A retrospective study of schistosomiasis-associated pulmonary hypertension from an endemic area in Brazil

and 2010 at a center in Pernambuco, Brazil, a state where schistosomiSchistosomiasis is a parasitic disease caused by trematode flatworms of the genus Schistosoma [1]. Schistosomiasis is the thirdmost prevalent endemic parasitic disease and themost common parasitic disease associated with pulmonary hypertension in theworld [2]. An estimated 240 million people are infected and 800 million at risk for infection. Despite its clinical importance, schistosomiasis continues to be a global public health problem in the developing world, and is considered a neglected tropical disease. Schistosomiasis has two phases, acute and chronic. Acute symptoms start ~50 days after exposure, characterized by fever, abdominal pain and constitutional symptoms [3]. In this phase the inflammatory response is characteristically a T helper 1 (Th1) cell response. After the parasite starts laying eggs, chronic disease begins with variable presentation, with forms including hepatointestinal, hepatosplenic, pulmonary arterial hypertension (PAH), glomerulonephritis and neuroschistosomiasis [1]. The chronic phase is characterized by a Th2 cell response, including the cytokines IL4, IL5, IL10, and IL13 [2,4]. PAH is a rare disease, characterized by increased pressure in the pulmonary circulation and right ventricular overload [5]. Schistosomaassociated PAH is classified among the World Health Organization (WHO) Group 1 PAH, and its pathophysiology seems similar to other etiologies of this group including idiopathic, heritable, HIV and autoimmune forms. Schistosoma-associated PAH is a complication of hepatosplenic schistosomiasis, as hepatic fibrosis and portal hypertension leads to opening of portocaval shunts and embolization of Schistosoma eggs to the pulmonary vasculature. The impacted eggs stimulate an immunological reaction leading to the development of granuloma, and vascular remodeling. The pathophysiology of Schistosoma-PAH is still poorly understood: vascular obstruction by the eggs does not account for all changes observed. It is likely that the host immune system contribues to the vascular disease, as an apparent unintended side effect. Among those chronically infected, ~10% develop hepatosplenic disease and of these ~8 to 10% develop PAH [2]. There is scarce information regarding the natural history of schistosomiasis-PAH (Sch-PAH). In 2010, Fernandes et al reported the outcomes of a retrospective cohort of Sch-PAH patients, and reported