How HIV Affects Ocular Syphilis Outcomes

The number of syphilis cases has risen steadily in the United States since 2000. Those who are at particularly elevated risk include men who have sex with men and patients infected with human immunodeficiency virus (HIV).

Caused by spirochetal bacteria (Treponema pallidum) and transmitted sexually, syphilis can infect almost any organ in the body. Once rare, ocular syphilis (considered a type of neurosyphilis that often occurs with meningitis but may stand alone) is increasing in incidence and prevalence in the United States. The problem is serious enough that the CDC issued a clinical advisory in 2015. Since then, American clinicians have reportedly diagnosed more than 200 cases.

The November 2016 issue of Current Infectious Disease Reports includes a clinical review of ocular syphilis that heightens awareness of this re-emerging condition and discusses the clinical syndrome, diagnosis, and treatment. Using 2 cases as the basis for learning, the review describes key symptoms: progressive bilateral vision loss for 3 months, floaters, and a unilateral paracentral scotoma (visual field defects).

Eye pain, vision loss, floaters, flashing lights, eye pressure, or photophobia are also common symptoms. Vision loss is permanent for about 10% of patients. Visual symptoms vary widely, and patients may have no other syphilis symptoms.

Some researchers indicate that HIV-infected patients may have worse outcomes than uninfected individuals.

The CDC recommends involving an ophthalmologist at first suspicion of ocular syphilis. Diagnosis requires ophthalmologic examination and a lumbar puncture. Careful evaluation in HIV-infected patients establishes the diagnosis and rules out any of the other opportunistic infections that affect the eye.

Review of the limited available treatments for neurosyphilis is important. Oral penicillins or oral penicillin alternatives are ineffective for ocular syphilis and should not be used. Benzathine penicillin does not cross the blood-brain barrier and also should not be used.

The preferred treatment is a 10- to 14-day regimen of either 18 million to 24 million intravenous units of aqueous crystalline penicillin per day or 2.4 million units of intramuscular procaine penicillin given with oral probenecid 500 mg 4 times daily.

Rarely, patients may develop a Jarisch Herxheimer reaction, which is an acute febrile reaction accompanied by headache, myalgias, rigors, or chills that occurs within 24 hours of the initiation of treatment for ocular syphilis.

Sexual partners should be treated and monitored for at least 6 months.