The measurement of IgM antibodies against Francisella tularensis is used as an aid in the diagnosis of tularemia.
Francisella tularensis is an aerobic, Gram negative, non-motile and non-sporogenic microbe. It is the causative agent of tularemia, a highly infectious disease for humans and rabbits. Francisella tularensis has circular DNA and contains less than 2000 genes. There are several subspecies of the bacterium that vary in degree of infectivity. The highly infectious strain of Francisella tularensis type A is found mainly in North America, while the least virulent strain of Francisella tularensis palaearctica type B is found in Europe and Asia. There are two more non-infectious strains found in Central Asia.
Francisella tularensis uses arthropods as carriers to infect humans and animals, but it can also be transmitted through the air. Infection occurs through the mucous membranes of the lung and the gastrointestinal tract as well as through the skin. After the initial infection, the microbe migrates to organs such as lymph nodes, liver, spleen, and lungs. Within the body, the bacterium infects the macrophages that phagocyte it, multiply, and then destroy the cell, releasing new bacteria ready to infect other cells.
Infection with Francisella tularensis results in a debilitating disease even at low levels of infection. Symptoms can vary depending on the type of infection, with the most common type, being through insect bites, causing ulceration at the site of the bite accompanied by fever, chills, headache, and fatigue. Infection through inhalation causes typhoid disease with fever, fatigue, weight loss, and pneumonia.
There is no vaccine available for tularemia and most cases are treated with antibiotics.
False-positive results may occur in patients previously or currently infected with Brucella species. Other less frequent causes of cross-reactivity that have been reported include prior infection with Yersinia, Salmonella, or Legionella species.
IgM-class antibodies may be detectable as soon as 1 week after symptom onset and may remain detectable for multiple years following resolution of disease in some individuals. Therefore, an IgM-positive result may not indicate a current or recent infection in some cases.
Important Note
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.
