Pulmonary Alveolar Proteinosis-Like Presentation of Murine Typhus in a Previously Healthy Adult

Rickettsia typhi-induced murine typhus is underrecognized in southern U.S. regions such as Texas. While typical symptoms include fever, rash, and mild pulmonary involvement, severe presentations such as pneumonia or acute respiratory distress syndrome (ARDS) can occur. The radiographic "crazy-paving" pattern is nonspecific and can be seen in a variety of infectious and inflammatory pulmonary conditions, creating diagnostic uncertainty. Because pulmonary alveolar proteinosis (PAP) typically prompts consideration of invasive diagnostic evaluation, recognizing infectious mimics has important clinical implications. A 46-year-old man with alcohol use disorder develops fatigue, cough, dysuria, dyspnea, and fever. CT imaging revealed bilateral perihilar ground-glass opacities with interlobular septal thickening ("crazy-paving"). Laboratory studies showed leukocytosis, thrombocytopenia, acute kidney injury, transaminitis, and elevated inflammatory markers. Broad-spectrum antibiotics did not provide symptom relief. Serologic testing confirmed murine typhus; doxycycline led to rapid clinical and radiographic improvement. Four-week follow-up imaging showed near-complete resolution. This is, to our knowledge, the first reported case of murine typhus presenting with radiological and clinical features that closely mimic pulmonary alveolar proteinosis. In endemic regions, murine typhus should be included in the differential diagnosis of diffuse alveolar disease with a crazy-paving pattern, as this overlap may lead to diagnostic uncertainty and potentially unnecessary invasive evaluation. Early recognition and treatment with doxycycline can result in rapid clinical and radiographic resolution.