Ocular Syphilis: A Review

A comprehensive review of ocular Syphilis by Drs Mudit Tyagi, Khushboo Chauhan and Joveeta Joseph from LVPEI, and others, discusses the epidemiology, microbiology, clinical features, medical imaging, and treatment of syphilis, with a focus on its ocular manifestations. 

Syphilis is a bacterial infection caused by a spirochaete (shaped like a coil), Treponema pallidum. Spreading through sexual contact, syphilis has a current incidence of nearly 6 million cases every year, with Africa accounting for the highest incidence. Men who have sex with men (MSM) and female sex workers (FSWs) are at particular risk of acquiring this infection. T. pallidum is one of the smallest known human pathogens and its reduced genome makes it dependent on hosts to complete its life cycle. However, its spiral shape gives it great motility and therefore, virulence. It spreads rapidly and can even penetrate immune-privileged tissue like the central nervous system, the placenta, or the eye. 

The incidence of ocular syphilis is not fully known, with various studies pointing to an incidence of about 1%-2% among those with syphilis. HIV positive patients with syphilis seem to have a higher likelihood of developing the condition. Ocular syphilis presents primarily as uveitis (an inflammation in the eye) and is easy to misdiagnose. Apart from systemic and ocular syphilis, the infection can also present as neurosyphilis, with detectable infection of the cerebrospinal fluid, and congenital syphilis where it passes to the child at birth. 

A new paper in the Ocular Immunology and Inflammation journal by Drs Khushboo Chauhan, Mudit Tyagi and others presents a major review of syphilis with a focus on ocular syphilis. The review discusses the clinical features, microbiology, immune response, and treatment of a treponemal infection. Along with these details, the review notes the presentation of ocular syphilis in various anterior and posterior ocular tissue. The paper underscores the importance of using ocular imaging to diagnose ocular syphilis-noting the risks of misdiagnosis as the condition mimics other chronic inflammatory conditions.  

Serological tests, treponemal and non-treponemal, are used to diagnose an infection in the laboratory. These tests look at identifying specific antibodies against T. pallidum in the serum, or to monitor disease activity and treatment response. Once identified, the paper notes the remarkable  success of penicillin in treating all types of treponemal infection, including ocular syphilis. It also notes the success of other antibiotics, along with systemic and ocular corticosteroids in fighting back inflammation. By bringing together the challenges of diagnosis, its ability to mimic other inflammatory conditions, and noting treatment options, this paper offers a comprehensive review of the current state of affairs in managing this condition. 

‘Ocular Syphilis is a great masquerade and can mimic any of the uveitic conditions. The incidence of Syphilis is showing a resurge and it becomes important for clinicians to be aware of this disease,’ says Dr Mudit Tyagi, Head, Smt Kanuri Santhamma Centre for Vitreo-Retinal Diseases, and the corresponding author for this review. 

Chauhan K, Fonollosa A, Giralt L, Artaraz J, Randerson EL, Goldstein DA, Furtado JM, Smith JR, Sudharshan S, Ahmed AS, Nair N, Joseph J, Pavesio C, Westcott M, Trepatchayakorn S, Sallam AB, Elhusseiny AM, Tyagi M. Demystifying Ocular Syphilis - A Major Review. Ocul Immunol Inflamm. 2023 Jun 12:1-15. doi: 10.1080/09273948.2023.2217246. Epub ahead of print. PMID: 37307579.  

Image credit: Syphilis Bacteria; NIH Photo library; CC BY 2.0. 

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