Eosinophilic pneumonia

Alternative names
Pulmonary infiltrates with eosinophilia; Simple pulmonary eosinophilia; Loeffler’s syndrome


Simple pulmonary eosinophilia is characterized by abnormal chest X-ray findings. These vary - the abnormality may appear in one part of the lung at one time, but the next X-ray may show no pathology or a problem in a different part of the lung.

The abnormal X-rays are accompanied by a rise in the number of eosinophils (a type of white blood cell that is probably involved in allergies) in the blood. The disease usually clears up without treatment.

Causes, incidence, and risk factors

Simple pulmonary eosinophilia appears to be caused by an allergic reaction. A common cause is the migration of the parasitic worm Ascaris lumbricoides through the respiratory tract. Proteins on the surface of the worm probably incite this allergic reaction.

Other parasites of the ascaris family may also cause the syndrome. Additional possible causes include allergies to medications such as sulfonamide antibiotics.


  • General ill feeling (malaise)  
  • Fever  
  • Dry cough  
  • Chest pain  
  • Shortness of breath  
  • Wheezing  
  • Rapid respiratory rate  
  • Rash

Note: Symptoms range from none at all to severe. They will usually go away without treatment.

Signs and tests

  • Listening to the chest with a stethoscope may reveal rales(crackle-like sounds that suggest inflammation of the lung tissue).  
  • A bronchoscopy with washing may show a large number of eosinophils.  
  • Sputum, bronchoscopically obtained washing, and gastric lavage may reveal larvae of the ascaris worm.  
  • A CBC or WBC count shows increased white blood cells, particularly eosinophils.  
  • Chest X-ray usually reveals abnormal shadows (infiltrates) that disappear with time, or may reappear in different areas of the lung.

If a cause is found, therapy consists of removing the offending drug or treating the infection with antibiotic or antiparasitic medication.

Expectations (prognosis)
The disease often resolves without treatment. If treatment is needed, the response is usually good. However, relapses can occur.


A rare complication of simple pulmonary eosinophilia is severe pneumonia.

Calling your health care provider
See your health care provider if you have symptoms that may be linked with this disorder.

This is a rare disorder. Many times, the cause cannot be found. Minimizing exposure to possible risk factors (certain medicines, some metals) may reduce risk.

Johns Hopkins patient information

Last revised: December 4, 2012
by Janet G. Derge, M.D.

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