Your body makes antibodies when you are exposed to bacteria, viruses, or other foreign substances. Antibodies are specific to a disease, so they can be used to identify current and past infections.
Technically, serology means testing the clear part of the blood, the serum. However, serology for a suspected infectious disease means looking for an immune response or antibodies to a specific infection.
In other words, serology for tularemia is a blood test looking for antibodies to tularemia. That test is also called a Francisella tularensis antigen assay. F. tularensis is the bacteria that cause tularaemia.
Tularemia serology may be ordered if exposure to tularemia is suspected or if a patient is showing symptoms. Tularemia is a rare disease that causes a high fever. It is carried by wild animals, but can also be spread by ticks, mosquitoes, and other biting flies.
Serology for tularemia is a quick and simple test. The risks are very low.
Tularemia is bacterial infection also known as:
- lemming fever
- rabbit fever
- O’Hara’s disease
Symptoms often appear very suddenly. They tend to emerge a few days after exposure. Some symptoms of tularemia are:
- high body temperature
- pain in the muscles
- stiffness in the joints
- trouble breathing
- irritation in the eye area
- sore throat
Tularemia can be a very serious illness. The good news is that it is rare. According to the Centers for Disease Control and Prevention (CDC), there are only about 120 reported cases each year in the United States (CDC, 2011).
Although tularemia is very serious, it is not often fatal. In untreated patients, tularemia is fatal in only about five percent of cases. With treatment, that number falls to roughly one percent.
The bacteria that cause tularemia are transmitted from infected animals to humans. This can occur in a number of ways, including:
- being bitten by an infected tick or deer fly
- drinking water that contains the bacteria
- inhaling dirt or vegetative matter containing the bacteria
- eating the meat of an infected animal
- being in direct contact with an infected animal
Both live and dead animals can transmit tularemia. Animals that are likely to be infected include:
- wild rodents
There is no special preparation for the test. When you arrive, a technician will insert a needle into a vein to collect your blood. Your blood will then be sent to a lab.
This is a simple test. It will not cause any significant problems for most people. Tell the person collecting your blood if you have a bleeding disorder or know you feel faint at the sight of blood.
Normal Test Results
Negative tularemia serology means there were no antibodies in the sample. This usually means you are not infected. However, it could also mean that the antibodies have not had time to develop yet. Antibodies may not appear for a few weeks after infection.
Abnormal Test Results
If your blood tests positive for antibodies, you may be infected with tularemia. However, you also might have been infected in the past. A positive test does not necessarily mean a current infection.
Your doctor will decide whether any further testing is needed. Other tests to diagnose tularemia do exist. Your doctor might also decide to wait a few weeks and repeat the antibody test.
There are two reasons to repeat tularemia serology.
If you had a negative test, repeating it gives the test time to turn positive after a recent infection.
If you had a positive test and your antibody levels go up, it probably means you have an active infection
Most people diagnosed with tularemia are treated with antibiotics. Medication is usually taken for 10 to 21 days. People may feel the effects of a tularemia infection for as long as a few weeks. However, most will make a full recovery.