An Outbreak of Acute Schistosoma mansoni Schistosomiasis in a Nonendemic Area of Brazil: A Report on 50 Cases, Including 5 With Severe Clinical Manifestations

Abstract

Acute schistosomiasis is a systemic hypersensitivity reaction against the migrating schistosomula and eggs. In this report, we describe an atypical outbreak of the disease with severe cases. Transmission occurred in a nonendemic area of Brazil, which became a new focus of transmission due to the in-migration of infected workers. From December 2009 to March 2010, the 50 patients with acute schistosomiasis (group 1) bathed in a swimming pool supplied by a brook on a country estate in the outskirts of São João del Rei, Brazil. Thirty other subjects (group 2) living in the same area, who denied having contact with the swimming pool, volunteered to participate in the study. All participants were submitted to clinical, laboratory, and ultrasound examinations. Five of 50 (10%) patients were admitted to the hospital: 1 with myeloradiculopathy, 1 with diffuse pulmonary micronodules, and 3 with diarrhea and dehydration. All 5 had hypereosinophilia and prolonged fever. Group 1 patients more frequently had cercarial dermatitis (P = .01), blood in the stool (P = .04), and intra-abdominal lymph nodes (P = .001). All group 1 patients were treated with praziquantel; 1 patient with myeloradiculopathy also received oral prednisone (60 mg/day) for 6 months with complete recovery. This report describes the first time that patients from an outbreak of acute schistosomiasis have been compared to controls. Five subjects (10%) had severe manifestations of schistosomiasis. Diagnosis of the disease and its severity was delayed because physicians did not consider that an epidemic of schistosomiasis might emerge in a nonendemic area.