Does this test have other names?

Haemophilus influenzae type b (Hib) IgG antibody level

What is this test?

This test measures the amount of anti-Hib IgG immunoglobulin, or antibody, in your blood.

There are many types of Haemophilus influenzae bacteria. They can live in your mouth, throat, ears, and airways and don't always cause illness. The bacteria spread from person to person via airborne droplets or direct contact with an infected person's respiratory fluids. H. influenzae type b (Hib) is one of the most serious types. It doesn't cause the flu, although it has a similar-sounding name. It can cause bacterial meningitis. This is an infection of the covering of the brain. Hib can also cause different types of infections, such as ear and sinus infections and some types of pneumonia. It can make COPD (chronic obstructive pulmonary disease) worse. Adults who smoke or have underlying health conditions, such as HIV, cancer, or pregnancy, have an increased risk of getting H. influenzae disease. 

In general, Hib infection is passed through coughing, sneezing, or contact with infected body fluids.

Before 1990, Hib was the leading cause of bacterial meningitis in children younger than age 5. The Hib vaccine is now routinely given to children to prevent infection.

This test can find out whether your body has responded to the Hib vaccine. It's usually done if your immune system isn't working the way it should.

Why do I need this test?

You may need this test if your healthcare provider isn't sure whether you have developed immunity against Hib after getting the vaccine. You may also get this test both before and a few weeks after a dose of Hib vaccine to measure changes in the amount of Hib antibodies your body is able to make.

What other tests might I have along with this test?

Your healthcare provider may also order other tests, including:

• Complete blood count, or CBC

• Immunoglobulin levels, or IgG, IgA, and IgM

• Other specific antibody levels, such as antibodies against Streptococcus pneumoniae

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

A positive result means that antibodies were found in your blood. That means that you are or were recently infected with Hib or that your immune system was able to respond well to the Hib vaccine. Your healthcare provider will make a final diagnosis based on a physical exam, your symptoms, and other test results.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.

What might affect my test results?

If you have other bacteria in your blood, you may have a false-positive on this test. These bacteria include E. coli and S. pneumonia.

How do I get ready for this test?

You don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.