Over the past decade, rates of syphilis have soared in Canada and other high-income countries. Syphilis outbreaks are common and ongoing among men who have sex with men (MSM). In the United States and possibly elsewhere, rates of syphilis among MSM are so high that some researchers refer to it as an epidemic within this community.

Syphilis is the name given to an infection caused by the germ T. pallidum. This disease can be spread in the following ways:

  • kissing
  • anal, oral or vaginal sexual contact
  • sharing needles and other equipment for substance use
  • from an infected mother to child during pregnancy or birth

The germs that cause syphilis (called treponemes) can cause sores on the genitals, rectum and mouth. These sores can be an entry point for HIV and other sexually transmitted infections (STIs) to get inside the body. Once inside the body, treponemes can enter the lymphatic system or the bloodstream -- just like HIV. From there, in a matter of hours or a few days, treponemes can quickly spread throughout the body and reach the brain, heart and other vital organ-systems.

Initial symptoms of syphilis, particularly if sores or lesions are inside the genitals or rectum, may go unnoticed, so regular medical checkups and laboratory testing for syphilis and other germs are vital for sexually active people.

Researchers in the Netherlands have been conducting blood tests on more than 1,000 mostly HIV positive MSM, screening them for syphilis. They have found that a substantial proportion had symptom-free syphilis, detected only with blood tests. Based on their results, researchers are calling for more frequent syphilis testing in HIV positive MSM.

Study Details

Researchers at the Academic Medical Centre at the University of Amsterdam took some steps to try to understand the trends in syphilis:

  • First, they reviewed medical records at their clinic between 1994 and 2003, looking at changes in syphilis cases over time.
  • Second, they assessed syphilis cases between March 2003 and June 2003, and then retested these patients between September 2003 and December 2003.


In their clinic, which had more than 1,000 HIV positive MSM patients, researchers found the following trends:

  • 1994 to 1997: one case of syphilis
  • 1997 to 2000: three cases of syphilis
  • Jan 2000 to June 2003: 77 cases of syphilis
  • September 2003 to December 2003: 17 cases of syphilis

These findings suggest a massive increase in syphilis cases over the 10 years of the study. Although the researchers are not ready to release data from syphilis testing in more recent years, they did mention that presently blood tests continue to show very high rates of syphilis. What's more, about 31% of syphilis cases were detected only with blood tests because patients did not have symptoms.

The Dutch doctors pinpoint the following circumstances to help explain the surge in syphilis rates:

  • The use of highly active antiretroviral therapy (HAART) has greatly improved survival and quality of life in HIV positive people.
  • With a return to health, interest in sex has resumed.
  • Many HIV positive people are probably choosing other HIV positive people as sex partners so that unprotected intercourse can occur.
  • Yet unprotected sex appears to have greatly increased the risk of these men getting syphilis.

Not Just in the Netherlands

Researchers at the UCLA Medical Centre in Los Angeles have also found high rates of symptom-free STIs among MSM, a finding that suggests this problem may be occurring in sexual networks worldwide.

What to Do?

Commenting on the Dutch findings, Dr. Jeffery Klausner, the director of STD Prevention and Control at the San Francisco Department of Public Health, issued the following guidance in the February 2009 issue of the journal Sexually Transmitted Diseases:

"I recommend that clinicians obtain a syphilis screening test in HIV-infected patients with every CD4+ T cell count or plasma HIV viral load. In clinical practice, these measures are often done every three or four months."


  1. Golden MR, Marra CM, Holmes KK. Update on syphilis: resurgence of an old problem. Journal of the American Medical Association. 2003 Sep 17;290(11):1510-4.
  2. Branger J, van der Meer JT, van Ketel RJ, et al. High incidence of asymptomatic syphilis in HIV-infected MSM justifies routine screening. Sexually Transmitted Diseases. 2009 Feb;36(2):84-5.
  3. Klausner JD. Frequency of syphilis testing in HIV-infected patients: more and more often. Sexually Transmitted Diseases. 2009 Feb;36(2):86-7.
  4. Rieg G, Lewis RJ, Miller LG, et al. Asymptomatic sexually transmitted infections in HIV-infected men who have sex with men: prevalence, incidence, predictors, and screening strategies. AIDS Patient Care and STDs. 2008 Dec;22(12):947-54.