Medically Managed Locally Acquired Pulmonary Cystic Echinococcosis With Bacterial Superinfection in Northern Canada: A Case Report.

Background: Primary pulmonary cystic echinococcosis (CE) is a zoonotic disease often caused by Echinococcus granulosus sensu lato complex. Although rare in North America, it can present significant diagnostic and therapeutic challenges. Case Presentation: We report a 36-year-old male from Quebec, Canada, with locally acquired primary pulmonary CE who presented to the emergency department with a two-month history of shortness of breath, cough, and hemoptysis. Laboratory investigations showed mild leukocytosis and high eosinophil counts. A chest computed tomography (CT) scan revealed extensive multifocal consolidation in the right upper lobe (RUL) with a large 6-cm thick-walled cavity. Echinococcus serology was positive. Treatment was initiated with albendazole and praziquantel as well as antibiotics for pulmonary CE, with likely ruptured cyst and bronchoalveolar spillage complicated by a superimposed bacterial infection of the RUL. Follow-up imaging showed a decrease in the size of the cavitary lesion and regression of adjacent consolidations. Discussion: Diagnosing and managing pulmonary CE is complex, as clinical presentations vary and imaging and serological tests have limitations. Treatment depends on factors such as cyst size, rupture status, and infection, with surgery as the main approach for viable cysts and albendazole used for ruptured cysts. Conclusion: Pulmonary CE requires individualized management due to its varied presentations, with imaging and serology playing key but limited roles in the diagnosis. Medical management and monitoring were effective, while surgery was reserved for complex cases, with long-term follow-up and family screening essential for detecting recurrence and asymptomatic cases.