Is there an antibody test that can be used to diagnose pneumonia many months ago?

I had pneumonia (shown on chest x-ray, single-lobe/105°F fever) 5 months ago. Is there a test for the Legionnaires’ disease antibodies that can be taken at this point to prove or disprove that it was Legionnaires’ disease? I still feel tired and breathless most of the time. I have had diarrhea for quite a while now. My doctors don’t think it is an issue.

You can have a blood test for Legionella performed (Legionella serology for antibodies). If the test is positive, this is circumstantial evidence that the pneumonia was Legionnaires’ disease.

Your doctors may be right about the issue of Legionnaires’ disease. You have been treated successfully and you need no further antibiotics. In the FAQs, we provide information that many patients who contract Legionnaires’ disease will experience fatigue for more than a year, although almost all will recover. Diarrhea is common, but it should resolve when the pneumonia resolves, so consult your physician if it has not resolved. Clostridium difficile colitis is a syndrome caused by antibiotics and this diagnosis might be considered. We recommend that patients with Legionnaires’ disease quit smoking and continue to be active even if they feel fatigued.