We have completed a thorough review of the published literature on our RPR kit (code 222152) and would like to share the findings with you.

What is the clinical significance of the RPR test?

Syphilis is a chronic infection, caused by the spirochaete Treponema pallidum, which progresses through distinct stages of infection: primary, secondary, tertiary and quaternary. These stages produce diverse clinical symptoms, typically producing initial chancres then syphilitic rash followed by long periods of dormancy and may eventually lead to cardiovascular problems and neurosyphilis. Tests for syphilis fall into four categories: direct microscopic examination; treponemal antibody tests; non-treponemal antibody tests and direct antigen tests. Non-treponemal tests are useful to follow up antibiotic therapies. If the therapy is efficient, non treponemal titers will significantly decrease. RPR carbon is one such test.

What is the intended use of the RPR test?

The Cypress Diagnostics kit RPR Carbon is an in vitro diagnostic medical device intended to be used for the qualitative and/or semi-quantitative detection of Luetic reagins (non-treponemal antibodies) in human serum or plasma. The device is not automated. The detection of Luetic reagins is intended to be used to aid in the diagnosis of syphilis. This kit is intended to be used by healthcare professionals in a laboratory-based testing environment.

What does the literature review tell us?

The literature review identified 22 peer-reviewed studies published between 2011 and 2026 that document the use of the Cypress Diagnostics RPR Carbon kit across various clinical and public health settings, including blood donor screening, antenatal screening, STI/HIV clinics, high-risk populations, epidemiological surveillance, and population-based STI studies.

Published clinical data evaluating RPR Carbon in HIV-positive patients reported a comparison with TPHA, showing 92% sensitivity, 94% specificity, and a negative predictive value of 99% in that study population. (The negative predictive value indicates the probability that a negative test result is truly negative.)

Conclusion

These results provide clinical evidence supporting the use of Cypress Diagnostics RPR Carbon in syphilis testing algorithms.

The reviewed literature demonstrates that the Cypress Diagnostics RPR Carbon kit is clinically suitable in both routine clinical and public health settings. The evidence emphasizes its use in various testing scenarios, confirming its importance for laboratories conducting syphilis testing in these contexts.

Reference reading list / Liste de références

The following 22 peer-reviewed publications support the statements above. / Les 22 publications ci-dessous appuient les affirmations précédentes.

1. Hamill MM, Mbazira KJ, Kiragga AN, Gaydos CA, Jett-Goheen M, Parkes-Ratanshi R, et al. Challenges of rapid plasma reagin interpretation in syphilis screening in Uganda: Variability in nontreponemal results between different laboratories. Sex Transm Dis. 2018 Dec 1;45(12):829–33. doi:10.1097/OLQ.0000000000000883

2. Nakku-Joloba E, Kiragga A, Mbazira JK, Kambugu F, Jett-Goheen M, Ratanshi RP, et al. Clinical evaluation of 2 point-of-care lateral flow tests for the diagnosis of syphilis. Sex Transm Dis. 2016 Sep 15;43(10):623–5. doi:10.1097/OLQ.0000000000000498

3. Cassim S, Onyuthi RA, Muwanguzi E. Comparing CD4 counts in syphilitic and non-syphilitic HIV patients, Luwero District Uganda. Vol. 31. 2017;31.

4. Taylor MM, Ebrahim S, Abiola N, Kinkodi DK, Mpingulu M, Kabuayi JP, et al. Correlates of syphilis seropositivity and risk for syphilis-associated adverse pregnancy outcomes among women attending antenatal care clinics in the Democratic Republic of Congo. Int J STD AIDS. 2014 Jan 1;25(10):716–25. doi:10.1177/0956462413518194

5. Bisseye C, Sanou M, Nagalo BM, Kiba A, Compaoré TR, Tao I, et al. Epidemiology of syphilis in regional blood transfusion centres in Burkina Faso, West Africa. Pan Afr Med J. 2013;16:69. doi:10.11604/pamj.2013.16.69.2767

6. Dabire DE, Zongo SV, Ilboudo DP, Combari EJ, Yelemkoure ET, Sorgho AP, et al. Epidemiology of Hepatitis B and Syphilis in Ouagadougou (2013–2024): Screening, Prevalence and Drug Treatment. Am J Mol Biol. 2026;16(01):76–89. doi:10.4236/ajmb.2026.161007

7. Chomean S, Puttaruk P, Khamsophar P, Fukpo W, Kaset C. Evaluation of rapid diagnostic test kits for detection of Treponema pallidum antibody. PLoS One. 2024 May 1;19(5). doi:10.1371/journal.pone.0303477

8. Churiwal M, Kintu TM, Byamukama O, Bassett IV, Siedner MJ, Byamukama A, et al. HIV and Syphilis Coinfection in Pregnancy and Adverse Birth Outcomes in Uganda. J Infect Dis. 2026 Jan 17;233(1):197–205. doi:10.1093/infdis/jiaf453

9. Nagalo BM, Bisseye C, Sanou M. Diagnostic moléculaire du VIH sur les pools de plasmas de donneurs de sang au centre régional de transfusion sanguine de Ouagadougou (CRST-O), Burkina Faso. Med Trop. 2011;71:137–41.

10. Tagny CT, Nono Tagny O, Ngo Balogog P, Ndoumba A, Mbanya D. Performances du TPHA, RPR et du test rapide immuno-chromatographique dans le dépistage de la syphilis chez les donneurs de sang au CHU de Yaoundé, Cameroun. Transfus Clin Biol. 2016. p. 113–6. doi:10.1016/j.tracli.2015.11.003

11. Marcel MS, de Dieu LJ, Magloire CPS, Grésenguet G, Ralph-Sydney MB, Piette D, et al. Persistent high-risk behavior and escalating HIV, syphilis and hepatitis B incidences among men who have sex with men living in Bangui, Central African Republic. Pan Afr Med J. 2018;29. doi:10.11604/pamj.2018.29.132.12794

12. Musema GMA, Akilimali PZ, Za Balega TKN, Tshala-Katumbay D, Lusamba PSD. Predictive Factors of HIV-1 Drug Resistance and Its Distribution among Female Sex Workers in the Democratic Republic of the Congo (DRC). Int J Environ Res Public Health. 2022 Feb 1;19(4). doi:10.3390/ijerph19042021

13. Anamnart C, Tepkidakarn N. Prevalence of Neurosyphilis in Patients with Acute Ischemic Stroke: A Cross-Sectional Screening Study in Thailand. Trop Med Infect Dis. 2026 May 1;11(5). doi:10.3390/tropicalmed11050117

14. Simpore A, Kiba-Koumare A, Yooda AP, Sorgho AP, Zoure AA, Bazie VB, et al. Prevalence of serological markers for Hepatitis B and C Viruses, HIV and Treponema pallidum among blood donors in Ouagadougou, Burkina Faso. Int J Biol Chem Sci. 2022 Jun 9;16(1):13–22. doi:10.4314/ijbcs.v16i1.2

15. Alsughayyir J, Almalki Y, Alburayk I, Alalshaik M, Aljoni I, Kandel M, et al. Prevalence of transfusion-transmitted infections in Saudi Arabia blood donors: A nationwide, cross-sectional study. Saudi Med J. 2022 Dec 1;43(12):1363–72. doi:10.15537/smj.2022.43.12.20220634

16. Longo JDD, Simaleko MM, Diemer HSC, Grésenguet G, Brücker G, Belec L. Risk factors for HIV infection among female sex workers in Bangui, Central African Republic. PLoS One. 2017 Nov 1;12(11). doi:10.1371/journal.pone.0187654

17. Tao I, Bisseye C, Nagalo BM, Sanou M, Kiba A, Surat G, et al. Screening of hepatitis G and Epstein-Barr viruses among voluntary non-remunerated blood donors (VNRBD) in Burkina Faso, West Africa. Mediterr J Hematol Infect Dis. 2013;5(1):1–5. doi:10.4084/MJHID.2013.053

18. Nagalo BM, Bisseye C, Sanou M, Kienou K, Nebié YK, Kiba A, et al. Seroprevalence and incidence of transfusion-transmitted infectious diseases among blood donors from regional blood transfusion centres in Burkina Faso, West Africa. Trop Med Int Health. 2012 Feb;17(2):247–53. doi:10.1111/j.1365-3156.2011.02902.x

19. Nagalo MB, Sanou M, Bisseye C, Kaboré MI, Nebie YK, Kienou K, et al. Seroprevalence of HIV, hepatitis B and C viruses and syphilis among blood donors in Koudougou (Burkina Faso) in 2009. Blood Transfus. 2011;9(4):419–24. doi:10.2450/2011.0112-10

20. Mutricy-Hureau L, Pisoni A, Suarez-Mutis M, da Silva AF, Lambert Y, Mespoulhe P, et al. Sexual and addictive risk behaviors and sexually transmitted infections in illegal gold miners in French Guiana: A multicenter observational study. PLoS One. 2022 Sep 1;17(9). doi:10.1371/journal.pone.0272932

21. Grabowski MK, Mpagazi J, Kiboneka S, Ssekubugu R, Kereba JB, Nakayijja A, et al. The HIV and sexually transmitted infection syndemic following mass scale-up of combination HIV interventions in two communities in southern Uganda: a population-based cross-sectional study. Lancet Glob Health. 2022 Dec 1;10(12):e1825–34. doi:10.1016/S2214-109X(22)00424-7

22. Ntawuyamara E, Manirakiza A, Nduwimana F, Iradukunda A, Nyandwi R, Nsanzabagenzi D. Transfusion transmitted infections among blood donors of Kamenge Teaching Hospital blood bank in Burundi. Afr Health Sci. 2024 Apr 1;24(1):94–103. doi:10.4314/has.v24i1.12