Syphilis and human immunodeficiency virus (HIV)-1 coinfection: influence on CD4 T-cell count, HIV-1 viral load, and treatment response

Sex Transm Dis. 2006 Mar;33(3):143-8. doi: 10.1097/01.olq.0000187262.56820.c0.


Objectives: To assess the effect of human immunodeficiency virus (HIV)-1 and syphilis coinfection on HIV-ribonucleic acid (RNA) viral load, CD4 cell count, and the response in rapid plasmin reagin (RPR) to treatment of the syphilis infection.

Study design: Cases of syphilis diagnosed during 1 year in HIV-infected patients in Copenhagen were included. HIV-RNA, CD4 cell counts, and RPR-serology were measured before, during, and after syphilis.

Results: Forty-one patients were included. CD4 cell count decreased significantly during infection in patients with primary and secondary stages of syphilis (mean 106 cells/mm, P = 0.03). Treatment of syphilis was associated with an increase in the CD4 cell count and a decrease in HIV-RNA in the overall group (mean 66 cells/mm and -0.261 RNA log10 copies/ml, P = 0.02 and 0.04). The serological response rates for 15 patients treated with penicillin and 25 treated with doxycycline were the same.

Conclusion: Syphilis was associated with a decrease in CD4 cell counts and an increase in HIV-RNA levels that both improved after treatment of syphilis.

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Anti-Bacterial Agents / therapeutic use*
  • Anti-HIV Agents / therapeutic use
  • CD4 Lymphocyte Count
  • Denmark / epidemiology
  • Doxycycline / therapeutic use
  • Female
  • HIV Infections / complications*
  • HIV Infections / drug therapy
  • HIV Infections / epidemiology
  • HIV Infections / immunology
  • HIV Infections / virology
  • HIV-1 / physiology
  • Humans
  • Male
  • Middle Aged
  • Penicillins / therapeutic use
  • RNA, Viral / blood
  • Reagins / blood
  • Syphilis / complications*
  • Syphilis / drug therapy*
  • Syphilis / epidemiology
  • Syphilis / microbiology
  • Treatment Outcome
  • Viral Load*


  • Anti-Bacterial Agents
  • Anti-HIV Agents
  • Penicillins
  • RNA, Viral
  • Reagins
  • Doxycycline