Tularemia test; Serology for Francisella tularensis
Tularemia blood test checks for infection caused by bacteria called Francisella tularensis (F tularensis). The bacteria 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 are proteins that 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 specific for F tularensis 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 provider 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.
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another, and from one side of the body to the other. Taking blood 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
- Multiple punctures to locate veins
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Aoyagi K, Ashihara Y, Kasahara Y. Immunoassays and immunochemistry. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 44.
Chernecky CC, Berger BJ. Tularemia agglutinins - serum. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:1052-1135.
Penn RL. Francisella tularensis (tularemia). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 229.