STD Quarterly

Syphilis rate on the increase in gay, bisexual men in the U.S.

Stats show upswing in disease among men who have sex with men

Get ready to tackle a resurgence of syphilis among males who have sex with males (MSM). Results from a new study indicate that increasing syphilis cases among this population group account for most of the recent overall increase in national syphilis rates and may be a harbinger of increasing rates of HIV infection among MSM.1

In the new report, researchers assessed the epidemiology of primary and secondary syphilis in the United States and estimated the percentages of cases occurring among men who have sex with men. The researchers analyzed national syphilis surveillance data from 1990 through 2003, and they estimated numbers of cases occurring among MSM by modeling changes in the ratio of syphilis cases among men to cases among women.

What were the results? During 1990 through 2000, analysts found that the rate of primary and secondary syphilis decreased 90% overall, declining 90% among men and 89% among women. However, the overall rate increased 19% between 2000 and 2003, reflecting a 62% increase among men and a 53% decrease among women. In 2003, an estimated 62% of reported cases occurred among MSM, according to the researchers.

Why the uptick?

Many factors may contribute to the increases in syphilis among MSM, such as prevention fatigue, substance abuse, and the use of the Internet to find sex partners, says James Heffelfinger, MD, MPH, a medical epidemiologist at the Centers for Disease Control and Prevention (CDC) and lead author of the new analysis. Treatment optimism related to the availability of highly active antiretroviral therapy (HAART) also may increase risky behavior, Heffelfinger notes.

Also look to such factors as increased use of crystal methamphetamine resulting in unsafe sexual practices, says Khalil Ghanem, MD, assistant professor of medicine and associate fellowship program director in the Division of Infectious Diseases at Johns Hopkins University School of Medicine in Baltimore.

Sexual networks with high syphilis prevalence among MSM also may fuel the increase, says Ghanem. Those who have sex within those networks are likely to be exposed to the disease, he notes.

Get an overview

In 2005, syphilis cases increased for the fifth consecutive year. The disease's all-time low was registered in 2000, notes Jennifer Ruth, a CDC spokeswoman. While MSM accounted for most increases, increased vigilance also is needed when it comes to African-Americans and women, Ruth states.

In 2005, syphilis rates among blacks increased for the second consecutive year, following more than a decade of declines, states Ruth. Between 2004 and 2005, the rate among blacks per 100,000 population increased 1.4% (from 8.8 to 9.8), with the largest growth found among black men. Between 2004 and 2005, the syphilis rate among black males moved up 12.9% (from 13.9 to 15.7), while the rate among black women increased 4.8% (from 4.2 to 4.4).2

While disparities still exist, racial gaps in syphilis rates are narrowing, according to the CDC statistics. The rate of primary and secondary syphilis per 100,000 population in 2005 was 5.4 times higher among blacks than among whites; in contrast, in 1999, the comparable rate was 29 times greater between the two groups.2

While syphilis rates remain lower among women than men, keep an eye on increased infection rates among females, public health officials caution. 2005 saw the first increase among women in over a decade, Ruth states. Rates moved up 12.5% from 2004 to 2005 (from 0.8 per 100,000 population to 0.9). The growth was driven by increased rates among black women and Hispanic women (up from 0.7 in 2004 to 0.9 in 2005); rates among women in all other ethnic groups declined or remained stable, the CDC reports.2

All the news about syphilis is not so grim. Rates for congenital syphilis continue to decline, the CDC reports.2 Rates fell 12% between 2004 and 2005, as they dropped from 9.1 per 100,000 live births to eight. What is affecting the decline? CDC analysts point to reduction in syphilis rates among women in earlier years and the ongoing contribution of prenatal screening programs.2

Stop the spread

Syphilis is caused by the bacterium Treponema pallium. Infection is transmitted from person to person through direct contact with a syphilis sore. While sores occur mainly on the external genitals, vagina, anus, or in the rectum, they also can occur on the lips and in the mouth. Syphilis often has been called "the great imitator" because so many of its signs and symptoms are indistinguishable from those of other diseases. Like many other STDs, syphilis facilitates the spread of HIV; it increases transmission of the virus at least two- to fivefold.3

In May 2006, the CDC released its updated National Plan to Eliminate Syphilis to take direct aim at syphilis elimination. The plan is designed to sustain efforts in populations traditionally at risk, including women and African-Americans, and to support innovative solutions to fight the resurgence of syphilis among MSM. The CDC also has updated its Syphilis Elimination Effort (SEE) tool kit, which is designed to help public health practitioners plan, manage, and develop syphilis elimination/prevention efforts. New information has been added for reaching MSM; providers may download Screening and Testing Men who Have Sex with Men (MSM) for Syphilis — A Guide for Health Care Professionals, by going to the CDC web site,, then clicking "SEE tool kit" and "Special Focus: MSM."

The reversal in syphilis trends in recent years is a significant public health concern, and effectively reaching men who have sex with men will be critical to success, says Heffelfinger. National efforts are under way to improve monitoring of syphilis trends, better understand factors associated with the observed increases, and improve efforts to prevent syphilis transmission, according to the new analysis. "We must continue to adapt to meet the new challenges brought on by syphilis," Heffelfinger states.


  1. Heffelfinger JD, Swint EB, Berman SM, et al. Trends in primary and secondary syphilis among men who have sex with men in the United States. Am J Public Health 2007; Apr 26 [Epub ahead of print].
  2. Centers for Disease Control and Prevention. Trends in Reportable Sexually Transmitted Diseases in the United States, 2005. National Surveillance Data for Chlamydia, Gonorrhea, and Syphilis. Atlanta; December 2006.
  3. Centers for Disease Control and Prevention. HIV prevention through early detection and treatment of other sexually transmitted diseases — United States recommendations of the Advisory Committee for HIV and STD Prevention. MMWR 1998; 47(RR-12):1-24.