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Trying to stop the syphilis outbreak in British Columbia

Over the past decade, rates of syphilis have increased dramatically in high-income countries – and Canada is no exception to this trend. 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. These germs 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.

Treponemes, the germs that cause syphilis, can cause inflammation, sores or lesions on or inside the genitals, rectum and mouth. These sores can be an entry point for HIV and other sexually transmitted infections (STIs), allowing them 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, liver and other vital organ-systems. Once inside these organ-systems, treponemes attack and weaken them.

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

Focus on British Columbia

Researchers at British Columbia’s Centre for Disease Control (BCCDC) have been studying the ongoing outbreak of syphilis in that province. In the past 10 years, BC has taken a number of steps to try to reduce cases of this disease as follows:

treating large numbers of people with antibiotics;
contacting sexual partners of people with syphilis so they can be tested and treated;
Internet-based syphilis education;
focusing syphilis educational events at the gay community;
encouraging a greater awareness of the need to test and treat syphilis throughout the province.

Despite all of these steps, syphilis rates in BC are at least 10 times greater than they were a decade ago. And an increasing number of people who are diagnosed with syphilis in that province have had this disease before. To try to understand more about syphilis in BC, researchers at the BCCDC reviewed cases of syphilis that were diagnosed in the past 10 years as part of a study. Their findings are disturbing and suggest that additional resources are needed to help stem this STI epidemic.

Study details

BCCDC analysed data on a total of 1,473 people who had been diagnosed with syphilis and subsequently treated between 1995 and 2005.

Results—Reinfection

In total, 88 people (6% of the study population) had syphilis in the past and were apparently infected at least once more.

On average, there was an interval of about 15 months between the first and second diagnosis of syphilis.

Profile

In this study, statistical analysis revealed that people with the following profile were vulnerable to reinfection with syphilis:

being HIV positive;
having a history of other STIs, particularly gonorrhea and Chlamydia;
being of Aboriginal ethnicity;
being gay or bisexual.

This last finding is interesting because 74% of people in this study were neither gay nor bisexual.

A large problem

In the BCCDC study, about 6% of people who had syphilis in the past became reinfected. Data suggest that this figure rose to about 10% in 2006 (more recent information on reinfection rates are not yet publicly available). Because the study team used a conservative approach to defining syphilis reinfection, they may have underestimated the number of people with this problem.

According to the BCCDC, in 2008 overall rates of syphilis were still high but seemed to have stabilized at about 330 new cases per year. Most of these were in men between 25 and 59 years old. Among these men, about 70% were gay or bisexual. And among gay and bisexual men, about 60% of cases of syphilis in 2008 occurred in men who were HIV positive.

Focus on HIV

Some HIV positive people engage in sero-sorting—the practice of having sex with other HIV positive people. Unfortunately, in some cases of sero-sorting there is the misconception that the use of condoms is unnecessary. Syphilis may inadvertently be transmitted among HIV positive people who have unprotected sex with each other. Condoms can help reduce the risk of getting and transmitting syphilis, hepatitis C virus and other germs that can cause nasty complications.

The BCCDC team suspects that syphilis may weaken the immune system and make some people more susceptible to future infection with treponemes. Although this is a reasonable assumption, more research is needed in order to understand the long-term impact of syphilis on the immune system.

Given the high rates of apparent reinfection seen in this study, perhaps more frequent testing and more intensive treatment of syphilis in HIV positive people might be useful.

—Sean R. Hosein

REFERENCES:

Lukehart SA, Hook EW 3rd, Baker-Zander SA, et al. Invasion of the central nervous system by Treponema pallidum: implications for diagnosis and treatment. Annals of Internal Medicine 1988 Dec 1;109(11):855–862.
Tramont EC. Treponema pallidum (syphilis). In: Mandell GL, Bennett JE and Dolin R, editors. Principles and Practice of Infectious Diseases. Sixth ed. Philadelphia: Elsevier; 2005. P. 2362–2379.
Lukehart SA. Syphilis. In: Fauci AS, Braunwald E, Kasper DL, editors. Harrison’s Principles of Internal Medicine. 17th ed. McGraw-Hill Companies, Inc.; 2008. P. 956–962.
British Columbia Centre for Disease Control. British Columbia Annual Summary of Reportable Diseases. 31 July 2009. Available at: www.bccdc.ca [Accessed 14 August 2009].
British Columbia Centre for Disease Control. Annual Surveillance Report: HIV and Sexually Transmitted Infections. 2008. Available at: www.bccdc.ca [Accessed 14 August 2009].
Sullivan PS, Hamouda O, Delpech V, et al. Reemergence of the HIV epidemic among men who have sex with men in North America, Western Europe and Australia, 1996-2005. Annals of Epidemiology. 2009 Jun;19(6):423-31.
Ogilvie GS, Taylor DL, Moniruzzaman A, et al. A population-based study of infectious syphilis rediagnosis in British Columbia, 1995-2005. Clinical Infectious Diseases. 2009 Jun 1;48(11):1554-8.
Expert working group. Canadian Guidelines on Sexually Transmitted Infections. January 2008. Available at: http://www.phac-aspc.gc.ca/std-mts/sti_2006/sti_intro2006-eng.php [Accessed 14 August 2009].

Created on: 08/18/2009

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