How can syphilis cause an aneurysm?

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Scanning electron micrograph of Treponema pallidum, the spirochete bacterium that is the causative agent of syphilis. — syphilis Scanning electron micrograph of *Treponema pallidum*, the spirochete bacterium that is the causative agent of syphilis.

In the late, or tertiary, stage of syphilis, the infection can lead to the formation of an aneurysm through its impact on the aorta.

When the causative microorganism, Treponema pallidum, attacks the aorta, it destroys the vessel's elastic tissue. This loss of elasticity causes the wall of the aorta to weaken and dilate, resulting in a localized thinning and swelling known as an aneurysm. These aneurysms can grow quite large, potentially interfering with blood flow to aortic tributaries, causing pain, and risking a life-threatening rupture.12

It is important to note that such late-stage complications are largely preventable. Early detection and effective treatment with penicillin can successfully stop the progression of the disease and avoid these severe cardiovascular outcomes.2