG) or doxycycline (DOXY), and the posttreatment response was evaluated after 12 and 24 months. The traditional algorithm was used for serodiagnosis, and a semi-quantitative rapid plasma reagin (RPR) test monitored disease activity and treatment effectiveness.

Results

Of the 823 participants, 64.8% were women, and the mean age was 41.7±10 years. Thirty-one (3.8%) of the participants (22 males and nine females) had latent syphilis. The risk factors were male sex (aOR = 3.14), increasing age (aOR = 1.04 per year), and cART duration (aOR = 1.01 per month). Baseline RPR titers were: ≤1:4 in 19 (61.3%), between 1:8 and 1:32 in 10 (32.2%), and >1:32 in 2 (6.4%). None of the seven cerebrospinal fluid analyses supported a neurosyphilis diagnosis. In the 12^th month of treatment, 27 (87.1%) had adequate serological responses, three (9.7%) had serological nonresponse, and one (3.2%) had treatment failure. Syphilis treatment was repeated in the last four cases with the alternative drug. In terms of adequate serologic response, both therapies were comparable at the 12^th month, p = 0.37. All cases responded to treatment in the 24^th month.

Conclusion

In PWH receiving cART, latent syphilis occurred more in men than women, suggesting an investigation of sexual practices and the impact of antenatal syphilis screening. Syphilis disease activity reduces in the latent stage. Therefore, the routine cerebrospinal fluid analysis contributes little to the diagnosis of asymptomatic neurosyphilis and the treatment success of latent syphilis. DOXY is an alternative to BPG, and cART improves serologic response to latent syphilis treatment.

Incidence of syphilis seroconversion among HIV-infected persons in Asia: results from the TREAT Asia HIV Observational Database

INTRODUCTION

Outbreaks of syphilis have been described among HIV-infected men who have sex with men (MSM) in Western communities, whereas reports in Asian countries are limited. We aimed to characterize the incidence and temporal trends of syphilis among HIV-infected MSM compared with HIV-infected non-MSM in Asian countries.

METHODS

Patients enrolled in the TREAT Asia HIV Observational Database cohort and with a negative non-treponemal test since enrolment were analyzed. Incidence of syphilis seroconversion, defined as a positive non-treponemal test after previously testing negative, was evaluated among patients at sites performing non-treponemal tests at least annually. Factors associated with syphilis seroconversion were investigated at sites doing non-treponemal testing in all new patients and subsequently testing routinely or when patients were suspected of having syphilis.

RESULTS

We included 1010 patients from five sites that performed non-treponemal tests in all new patients; those included had negative non-treponemal test results during enrolment and subsequent follow-ups. Among them, 657 patients were from three sites conducting regular non-treponemal testing. The incidence of syphilis seroconversion was 5.38/100 person-years (PY). Incidence was higher in MSM than non-MSM (7.64/100 PY vs. 2.44/100 PY, p<0.001). Among MSM, the incidence rate ratio (IRR) for every additional year from 2009 was 1.19 (p=0.051). MSM status (IRR 3.48, 95% confidence interval (CI) 1.88-6.47), past syphilis diagnosis (IRR 5.15, 95% CI 3.69-7.17) and younger age (IRR 0.84 for every additional 10 years, 95% CI 0.706-0.997) were significantly associated with syphilis seroconversion.

CONCLUSIONS

We observed a higher incidence of syphilis seroconversion among HIV-infected MSM and a trend to increasing annual incidence. Regular screening for syphilis and targeted interventions to limit transmission are needed in this population.

The cost-effectiveness of 10 antenatal syphilis screening and treatment approaches in Peru, Tanzania, and Zambia

Objective

Rapid plasma reagin (RPR) is frequently used to test women for maternal syphilis. Rapid syphilis immunochromatographic strip tests detecting only Treponema pallidum antibodies (single RSTs) or both treponemal and non-treponemal antibodies (dual RSTs) are now available. This study assessed the cost-effectiveness of algorithms using these tests to screen pregnant women.

Methods

Observed costs of maternal syphilis screening and treatment using clinic-based RPR and single RSTs in 20 clinics across Peru, Tanzania, and Zambia were used to model the cost-effectiveness of algorithms using combinations of RPR, single, and dual RSTs, and no and mass treatment. Sensitivity analyses determined drivers of key results.

Results

Although this analysis found screening using RPR to be relatively cheap, most (> 70%) true cases went untreated. Algorithms using single RSTs were the most cost-effective in all observed settings, followed by dual RSTs, which became the most cost-effective if dual RST costs were halved. Single test algorithms dominated most sequential testing algorithms, although sequential algorithms reduced overtreatment. Mass treatment was relatively cheap and effective in the absence of screening supplies, though treated many uninfected women.

Conclusion

This analysis highlights the advantages of introducing RSTs in three diverse settings. The results should be applicable to other similar settings.

The trade-off between accuracy and accessibility of syphilis screening assays

The availability of rapid and sensitive methods to diagnose syphilis facilitates screening of pregnant women, which is one of the most cost-effective health interventions available. We have evaluated two screening methods in Tanzania: an enzyme immunoassay (EIA), and a point-of-care test (POCT). We evaluated the performance of each test against the Treponema pallidum particle agglutination assay (TPPA) as the reference method, and the accessibility of testing in a rural district of Tanzania. The POCT was performed in the clinic on whole blood, while the other assays were performed on plasma in the laboratory. Samples were also tested by the rapid plasma Reagin (RPR) test. With TPPA as reference assay, the sensitivity and specificity of EIA were 95.3% and 97.8%, and of the POCT were 59.6% and 99.4% respectively. The sensitivity of the POCT and EIA for active syphilis cases (TPPA positive and RPR titer ≥ 1/8) were 82% and 100% respectively. Only 15% of antenatal clinic attenders in this district visited a health facility with a laboratory capable of performing the EIA. Although it is less sensitive than EIA, its greater accessibility, and the fact that treatment can be given on the same day, means that the use of POCT would result in a higher proportion of women with syphilis receiving treatment than with the EIA in this district of Tanzania.

Syphilis and HIV co-infection in an Israeli HIV clinic: incidence and outcome

The re-emergence of syphilis among HIV-infected patients has been reported in recent years. We evaluated co-infection among heterosexual immigrants in an Israeli AIDS center. The records of 1060 HIV-infected patients were evaluated for positive syphilis serology between the years 2000 and 2005, and all seropositive patients were further evaluated. We found 150 HIV/syphilis co-infected patients (57% men, 93% of African origin), of who 135 were found to have late latent syphilis. Lumbar puncture (LP) was performed in 51 patients, 16 (31%) had abnormal cerebrospinal fluid (CSF) compatible with neurosyphilis. Abnormal CSF correlated with the absence of previous anti-syphilis treatment, but not with CD4 count, viral load or Venereal Disease Research Laboratory titres. Penicillin was recommended to all patients according to their disease stages and 81 patients completed 12 months post-treatment follow-up. Twenty-one of 81 (26%) treatments were successful, 33 (41%) showed 'serofast reaction' and 27 (33%) failed therapy. In conclusion, a high incidence of syphilis with CSF reactivity suggestive of neurosyphilis was observed in heterosexual Ethiopian HIV-infected patients. Thus, repeated serological screening and CSF evaluation seems to be indicated in these patients. Penicillin therapy resulted in 'serofast reaction' or treatment failure for most patients. More, intensive treatment might be needed for HIV/syphilis in co-infected patients, especially those with severe immune-deficiency and prolonged syphilis infection.

Evaluation of the LIAISON chemiluminescence immunoassay for diagnosis of syphilis

We report the results of an evaluation of the LIAISON Treponema pallidum-specific assay, a one-step sandwich chemiluminescence immunoassay (CLIA), as a screening test and as a confirmatory test for the diagnosis of syphilis. The assay was compared with the CAPTIA Syphilis-G enzyme immunoassay (EIA) and with a testing algorithm that also included the rapid plasma reagin (RPR) and T. pallidum particle agglutination (PA) assays. As a screening test, the CLIA showed levels of agreement with the EIA and with the algorithm, respectively, of 94.1 and 100% for 51 samples from patients with primary or secondary syphilis, 93.2 and 98.7% for 999 samples sent to the laboratory for routine syphilis testing, 84.5 and 94.0% for 200 samples from human immunodeficiency virus-positive patients, 98.0 and 100% for 200 samples from pregnant patients, and 94.3 and 98.3% for 992 samples from apparently healthy adults. As a confirmatory test, the CLIA showed 99% agreement with the EIA for 204 RPR-positive samples. After resolution with further T. pallidum PA testing and the discarding of one sample of insufficient quantity, there was 100% agreement for the remaining 203 samples. For the total group of 2,645 samples, the overall relative sensitivity was 95.8% and the relative specificity was 99.1%. We conclude that the LIAISON CLIA demonstrated excellent sensitivity and specificity when evaluated as a confirmatory test and as a screening test for syphilis among various patient populations, including specific populations with reportedly increased rates of false-positive nontreponemal test results.

Modelling the cost-effectiveness of introducing rapid syphilis tests into an antenatal syphilis screening programme in Mwanza, Tanzania

OBJECTIVES

A study found screening (with rapid plasma reagin (RPR)) pregnant women for maternal syphilis was cost-effective in Mwanza, Tanzania. Recently, four rapid point-of-care (POC) syphilis tests were evaluated in Mwanza, and found to have reasonable sensitivity/specificity. This analysis estimates the relative cost-effectiveness of using these POC tests in the Mwanza syphilis screening intervention.

METHODS

Empirical cost and epidemiological data were used to model the potential benefit of using POC tests instead of RPR. Reductions in costs relating to training, supplies, and equipment were estimated, and any changes in impact due to test sensitivity were included. Additional modelling explored how the results vary with prevalence of past infection, misclassified RPR results, and if not all women return for treatment.

RESULTS

The cost-effectiveness of using POC tests is mainly dependent on their cost and sensitivity for high titre active syphilis (HTAS). Savings due to reductions in training and equipment are small. Current POC tests may save more disability-adjusted life years (DALYs) than the RPR test in Mwanza, but the test cost needs to be <0.63 US dollars to be as cost-effective as RPR. However, the cost-effectiveness of the RPR test worsens by 15% if its HTAS sensitivity had been 75% instead of 86%, and by 25-65% if 20-40% of women had not returned for treatment. In such settings, POC tests could improve cost-effectiveness. Lastly, the cost-effectiveness of POC tests is affected little by the prevalence of syphilis, false RPR-positives, and past infections.

DISCUSSION

Although the price of most POC tests needs to be reduced to make them as cost-effective as RPR, their simplicity and limited requirements for electricity/equipment suggest their use could improve the coverage of antenatal syphilis screening in developing countries.

Why do we need quality-assured diagnostic tests for sexually transmitted infections?

The bacterial sexually transmitted infections (STIs) syphilis, gonorrhoea and chlamydia can all be cured with a single dose of antibiotic. Unfortunately, however, these infections often remain undiagnosed as many infected individuals have few if any symptoms. Diagnostic tests with high sensitivity and specificity are available for all three infections but, owing to their expense and the lack of laboratory capacity, most people in developing countries do not have access to these tests. There is a great need for simple, cheap diagnostic tests for STIs that can be performed at the point of care, enabling treatment to be given immediately. It is hoped that recent advances in our understanding of the pathogenesis of these infections, and the availability of the complete genome sequences for each causative organism, will lead to the development of improved point-of-care tests that will reduce the burden of these diseases in developing countries.

Why do we need quality-assured diagnostic tests for sexually transmitted infections?

The bacterial sexually transmitted infections (STIs) syphilis, gonorrhoea and chlamydia can all be cured with a single dose of antibiotic. Unfortunately, however, these infections often remain undiagnosed as many infected individuals have few if any symptoms. Diagnostic tests with high sensitivity and specificity are available for all three infections but, owing to their expense and the lack of laboratory capacity, most people in developing countries do not have access to these tests. There is a great need for simple, cheap diagnostic tests for STIs that can be performed at the point of care, enabling treatment to be given immediately. It is hoped that recent advances in our understanding of the pathogenesis of these infections, and the availability of the complete genome sequences for each causative organism, will lead to the development of improved point-of-care tests that will reduce the burden of these diseases in developing countries.

Effectiveness of syphilis treatment using azithromycin and/or benzathine penicillin in Rakai, Uganda

OBJECTIVE

The goal of this study was to assess azithromycin and/or benzathine penicillin for treatment of syphilis.

METHODS

In a population-based study, participants with serologic syphilis (TRUST with TPHA confirmation) were offered 2.4 MU benzathine penicillin intramuscularly. Intervention arm participants received 1 g presumptive oral azithromycin. We assessed cure rates with penicillin or azithromycin given alone and in combination. Cure assessed after 10 months was defined as seroreversion or a 4-fold decrease in titer. The rate ratio (RR) of cure and 95% confidence intervals (95% CIs) were estimated by log binomial regression.

RESULTS

Among 952 cases with syphilis, 18% received penicillin alone, 17% azithromycin only, and 65% dual treatment. The overall cure rate was 61%. Cure rates were lower in males compared with females (RR, 0.89; 95% CI, 0.80-0.99) and in subjects with initial titers > or =1:4 compared with < or =1:2 (RR, 0.77; 95% CI, 0.69-0.86). There was no significant differences in cure rates among HIV-positive and HIV-negative persons. With initial titers < or =1:2, there were no differences in cure rates by treatment regimen. However, with initial titers > or =1:4, significantly higher cure rates were observed with azithromycin alone (adjusted RR, 1.38; 95% CI, 0.97-1.96), and with dual treatment of azithromycin and benzathine penicillin (RR, 1.38; 95% CI, 1.03-1.87) compared with penicillin alone.

CONCLUSION

Azithromycin alone or in combination with penicillin achieved higher cure rates than penicillin alone in cases with a high initial TRUST titer. In low-titer infections, the 3 drug combinations were equally effective. HIV status did not affect cure rates.