Contributor: John Dacus, MD
Last Update: 11/1/2007
Syphilis is a venereal disease caused by a spirochete, Treponema pallidum. It is an ubiquitous disease which has caused a great deal of human suffering over centuries and is today a major cause of perinatal morbidity and mortality in developing countries. Syphilis may affect numerous organs; and the renowned internist Sir William Osler is quoted as stating that if a physician understands syphilis, he understands medicine.
Syphilis is contracted mainly by sexual practices – sexual intercourse or oral genital sex. It is usually divided into 4 stages – primary, secondary, latent, and tertiary. The diagnosis is made by serology, dark field microscopy, physical examination, and lumbar puncture.
The primary treatment of syphilis continues to be penicillin. The organism has not developed resistance to this antibiotic. In the pregnant woman allergic to penicillin, the best treatment approach is desensitization to penicillin as the alternative antibiotics are either teratogenic or achieve inadequate levels in the fetus.
Serology testing in syphilis comprises anticardiolipin tests for screening using the RPR (rapid plasma reagin) or the VDRL (venereal disease research laboratory); and if positive, followed by the FTA (fluorescent Treponema antibody) absorption or the MHATP (microhemaglutination antibody Treponema pallidum) test for diagnosis. In primary syphilis the anticardiolipin tests may be negative in 20-30% of the cases, and dark field microscopy is indicated if a syphilitic chancre is suspected. In secondary, latent, and tertiary syphilis, anticardiolipin and specific Treponemal antibodies are almost always positive.
The diagnosis of primary syphilis is primarily by identification of the spirochete by dark field microscopy. A patient with a nonpainful ulcerous lesion (chancre) usually found in the genital region should be evaluated for primary syphilis by sending the patient to the Health Department. Polymerase chain reaction (PCF) has increased the sensitivity of detection in samples obtained from genital lesions.
The recommended treatment for primary syphilis is benzathine penicillin 1.2 million units intramuscularly in each buttock for a total of 2.4 million units. Only rarely does this result in the occurrence of the Jarisch-Herxheimer reaction. This can present with fever and myalgias in the woman with occasional development of uterine contractions. It is thought to be prostaglandin mediated caused by the death and destruction of the spirochetes. Tocolysis is only very rarely indicated.
The diagnosis of secondary syphilis is made by positive serology (a positive anticardiolipin test and a positive antitreponemal antibody test) and clinical manifestations. The patient may present with flu-like symptoms and lymphadenopathy and a macular-papular rash characteristically involving the palms and soles. Additional findings may include fever, alopecia, condyloma lata, meningitis, hepatitis, and mucous patches.
The recommended treatment of secondary syphilis is 1.2 million units of benzathine penicillin in each buttock. The Jarisch-Herxheimer reaction may be more frequent secondary to the spirochetemia, and the patient should be observed for 1-2 hours after the penicillin injections.
Latent syphilis is divided into early latent (less than a year’s duration) and late latent (greater than a year’s duration).
Early Latent Syphilis
Early latent syphilis is diagnosed by positive serology (both screening and antitreponemal tests are positive), and no clinical manifestations present. In addition, the patient should have a negative screening test with a year to confirm early latent syphilis.
Early latent syphilis is treated with 1.2 million units of benzathine penicillin injected into each buttock.
Late Latent Syphilis
Late latent syphilis is diagnosed by the absence of clinical findings in a patient with positive serology (both screening and antitreponemal tests are positive), and duration of disease greater than one year.
Treatment of late latent syphilis is 1.2 million units of benzathine penicillin in each buttock weekly for three weeks for a total of 7.2 million units.
Tertiary syphilis comprises syphilitic disease of the CNS, cardiovascular system or the musculoskeletal system.
Diagnosis of Neurosyphilis
Neurosyphilis – The diagnosis is made by clinical manifestations; paresis, tabes dorsalis, Argyll-Robertson pupil, gumma, Charcot’s joints, and seizures combined with lumbar puncture demonstrating a positive VDRL, increased cell count, and increased protein.
Treatment of Neurosyphilis
The treatment is intravenous penicillin G, 3-4 million units every 4 hours for 10-14 days. Some experts suggest also three weekly injections of 2.4 million units of benzathine penicillin.
Diagnosis of Cardiovascular Syphilis
The diagnosis of aortic aneurysms, aortic insufficiency, coronary stenosis, and myocarditis is made by symptoms, physical examination, EKG, ECHD, and angiography.
Treatment of Cardiovascular Syphilis
The treatment is 2.4 million units of benzathine penicillin IM for 3 doses. Therapy, including surgery, of specific manifestations by cardiologist or cardiovascular surgeon.
Musculoskeletal manifestations of tertiary syphilis may be treated with 3 weekly injections of 2.4 million units of benzathine penicillin.
Follow-up of patients treated for syphilis should be serial RPR’s or VDRL’s. With primary, secondary, and early latent syphilis, the titers should drop 4 fold by 12 months; and with late latent and tertiary syphilis, the titers should drop 4 fold by 18-24 months. Monthly RPR or VDRL during pregnancy is appropriate.
False positive VDRL or RPR (negative FTA and MH ATP tests) can be caused by viral illnesses such as hepatitis, connective tissue disorders, heroin addiction, malaria, antiphospholipid antibodies, and even pregnancy.
Indications for Lumbar Puncture
- Any stage of syphilis also infected with HIV.
- Presence of aortitis, gumma, or iritis and positive serology.
- Four fold rise of VDRL or RPR after treatment.
- Failure of 4 fold decline of VDRL or RPR following treatment.
- Presence of CNS symptoms and positive serology.
- Holmes KK, Sparling PF, et al. Sexually transmitted diseases. McGraw-Hill, 3rd edition, 1999; 473-510.
- Remington JS, Klein JO. Infectious diseases of the fetus and newborn infant. WB Saunders Co., 5th edition, 2001; 643-682.
- Syphilis. 1998 Guidelines for treatment of sexually transmitted diseases. US Dept of Health and Human Services, Center for Disease Control and Prevention, 28-48.
- Penicillin Therapy for Syphilis in Pregnancy