Ocular syphilis among HIV-infected individuals

Syphilitic scleritis and episcleritis: A review

Scleritis and episcleritis are rare, but potentially sight-threatening forms of syphilis. To provide a full description of this neglected subset of ocular syphilis, we evaluated the English literature for reports of syphilitic scleritis and episcleritis, recording the demographics, clinical characteristics, serological data, management practices, treatment responses, and visual outcomes. Previously published descriptions of 44 patients with syphilitic scleritis (50 eyes) and 9 patients with syphilitic episcleritis (14 eyes) were identified. The predominant type of scleritis was anterior scleritis, accounting for 92.9% of cases, with nodular anterior scleritis being the most frequent subtype at 58.1%. Almost one-quarter of patients were co-infected with human immunodeficiency virus (HIV). Initial misdiagnosis was common and led to delays in initiating treatment with appropriate antibiotics. Visual outcomes were often good in both scleritis and episcleritis, irrespective of HIV infection status, although complications including scleral thinning, keratitis, and uveitis, along with permanent visual loss and an association with neurosyphilis, were reported. Response to antibiotic treatment was typically rapid, often within 1 week. With the rising global incidence of syphilis, testing patients with scleritis or episcleritis for this infectious disease is important to ensure prompt diagnosis and treatment for best ocular and systemic outcomes.

A Case of Ocular Syphilis in an HIV-Positive Patient With Penicillin Allergy

Ocular syphilis has a wide range of presentations; however, the most common findings are ophthalmalgia, blurry vision, and erythematous conjunctiva. This report presents a case of ocular syphilis in a human immunodeficiency virus-positive patient with an allergy to penicillin. On presentation, the patient was diagnosed using a fluorescent treponemal antibody absorption test, in addition to rapid plasma reagin. In this case, the patient received alternative treatment with doxycycline prior to penicillin desensitization, with marked improvement of his symptoms.

Neurosyphilis

PURPOSE OF REVIEW

This article focuses on the epidemiology, clinical presentation, diagnosis, and management of neurosyphilis, with an emphasis on clinically relevant issues faced by the practicing neurologist.

RECENT FINDINGS

The incidence of primary and secondary syphilis, the sexually transmissible stages of infection, has been on the rise for the past 2 decades. A concerning recent trend is the surge in cases of syphilis in women and of congenital syphilis. Neurosyphilis remains a relatively common complication that can occur at any stage of syphilis. Along with meningitis, meningovascular syphilis, which has been historically described as a late presentation of neurosyphilis, now frequently occurs as a manifestation of early infection. Late forms of neurosyphilis, including tabes dorsalis and general paresis, are less prevalent in the era of widespread penicillin use. As more laboratories adopt the reverse-sequence algorithm for syphilis testing, patients with serodiscordant results (ie, a reactive serum treponemal test with a nonreactive nontreponemal test) may present an increasingly encountered diagnostic challenge for neurologists. Although the CSF Venereal Disease Research Laboratory (VDRL) remains a mainstay of diagnostic testing for neurosyphilis, using a higher titer cutoff (greater than 1:320) for the Treponema pallidum particle agglutination assay (TPPA) from the CSF may improve the utility of the TPPA as a supporting criterion for the diagnosis of neurosyphilis. Penicillin G is the treatment of choice for neurosyphilis, although ceftriaxone may be a reasonable alternative therapy.

SUMMARY

A high index of suspicion and awareness of the variable clinical presentations of neurosyphilis are essential to the approach to this treatable infection. Neurologists should be mindful of the limitations of serologic testing in the diagnosis of neurosyphilis and exercise clinical judgment to determine the likelihood of the diagnosis.

Ocular syphilis

Multiple studies around the world suggest that syphilis is re-emerging. Ocular syphilis - with a wide range of presentations, most of which are subtypes of uveitis - has become an increasingly common cause of ocular inflammation over the past 20 years. Its rising incidence, diagnostic complexity, and manifestations that have only recently been characterized make ocular syphilis relevant from the public health, clinical, and scientific perspectives. We review the demographics, epidemiology, clinical features, ocular imaging findings, diagnosis, and medical management of this condition.

A case series with literature review on adjunctive usage of intravitreal ceftazidime in ocular syphilis with human immunodeficiency virus infection

BACKGROUND

Penicillin is the conventional treatment for all stages of syphilis, including ocular and neurosyphilis, according to the recommendations by the Centre for Disease Control and Prevention Sexually Transmitted Disease. This case series highlighted three cases of ocular syphilis which showed prompt treatment response as early as 24 h after the adjunctive intravitreal ceftazidime injection.

METHODS

Case Series.

RESULTS

In case 1, there was significant improvement in the vision and vitritis after 24 h of a single intravitreal ceftazidime injection. In case 2, the patient achieved his best vision after a total of three intravitreal injections in his left eye and one in his right eye. In case 3, there was a further resolution of perivascular sheathing and retinal haemorrhages seen 1 week after a single intravitreal ceftazidime injection.

CONCLUSION

The efficacy of intravitreal ceftazidime injection as a local adjunctive therapy in ocular syphilis treatment is noteworthy. It can be considered in cases which show suboptimal or slower treatment response despite early commencement of systemic penicillin to prevent devastating ocular sequelae.

Human Immunodeficiency Virus Seropositivity and Early Syphilis Stage Associated With Ocular Syphilis Diagnosis: A Case-control Study in British Columbia, Canada, 2010-2018

BACKGROUND

The incidence of syphilis has been increasing worldwide in the last 20 years, disproportionately impacting those living with human immunodeficiency virus (HIV). Alongside this increase, several jurisdictions have reported increasing incidences of syphilis-related complications, including ocular syphilis. We sought to characterize ocular syphilis cases in British Columbia (BC), Canada.

METHODS

This case-control study compared ocular syphilis cases, matched (1:4) to syphilis controls, that were diagnosed in BC between January 2010 and December 2018. Multivariable logistic regression was used to identify potential correlates of ocular syphilis, where variables were included in the final model if significant (P ≤ .05).

RESULTS

During the study period, there were 6716 syphilis diagnoses, including 66 (0.98%) ocular syphilis cases. The median age of cases was 49.5 years (interquartile range 39-59). Most (87.8%) patients were male, where 54.6% identified as men who have sex with men. The most common ophthalmologic diagnosis was panuveitis (42.4%). Of ocular syphilis patients, 48.5% were living with HIV at the time of their syphilis diagnosis, compared to 26.4% of controls (P = .001). The proportion of syphilis cases with ocular syphilis increased from 0.48% in 2010 to 0.83% in 2018. The final multivariable model demonstrated correlates between ocular syphilis and early syphilis stage, including primary/secondary (odds ratio [OR] 4.96, 95% confidence interval [CI] 1.86-13.24) and early latent (OR 4.29, 95% CI 1.62-11.34) stages, and HIV serostatus (OR 2.16, 95% CI 1.14-4.09).

CONCLUSIONS

Ocular syphilis increased over the study period, both in absolute numbers and as a proportion of all syphilis cases, a finding consistent with other jurisdictions. These findings highlight the importance of vigilance for ocular syphilis, to avoid diagnostic and treatment delays.

Management of Intraocular Infections in HIV

Purpose: Overview of treatment options for the most common intraocular opportunistic infections in patients with acquired immunodeficiency syndrome (AIDS), including ocular syphilis, ocular tuberculosis, toxoplasmic chorioretinitis, and viral retinitis. Method: Narrative Review. Results: Despite the huge advances in the development of combined antiretroviral therapy (cART) for the management of patients with human immunodeficiency virus (HIV) infection, opportunistic infections still represent a significant diagnostic dilemma and cause of ocular morbidity in patients with HIV. Conclusion: Although the treatment of intraocular infections in patients with AIDS may be challenging, prompt assessment of the clinical features and appropriate aggressive management of the underlying etiology are critical to avoid life and vision threatening.

Ocular Syphilis and Human Immunodeficiency Virus Coinfection Among Syphilis Patients in North Carolina, 2014-2016

BACKGROUND

Ocular syphilis (OS) has been associated with human immunodeficiency virus (HIV) coinfection previously. We compared demographic and clinical characteristics of syphilis patients with and without HIV to identify risk factors for developing OS.

METHODS

We reviewed all syphilis cases (early and late) reported to the North Carolina Division of Public Health during 2014 to 2016 and categorized HIV status (positive, negative, unknown) and OS status based on report of ocular symptoms with no other defined etiology. We estimated prevalence ratios (PR) and 95% confidence intervals (CI) for OS by HIV status. Among syphilis patients with HIV, we compared viral loads and CD4 cell counts by OS status. We compared symptom resolution by HIV status for a subset of OS patients.

RESULTS

Among 7123 confirmed syphilis cases, 2846 (39.9%) were living with HIV, 109 (1.5%) had OS, and 59 (0.8%) had both. Ocular syphilis was more prevalent in syphilis patients with HIV compared to HIV-negative/unknown-status patients (PR, 1.8; 95% CI, 1.2-2.6). Compared with other patients with HIV, the prevalence of OS was higher in patients with viral loads greater than 200 copies/mL (1.7; 1.0-2.8) and in patients with a CD4 count of 200 cells/mL or less (PR, 2.3; 95% CI, 1.3-4.2). Among 11 patients with severe OS, 9 (81.8%) were HIV-positive. Among 39 interviewed OS patients, OS symptom resolution was similar for HIV-positive (70.0%) and HIV-negative/unknown-status (68.4%) patients.

CONCLUSIONS

Syphilis patients with HIV were nearly twice as likely to report OS symptoms as were patients without documented HIV. Human immunodeficiency virus-related immunodeficiency possibly increases the risk of OS development in co-infected patients.

Ocular syphilis in an immunocompetent host

Syphilis is an old disease that experienced a resurgence with the emergence of HIV/AIDS. Syphilis is a reportable infection that is monitored by the Centers for disease Control (CDC) in the U.S. and rates have been rising since 2000. Although ocular syphilis is a well known consequence of syphilis infection it continues to be less frequently diagnosed, partially because ocular manifestations are not reportable to CDC. While the majority of recent cases in the U.S. have been reported in men who have sex with men (MSM) population, 50 % of these cases are HIV negative. We present a case of acute iridocyclitis and ocular hypertension due to syphilis infection. This case reiterates the need to increase healthcare workers' awareness of the importance of timely recognition of potential ocular syphilis to prevent visual sequelae from the infection. Ocular syphilis should be kept in the differential diagnosis in immunocompetent/HIV negative patients, and the importance of obtaining a detailed sexual history should not be forgotten.

The ghost of the great imitator: prognostic factors for poor outcome in syphilitic uveitis

BACKGROUND

Syphilitic uveitis is reemerging globally, may lead to any type of intraocular inflammation, and is potentially sight-threatening. We aim to characterize clinical features and prognostic factors in patients with syphilitic posterior uveitis.

METHODS

Retrospective chart review at two tertiary university-based referral centers in Brazil. Clinical data, laboratory results, and treatment outcomes were analyzed. Statistical analysis was performed using Fisher's exact test for categorical variables and Mann-Whitney U test for continuous variables.

RESULTS

Forty-four patients (81 eyes) were consecutively diagnosed with syphilitic posterior uveitis between March 2011 and April 2013.Thirty-one were male (70.5%) and the mean age was 43.8 years (range 15-81). HIV confection was disclosed in 12 patients (29.3%). The most prevalent finding was vitritis (85.2%), followed by retinal involvement (76.4%) and optic disc abnormalities (63.5%). After treatment, mean visual acuity improved from 1.2 (20/320) to 0.6 (20/80; median 20/30), but 19 eyes (23.5%) persisted with ≤ 1.0 (20/200). Factors associated with final visual acuity ≤ 1.0 despite therapy were prior use of systemic corticosteroids (p = 0.001), higher Venereal Disease Research Laboratory titers (p = 0.004), longer duration of symptoms (p = 0.024), and worse initial VA (p < 0.001).

CONCLUSIONS

Syphilitic uveitis is reemerging. Delayed diagnosis and inadvertent use of systemic corticosteroids are potentially modifiable prognostic factors to be considered for possibly improving outcomes.

Clinical Manifestations and Cerebrospinal Fluid Status in Ocular Syphilis

PURPOSE

To review the clinical manifestations, cerebrospinal fluid findings and outcomes of patients diagnosed with ocular syphilis.

METHODS

Retrospective case review of all patients treated with ocular syphilis at Groote Schuur Hospital in Cape Town, South Africa between January 2008 and January 2013.

RESULTS

A total of 77 eyes of 49 patients were included. Panuveitis was the most common presenting sign (48.9%). A lumbar puncture was performed on 37 patients (75.5%) and 64.8% (24/37) of samples had positive treponemal testing (CSF-FTA) while 24.3% (9/37) had positive non-treponemal testing (CSF-VDRL). Elevated CSF lymphocyte cell count was a strong predictor of neurosyphilis (p = 0.06 for CSF-FTA positive samples and p = 0.03 for CSF-VDRL positive samples).

CONCLUSION

The majority of patients (64.8%) who underwent lumbar puncture had cerebrospinal fluid findings suggestive of neurosyphilis. Elevated CSF lymphocyte cell count and total protein count are highly suggestive of neurosyphilis.

Increases in Ocular Syphilis-North Carolina, 2014-2015

Background

Ocular syphilis is an inflammatory eye disease due to Treponema pallidum infection. In the United States, syphilis rates have increased since 2000; clusters of ocular syphilis were reported in 2015. We investigated ocular syphilis in North Carolina to describe the epidemiology and clinical course of disease.

Methods

We reviewed syphilis cases reported to North Carolina during 2014-2015 and abstracted information from health department interviews for cases with ocular symptoms and no other defined etiology. To assess duration and severity of ocular symptoms, we also reviewed medical records and conducted structured interviews. We compared the prevalence of ocular manifestations among reported syphilis cases by demographic and clinical characteristics.

Results

Among 4232 syphilis patients, 63 (1.5%) had ocular syphilis: 21 in 2014 and 42 in 2015, a 100% increase. Total syphilis cases increased 35% through 2015. No patient with ocular syphilis named another ocular syphilis patient as a sex partner. Patients presented in all syphilis stages; 24 (38%) were diagnosed in primary or secondary syphilis. Ocular manifestations were more prevalent among syphilis patients who were male, aged ≥40 years, white, and infected with human immunodeficiency virus. No risk behaviors were associated with ocular syphilis. Among 39 interviewed patients, 34 (87%) reported reduced vision during infection; 12 (31%) reported residual visual symptoms posttreatment.

Conclusions

In North Carolina, ocular syphilis increased from 2014 to 2015 and may be due to increased recognition of ocular manifestations, or a true increase in ocular syphilis. Many ocular syphilis patients experienced vision loss; however, most improved posttreatment.

Other central nervous system infections: cytomegalovirus, Mycobacterium tuberculosis, and Treponema pallidum

Human immunodeficiency virus (HIV)-infected individuals are particularly susceptible to several central nervous system infections: human cytomegalovirus, which may cause encephalitis, ventriculitis, polyradiculitis, or polyradiculomyelitis; Mycobacterium tuberculosis, which can cause meningitis or space-occupying lesions; and Treponema pallidum subspecies pallidum (T. pallidum), which affects the meninges, cerebrospinal fluid, cranial nerves, and vasculature in early neurosyphilis, and additionally the brain and spinal cord parenchyma in late neurosyphilis. Central nervous system cytomegalovirus infection is seen in HIV-infected individuals with very advanced immunosuppression. Its prognosis is poor and optimal therapy has not been determined. Tuberculous meningitis has a high mortality in those also infected with HIV, especially in the developing world, and better therapies are urgently needed. As the rates of syphilis increase in the developed world, neurosyphilis and in particular ocular syphilis are increasingly reported. The likelihood of all three of these central nervous system infections is decreased in individuals who receive potent antiretroviral therapy.

Clinical Features and Treatments of Syphilitic Uveitis: A Systematic Review and Meta-Analysis

PURPOSE

To investigate the clinical features and efficacies of treatments for syphilitic uveitis.

METHODS

PubMed was searched for studies of syphilitic uveitis published between January 1990 and October 2016. The clinical features were summarized and appraised. The pooled success rate was defined as an improved or maintained final visual acuity and was calculated with 95% confidence intervals (CIs). Heterogeneity, subgroup analysis, sensitivity analysis, and publication bias were assessed.

RESULTS

Thirty-two studies involving 670 patients were analyzed. The most common type of syphilitic uveitis was papillitis. The pooled success rate was 0.91 (95% CI 0.84-0.97) for antibacterial agents alone (15 studies, 286 patients); 0.95 (95% CI 0.91-0.98) for antibacterial agents and systemic corticosteroids combined (11 studies, 245 patients); and 0.91 (95% CI 0.80-0.98) for antibacterial agents, systemic corticosteroids, and other immunosuppressants combined (3 studies, 73 patients). Subgroup analyses revealed no correlations of the efficacy of antibacterial agent monotherapy with study characteristics, such as human immunodeficiency virus coinfection status.

CONCLUSIONS

This systematic review and meta-analysis revealed the efficacy of antibacterial agents for treating syphilitic uveitis. Coadministration of systemic corticosteroids or immunosuppressants did not elicit further improvements in the clinical outcomes of antibacterial agents.

Use of Lumbar Punctures in the Management of Ocular Syphilis

PURPOSE

Ocular syphilis has become rare in the developed world, but is a common presentation to ophthalmology departments in South Africa. We investigated the proportion of patients diagnosed with ocular syphilis who went on to receive lumbar punctures, and determined the fraction of these who had cerebrospinal fluid findings suggestive of neurosyphilis. We aimed to determine whether the use of lumbar punctures in ocular syphilis patients was beneficial in picking up cases of neurosyphilis.

METHODS

Retrospective study of case notes of patients admitted to two district hospitals in Durban, South Africa, with ocular syphilis over a 20-month period.

RESULTS

A total of 31 of 68 ocular syphilis patients underwent lumbar puncture, and of these, eight (25.8%) had findings suggestive of neurosyphilis.

CONCLUSIONS

Lumbar puncture in ocular syphilis patients should continue to be a routine part of the investigation of these patients; a large proportion of ocular syphilis patients show cerebrospinal fluid findings suggestive of neurosyphilis, are at risk of the complications of neurosyphilis, and should be managed accordingly.

Non-human Immunodeficiency Virus-related Ocular Syphilis in a Korean Population: Clinical Manifestations and Treatment Outcomes

Purpose

To describe the clinical manifestations and treatment outcomes of ocular syphilis in patients without human immunodeficiency virus (HIV) infection.

Methods

A total of 45 eyes from 39 patients with ocular syphilis confirmed by serologic tests were reviewed retrospectively. The included cases were all non-HIV-infected patients presenting with intraocular inflammation from 2002 to 2014 at Kyung Hee University Hospital. Medical records of 45 eyes were analyzed and included best-corrected visual acuity and ophthalmologic examination findings of the anterior and posterior segments to determine the focus of inflammation. Optical coherence tomography and fluorescein angiography findings as well as both medical and surgical management were also analyzed.

Results

The mean patient age was 61.0 years (range, 37 to 89 years). Bilateral ocular involvement occurred in 6 patients (15.4%), and diagnoses at presentation were most frequently related to posterior uveitis (38%), followed by panuveitis (29%) and optic neuritis (11%). Isolated interstitial keratitis and intermediate uveitis were uncommon (4%, both). Twenty-eight eyes (62.2%) were treated with penicillin, and 11 eyes (24.4%) underwent surgical treatment. The mean baseline best corrected visual acuity was 0.79 ± 0.59 (mean ± standard deviation, logarithm of the minimum angle of resolution) and significantly improved to 0.60 ± 0.63 at the final follow-up after treatment (p = 0.019). Mean visual improvement was significantly greater in the penicillin-treated group (p = 0.001). Visual impairment at the final visit occurred in 11 eyes (24.4%). Among the visual impairment group, 10 eyes (90.1%) had posterior segment-involving uveitis.

Conclusions

Visual outcomes of treated, non-HIV-related ocular syphilis were favorable regardless of time to presentation. Posterior segment-involving uveitis at presentation was associated with poor visual outcome.

Neurosyphilis and ophthalmic syphilis in persons with negative rapid plasma reagin and positive treponemal antibody test results

The detection of serodiscordant syphilis test results raises several important clinical and public health questions. Based on our retrospective review, the probability of neurosyphilis in persons with serodiscordant serologies is low. The probability of ophthalmic syphilis may be higher, but we lack objective measures for that diagnosis.

Neurosyphilis initially presenting as hemorrhagic exudative optic neuropathy in an immunocompetent patient

We describe an unusual case of hemorrhagic exudative optic neuropathy as an initial presentation of neurosyphilis in an immunocompetent patient. The clinicians have to be alert to consider a diagnosis of syphilitic optic neuropathy in cases with hemorrhagic exudative optic neuropathy.

Prognosis of ocular syphilis in patients infected with HIV in the antiretroviral therapy era

OBJECTIVE

To describe the clinical course and prognosis of ocular syphilis in patients infected with HIV-1 in the antiretroviral therapy (ART) era.

METHODS

We conducted a single-centre retrospective chart review of ocular syphilis in patients infected with HIV-1 diagnosed between August 1997 and July 2015. The prognosis of best-corrected visual acuity (BCVA) was analysed.

RESULTS

The study subjects were 30 eyes of 20 men who had sex with men (MSM) (median age, 41). Loss of vision and posterior uveitis were the most common ocular clinical features (43%) and location of inflammation at presentation (50%), respectively. The median baseline BCVA was 0.4 (IQR 0.2-1.2), including three eyes with hand motion. BCVA≤0.4 at diagnosis was significantly associated with posterior uveitis or panuveitis (p=0.044). Seventy-five per cent were treated with intravenous benzylpenicillin and 53% were diagnosed with neurosyphilis. After treatment (median follow-up: 21 months), BCVA improved in 89% of the eyes, including all eyes with hand motion, to a median BCVA of 1.2 (IQR 0.8-1.2). Kaplan-Meier analysis showed that >28 days of ocular symptoms before diagnosis was the only factor associated with poor prognosis of BCVA. Three patients (15%) developed recurrence after treatment.

CONCLUSIONS

The prognosis of BCVA in HIV-infected patients with ocular syphilis in the ART era was favourable after proper treatment. Having >28 days of ocular symptoms before diagnosis was associated with poor prognosis. Changes in visual acuity in HIV-infected MSM should prompt an immediate assessment for ocular syphilis as delays in diagnosis and therapy can lead to irreversible visual loss.

Clinical features and incidence rates of ocular complications in patients with ocular syphilis

PURPOSE

To describe the clinical outcomes of ocular syphilis.

DESIGN

Retrospective chart review.

METHODS

The charts of patients with ocular syphilis (regardless of human immunodeficiency virus [HIV] status) seen in a uveitis referral center between 1984 and 2014 were reviewed.

RESULTS

The study included 35 patients (61 eyes). Panuveitis was the most common type of ocular inflammation (28 eyes), independent of HIV status. Thirty-three of 35 patients received systemic antibiotics with 24 patients treated with intravenous (IV) penicillin only. When compared to the HIV-positive patients, HIV-negative patients with ocular syphilis were older (P < .001), were more likely to be female (P = .004), and had poorer visual acuity at presentation (P = .01). During follow-up, the incidence rates of visual impairment were 0.29 per eye-year (EY; 95% confidence interval [CI]: 0.06/EY-0.86/EY) and 0.12/EY (95% CI: 0.01/EY-0.42/EY) among the HIV-negative and the HIV-positive patients, respectively. The incidence of blindness was 0.07/EY (95% CI: 0.009/EY-0.27/EY) and 0.06/EY (95% CI: 0.002/EY-0.35/EY) among the HIV-negative and the HIV-positive patients, respectively. Longer duration of uveitis prior to diagnosis and chorioretinitis in the macula at presentation were associated with ≥ 2 Snellen lines of visual loss (P < .01) and visual acuity loss to 20/50 or worse (P = .03) in HIV-negative patients, respectively.

CONCLUSIONS

Syphilis is an uncommon cause of ocular inflammation in both HIV-negative and HIV-positive patients. Visual loss and ocular complications were common among HIV-negative patients even with systemic antibiotic treatment. Delay of diagnosis and chorioretinitis in the macula were associated with visual loss in these patients.

Chancre of the eyelid as manifestation of primary syphilis, and precocious chorioretinitis and uveitis in an HIV-infected patient: a case report

BACKGROUND

Ocular syphilis is often difficult to diagnose because of the wide variation in clinical features.HIV co-infection may further complicate the picture.

CASE PRESENTATION

Herein the authors report an unusual primary syphilitic ocular lesion in a 45-year-old Italian HIV-infected bisexual man who presented with a unilateral eyelid lesion. Associated precocious signs and symptoms in the posterior segment of both eyes, bilateral chorioretinitis and uveitis, are described. Intravenous penicillin and steroid treatment produced a rapid improvement in clinical status and complete resolution.

CONCLUSIONS

Careful questioning about sexual behavior is crucial for unmasking unusual features of ocular syphilis in HIV-infected subjects.