Infectious Syphilis: The Return of an Epidemic

Robert B. Stroube, MD, MPH


May 12, 2008

In This Article

The Current Epidemic

In the current epidemic, case rates continue to climb with an increase of almost 14% from 2005 to 2006. Cases are predominantly among men with a male-to-female ratio of 5.2:1,[6] and with an increase in MSM from 4% of total cases in 2000 to 62% in 2006.[11] The increase in the male-to-female ratio has occurred in all racial and ethnic groups and in all regions. MSM at highest risk are those who are HIV-infected; those with multiple sex partners; those with anonymous sex partners; and those who use drugs, such as methamphetamine, sildenafil, and nitrate inhalants.[12,13] Gay men with syphilis are generally more affluent, older, and less likely to attend public sexually transmitted disease clinics. Many are currently getting HIV care. The largest numbers of cases of MSM with syphilis have been reported in New York, NY; Atlanta, Georgia; Ft. Lauderdale, Florida; Miami; Chicago, Illinois; Houston, Texas; Los Angeles, California; and San Francisco. The age groups with the highest rates are those between 35 and 39 years and 40 and 44 years, unlike earlier epidemics that were in younger age groups. It is postulated that the rapid geographic spread of syphilis in MSM is linked with frequent travel and with the use of the Internet to recruit sex partners.[14] Oral sex is an important risk factor for MSM. Unfortunately, many MSM perceived oral sex as a safe sex practice.[6]

The syphilis epidemic in MSM presents many different challenges from those that were used in earlier outbreaks, which focused on the poor and disenfranchised populations. The MSM population has been more difficult to reach. Social marketing campaigns have been designed to increase the recognition of the symptoms of syphilis by MSM, to improve partner notification, and to encourage more screening of persons at risk. It has been shown that the most cost-effective screening is that which is done during routine medical encounters by people at risk.[12]

The resurgence of infectious syphilis in MSM reemphasizes the need for the private physician community and the public health agencies to work closely together to control and eliminate this disease. The words of Dr. William Brown, written in 1968, are still applicable in the 21st century:

Past experience has taught us that penicillin alone is not enough. Syphilis control depends on a combination of factors including a high index of suspicion, clinical acumen, laboratory tests, diagnosis, treatment, case reporting, and epidemiology. In addition to interviewing patients for sexual contacts and follow-up by trained health department personnel, the epidemiologic (preventive) treatment of sexual contacts exposed to infectious syphilis, even though negative on initial examination, is essential to successful control.[3]

Syphilis is the great imitator, so physicians must maintain a high degree of suspicion and a basic knowledge of syphilis symptomatology, laboratory tests, and treatment. It is important to take a good sexual history from the patient to identify MSM; bisexuals; and particularly men who have sex occasionally with other men, but who don't consider themselves as gay. Do they engage in risky sexual behaviors, such as anonymous sex partners, multiple sex partners, or participation in bath houses or circuit parties? Oral sex is an important mode of transmission that is often not recognized as such by patients, and this needs to be elucidated. Do they meet sex partners over the Internet? Travel histories can be important because syphilis can be acquired in other areas.

HIV infection is a major risk factor. All patients tested for HIV should also be tested for syphilis and vice versa. Syphilis testing should be done on all high-risk patients, such as gay men; bisexual men; patients with multiple sex partners; pregnant women; persons using drugs, particularly methamphetamines and nitrate inhalers; people who trade sex for drugs or money and their customers; and all HIV patients. Pregnant women should be screened in the first and third trimesters to prevent congenital syphilis in their babies.

Diagnosis of early syphilis can be made definitively by dark field examination, available through many local health departments, or direct fluorescent antibody testing of exudates from a lesion. Serologic testing of blood is used most frequently for a presumptive diagnosis. Testing is initially done with nontreponemal antigen tests, such as the RPR (rapid plasma reagin) or VDRL (venereal disease research laboratory). Reactive tests must be confirmed by treponemal antigen tests, such as the FTA-ABS (fluorescent treponemal antibody absorbed) or the TP-PA (T pallidum particle agglutination).

It is crucial that physicians work closely with their local health departments to control infectious syphilis. Physicians should provide complete and timely reporting of positive tests and diagnosed cases to the local health departments, and they should work with them to conduct partner notification activities. Health departments have staff trained in working with case patients to identify their contacts and to facilitate the testing and treatment of them.

The recommended treatment for primary and secondary syphilis is 2.4 million units of penicillin G benzathine administered intramuscularly in a single dose. Although there are limited data, patients with penicillin allergy can be treated with 100 mg of doxycycline twice daily for 14 days or 500 mg of tetracycline 4 times daily for 14 days. It is also very important that all sexual contacts of infectious cases exposed within the past 90 days receive prophylactic treatment. More complete treatment information is available in the US Centers' for Disease Control and Prevention (CDC's) STD Treatment Guidelines-2006.[15]

A Partnership for Syphilis Control: Public Health and Private Practice Clinicians

With private physicians and public health agencies working together, syphilis can be controlled in the United States and the optimistic vision of Dr. William Brown in 1968 can be fulfilled: "With teamwork between private physicians and health officers, a lasting victory over the treponeme of syphilis, which has plagued human beings for so long a time, is inevitable.[3]"


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as: