Rapid Fluorescent Focus Inhibition Test (RFFIT)-Why am I having this test?

Rapid fluorescent focus inhibition test is a blood test to check your body’s ability to fight (immunity to) the rabies virus. Rabies is a dangerous viral infection that spreads from infected animals to humans, usually from an animal bite. There is no cure for this infection once symptoms develop.

People who may have been exposed to rabies through work or an animal bite are treated with multiple rabies vaccines (vaccination series). These are injections that help your body make antibodies to the rabies virus.

Antibodies are proteins that are part of the body’s disease-fighting system (immune system). They help your body fight infections. RFFIT is done to make sure that your level of antibodies is high enough to fight a rabies infection after having the vaccination series.

You may need this test if you have been given the vaccination series and:

• You work with animals that may carry the rabies virus.
• You work in a lab that handles samples of the rabies virus.
• The quality or timing (schedule) of your vaccinations may be questionable.
• You have a weak immune system that may not be able to make enough antibodies in response to the vaccine.

What is being tested?

This test measures the ability of rabies virus neutralizing antibodies (RVNA) in your body to inactivate (neutralize) the rabies virus. RVNAs prevent the rabies virus from infecting cells.

What kind of sample is taken?

A blood sample is required for this test. It is usually collected by inserting a needle into a blood vessel.

Tell a health care provider about:

• When and where you had your rabies vaccination series.
• Any allergies you have.
• All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.
• Any blood disorders you have.
• Any surgeries you have had.
• Any medical conditions you have.
• Any possibility of a weakened immune system.
• Whether you are pregnant or may be pregnant.

How are the results reported?

Your test results will be reported as one of the following:

• A ratio that describes the concentration of RVNA in the liquid part of your blood (serum titer).
• International units of antibody per milliliter of serum (IU/mL).

Your health care provider will compare your results to normal values that were established after testing a large group of people (reference values). Reference values may vary among labs and hospitals. For this test, common reference values are:

• A serum titer of 1:5 or greater.
• An IU value of 0.11 IU/mL or greater.

What do the results mean?

A serum titer of at least 1:5 and an IU value of at least 0.11 IU/mL, after receiving the rabies vaccination series, means that you have enough antibodies in your blood to neutralize the rabies virus. These results mean that you are adequately immune to the rabies virus.

If your titer is lower than 1:5 or your IU value is below 0.11 IU/mL, this means that you are not adequately immune to the rabies virus. You may need a booster dose of the rabies vaccine.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• How often should I repeat this test?

Summary

• A rapid fluorescent focus inhibition test (RFFIT) is a blood test that checks your resistance to the rabies virus. It is done after you have had a rabies vaccination series.
• You may need this test if you are a veterinarian or you work in a lab that handles samples of the rabies virus.
• Results of this test tell whether you are protected from rabies virus infection. If you are not protected, you may need a booster dose of rabies vaccine.
• Talk with your health care provider about what your results mean.