Pulmonary arterial hypertension associated with schistosomiasis

Pulmonary arterial hypertension associated with schistosomiasis (Sch-PAH) is a form of pulmonary arterial hypertension (PAH) that develops as a complication of chronic infection with Schistosoma species, most commonly Schistosoma mansoni and Schistosoma japonicum. Schistosomiasis is a parasitic disease caused by blood flukes (trematodes) that affects over 200 million people worldwide, particularly in tropical and subtropical regions. In a subset of patients with the hepatosplenic form of schistosomiasis, pulmonary vascular disease develops, making schistosomiasis one of the most common causes of PAH globally. The disease primarily affects the pulmonary vascular system. Schistosome eggs embolize to the lungs through portosystemic collateral vessels that develop due to portal hypertension, triggering a complex inflammatory and immune-mediated response in the pulmonary vasculature. This leads to vascular remodeling, including intimal fibrosis, medial hypertrophy, and plexiform lesions similar to those seen in idiopathic PAH. The resulting increase in pulmonary vascular resistance places strain on the right side of the heart. Key symptoms include progressive exertional dyspnea (shortness of breath), fatigue, chest pain, syncope (fainting), peripheral edema, and signs of right heart failure. Patients may also exhibit features of underlying hepatosplenic schistosomiasis, such as hepatomegaly and splenomegaly. Treatment involves a combination of antiparasitic therapy (praziquantel) to treat the underlying schistosomal infection and PAH-targeted therapies. PAH-specific medications such as phosphodiesterase-5 inhibitors (e.g., sildenafil), endothelin receptor antagonists (e.g., bosentan), and prostacyclin analogs have been used with some evidence of benefit, though large-scale clinical trials specific to this population are limited. Supportive care including diuretics and supplemental oxygen may also be necessary. Early diagnosis and treatment of schistosomiasis remain critical for prevention. The prognosis of Sch-PAH appears to be somewhat better than that of idiopathic PAH, though it remains a serious and potentially life-threatening condition.

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