Utility of the Determine Syphilis TP rapid test in commercial sex venues in Peru
- P E Campos1,
- A L Buffardi2,
- M Chiappe1,
- C Buendía1,
- P J Garcia1,
- C P Carcamo1,
- G Garnett3,
- P White3,
- K K Holmes2,*
- 1Unidad de Epidemiología, Enfermedades de Transmisión Sexual y SIDA, Facultad de Salud Pública y Administración, Universidad Peruana Cayetano Heredia, Lima, Peru
- 2Center for AIDS & STD, Seattle, Washington, USA
- 3Department of Infectious Disease Epidemiology, Imperial College, London, UK
- Correspondence to: Professor King K Holmes UW Center for AIDS and STD, HMC, Box 359931, 325 – 9th Avenue, Seattle, WA 98104, USA; worthy{at}u.washington.edu
- Accepted 14 October 2006
- Published Online First 20 November 2006
Abstract
Objectives: This study sought to evaluate the utility of the Determine Syphilis TP test performed in Peruvian commercial sex venues for the detection of active syphilis; and determine the feasibility of integrating rapid syphilis testing for female sex workers (FSW) into existing health outreach services.
Methods: We tested 3586 female sex workers for syphilis by Determine in the field using whole blood fingerstick, and by rapid plasma reagin (RPR) and Treponema pallidum haemagglutination assay (TPHA) in a central laboratory in Lima using sera.
Results: 97.4% of the FSW offered rapid syphilis testing participated; and among those who tested positive, 87% visited the local health centre for treatment. More than twice as many specimens were RPR reactive using serum in Lima (5.7%) than tested positive by whole blood Determine in the field (2.8%), and although most were confirmed by TPHA, only a small proportion (0.7%) were RPR reactive at ≥1:8 dilutions, and likely indicating active syphilis. Sensitivity, specificity and positive predictive value of the Determine Syphilis TP test in whole blood when compared to serum RPR reactivity at any dilution confirmed by TPHA as the gold standard were 39.3%, 99.2% and 71.4%, respectively. Sensitivity improved to 64.0% when using serum RPR ≥1:8 confirmed by TPHA. Invalid tests were rare (0.3%).
Conclusions: Rapid syphilis testing in sex work venues proved feasible, but Determine using whole blood obtained by fingerstick was substantially less sensitive than reported in previous laboratory-based studies using serum. Although easy to perform in outreach venues, the utility of this rapid syphilis test was relatively low in settings where a large proportion of the targeted population has been previously tested and treated.
- CT, chlamydial infection
- FSW, female sex workers
- GC, gonorrhoea
- PCR, polymerase chain reaction
- PPV, positive predictive values
- PROCETSS, Peruvian Ministry of Health HIV/STI Control Program
- RPR, rapid plasma reagin
- STI, sexually transmitted infections
- TPHA, Treponema pallidum haemagglutination assay
- TPPA, Treponema pallidum particle agglutination assay
- TV, trichomoniasis
Footnotes
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↵* Also Department of Medicine, University of Washington, Seattle, Washington, USA
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Sources of support: Wellcome Trust-Burroughs Wellcome Fund Infectious Disease Initiative (059131/Z/99/Z), Wellcome Trust Health Consequences of Population Change (GR078835), University of Washington Center for AIDS Research (P30 AI 27757), and the UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases STD Diagnostics Initiative (donation of Determine Syphilis TP test kits).
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Competing interests: none declared
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The research protocol using human subjects in this study has been reviewed and approved by the Human Subject Review Committee of the University of Washington and the Ethical Committee of the Scientific Research Office at the Cayetano Heredia University
