A 19-year-old woman arrived by ambulance at a hospital in southeastern Iran, drifting in and out of awareness, vomiting, and fighting for breath. Her oxygen saturation was 75 percent. Her pulse was 145. The emergency team's first working diagnosis was acute pulmonary edema.
A high-resolution CT scan of her chest told a different story. A thin-walled cyst measuring 150 by 93 millimeters, close to six inches at its longest, sat in the lower lobe of her left lung with an air-fluid level inside it. It had collapsed the lobe above and shoved her heart and mediastinum toward the right side of her chest. The cyst was the larval stage of a tapeworm.
