English: This AP chest x-ray reveals the early stages of bilateral pulmonary effusion due to hantavirus pulmonary syndrome (HPS), also referred to as hantavirus cardiopulmonary syndrome (HCPS). Radiologically, HPS begins with interstitial pulmonary edema, progressing to alveolar edema with severe bilateral involvement. Pleural effusions are common, and are often large enough to be evident radiographically.