Ocular syphilis and early diagnosis

Pubblicato il

Tuesday, 27 February 2024

Argomento

Eye infections

Ocular syphilis is quite rare, but can have a serious impact on the visual apparatus and, above all, is extremely difficult to diagnose correctly.

Syphilis is an infection caused by the bacterium spirochete Treponema pallidum and can have severe ocular manifestations, likely to involve all structures of the eye, leading to interstitial keratitis, chorioretinitis, retinitis, retinal vasculitis and neuropathy of the cranial nerves and optic nerve. Patients with ocular syphilis are also at risk of neurosyphilis.

Syphilis is an infection transmitted mainly sexually, but also by contact with the skin and mucous membranes, or trans-placental from the mother to the unborn child.

La spirochete Treponema pallidum, First identified in 1905 by Schaudinn and Hoffman, it penetrates through the skin and mucous membranes, reaches the lymph nodes and then spreads systemically.

It is possible to distinguish a congenital (or transplacental) and an acquired form of this disease. Acquired syphilis is characterised by three clinical phases - primary, secondary and tertiary - and involves numerous organs and apparatuses.

Prior to the advent of penicillin, syphilis was associated with a high mortality and morbidity rate, but with the introduction of antibiotic therapy, coupled with changing socio-economic conditions and a reduction in risk behaviour, the incidence of syphilis declined rapidly. In recent years, however, the disease seems to have regained strength, even in the higher-income social strata. In Italy, with regard to the time trend, syphilis I-II cases remained stable until 2000, while thereafter they increased significantly. In 2005, in particular, there was a fivefold increase in diagnoses compared to 2000 and a new peak in 2016.

Ocular involvement in syphilis is rare and typically occurs in secondary or tertiary syphilis. The most frequent ocular clinical manifestation is uveitis, which occurs in 2.5-5% of patients with the tertiary form of the disease. The main signs include keratic precipitates, iritis and iridocyclitis, and inflammation may occur in both granulomatous and non-granulomatous forms. Less common are manifestations in the posterior segment, including vitritis, vasculitis, papillitis, exudative retinal detachment, uveal effusion, central retinal vein occlusion, neuroretinitis and retinal necrosis.

Furthermore, syphilis is a subtle disease as it does not manifest itself with pathognomonic signs, but with a multiplicity of signs and symptoms, making the clinical course complex, which may lead to a missed diagnosis or a delay in treatment. In syphilis, ocular involvement, and in particular at the level of the posterior segment, goes into differential diagnosis with other infectious diseases such as tuberculosis, or non-infectious diseases such as sarcoidosis, or other hereditary retinal diseases.

The above highlights the extreme importance of performing systemic, serological and radiological investigations in all cases of papilla oedema or retinal changes without apparent cause, even in patients with a silent history of known infectious diseases. The interdisciplinary collaboration between ophthalmologist, infectivologist, internist and neurologist is also crucial for the management of suspected 'masquerade conditions' such as syphilis, which has always been referred to as the 'great masquerader', since it presents itself with a variety of systemic manifestations that can cause misdiagnosis.