A rare pneumonia is a type of lung infection that is not commonly seen. There are different types of rare pneumonia, including eosinophilic pneumonia, which is a group of rare infections that affect the lungs. Eosinophilic pneumonia is caused by a type of white blood cell that builds up in the lungs and blood, causing inflammation and damage. It can be caused by smoking, allergic reactions, and parasitic infections. Acute eosinophilic pneumonia (AEP) is a rare disorder characterized by the rapid accumulation of eosinophils in the lungs. Chronic eosinophilic pneumonia (CEP) is a rare disorder characterized by the massive accumulation of eosinophils in the lungs. Symptoms of eosinophilic pneumonia can include fever, chest pain, shortness of breath, cough, and a general feeling of illness. Diagnosis of eosinophilic pneumonia can involve chest x-rays, computed tomography, bronchoscopy, and blood tests to measure the number of eosinophils. Treatment can involve medications to ease symptoms and prevent respiratory failure.