Does this test have other names?
Legionnaires' disease antibody test, Legionella antibody assay
What is this test?
This test looks for an antibody that may be in your blood if you have Legionnaires'
Legionnaires' disease is a type of pneumonia or serious lung infection caused by bacteria
Antibodies are proteins that your immune system makes to fight infection or foreign
invaders. The bacteria and the disease get their name because of an outbreak that
occurred among people attending an American Legion convention in Philadelphia in 1976.
Why do I need this test?
You might have this test to see if your healthcare provider suspects that you have
Legionnaires' disease. Or you may have this test if your provider thinks you have
a milder form of infection known as Pontiac fever. Symptoms of Legionnaires' disease
Symptoms may begin 2 days to 2 weeks after you are exposed to the bacteria.
You may need this test again in several weeks to confirm your diagnosis or to see
whether you have recovered.
What other tests might I have along with this test?
Your healthcare provider might also order a chest X-ray to diagnose pneumonia. He
or she might also take a sample of your mucus or lung tissue for a culture test, and
order a urine test to look for Legionella.
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses
to do the test. Even if your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
Normal results are negative. This means no Legionella antibody was found in your blood.
A positive result means that Legionella antibodies were found. You may have Legionnaires'
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection,
bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight
stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
If the test is done too early after you are infected, you may have a false-negative
How do I get ready for this test?
You don't need to prepare for this test.