Schistosomiasis

Schistosomiasis is an infection caused by trematode worms of the genus Schistosoma, including Schistosoma haematobium, endemic in sub-Saharan Africa and Middle East, Schistosoma mansoni endemic in sub-Saharan Africa, South America and Caribbeans and Schistosoma japonicum, endemic in People’s Republic of China, the Philippines and Indonesia. It affects 250 million people worldwide, 201.5 million in Africa.

Infection in humans occurs through contact with fresh water infested by free-swimming cercariae, released by intermediate host snails, which penetrate intact skin and gain access to venous and lymphatic vessels. After an acute stage, disease can progress to chronic clinical manifestations in which adults lay eggs in blood vessels, which are released in intestinal lumen or into the bladder cavity and in the environment though stool or urine. Occasionally, eggs can remain trapped in the surrounding tissue, leading to granuloma formation and organ damage at entrapment sites. Among the clinical scenarios, hepato-intestinal schistosomiasis and urogenital tract are the most frequently reported. Among the ectopic sites of oviposition, cardiovascular and cerebrovascular involvement was described in previous cases and case series in literature. Several pathophysiological mechanisms could explain vascular lesions in patients with schistosomiasis, including the direct arterial wall damage due to obliterative endarteritis involving vasa vasorum, lesions due to contiguity with a focus of inflammation in surrounding tissues or to vasculitis process, as described in aneurysms or pathology of intra- and extracranial carotid arteries, potentially leading to arterial rupture or stroke. Among the specific features to be considered when managing arterial lesion in patients with schistosomiasis are the earlier age at diagnosis compared to classic atherosclerotic damage, the usually impaired general conditions of the patient, due to factors as hemodynamic issues or malnutrition, the histology changes reported in the vessels walls that predispose to rupture and the parasite-induced thrombophilia and immune down modulation, which can complicate the presentation of vascular lesions and the surgical management, leading to thrombosis or co-infection.

These specific features of arterial lesions in patients with schistosomiasis are a call to integrate programs with a cardiovascular prevention and a morbidity management plan in areas which are endemic for this parasitosis.