Tularemia test; Serology for Francisella tularensis
Serology for tularemia is a blood test that checks for infection caused by bacteria called Francisella tularensis (F tularensis), which causes the disease tularemia.
A blood sample is needed.
The sample is sent to a laboratory where it is examined for francisella antibodies using a method called serology. This method checks if your body has produced substances called antibodies to a specific foreign substance (antigen), in this case F tularensis.
Antibodies defend your body against bacteria, viruses, and fungi. If antibodies are present, they are in the serum of your blood. Serum is the liquid portion of blood.
How to Prepare for the Test
There is no special preparation.
How the Test will Feel
When the needle is inserted to draw blood, you may feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or bruising. This soon goes away.
Why the Test is Performed
This blood test is done when tularemia is suspected.
A normal result is no antibodies are found in the serum.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
If antibodies are detected, there has been exposure to F tularensis.
If antibodies are found, it means you either have a current or past infection with F tularensis. In some cases, a single high level of antibodies that are specific to F tularensis means you have an infection.
During the early stage of an illness, few antibodies may be detected. Antibody production increases during the course of an infection. For this reason, this test may be repeated several weeks after the first test.
Veins and arteries vary in size from one patient to another, and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Ashihara Y, Kasahara Y, Nakamura RM. Immunoassays and immunochemistry. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 44.
Penn RL. Francisella tularensis (Tularemia). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 229.