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Introduction ⬇

Tularemia, also known as “rabbit fever,” is primarily found in rural areas, although occasionally it occurs in urban and suburban areas. Tularemia is caused by the bacterium Francisella tularensis, an intracellular parasite (aerobic, Gram-negative coccobacillus). Two major subspecies of F. tularensis have been identified: type A (F. tularensis biovar tularensis), which is highly virulent in humans, and type B (F. tularensis biovar palaearctica), which is relatively avirulent.

Once infected, person-to-person transmission has not been documented. However, humans can contract F. tularensis through the skin, mucous membranes, lungs, and GI tract by contact with infected animals (e.g., mice, squirrels, rabbits) or contaminated water, soil, and vegetation. Animals become infected through tick, fly, and mosquito bites. Because F. tularensis is highly infectious (10–50 organisms can cause disease), its use in biologic terrorism cannot be overlooked. The incubation period is usually 3–5 days but can be as long as 14 days, followed by an abrupt onset of symptoms, including fever, chills, and headaches. Mortality can be as high as 30% if not treated and 10% if treated.

This test is used to determine the presence of the F. tularensis organism.

Procedure ⬆ ⬇

  1. Obtain specimens of respiratory secretions (i.e., sputum), blood, lymph node biopsy samples, or scrapings from infected ulcers.

  2. Collect sputum samples after a forced deep cough and place in a sterile, screw-top container.

  3. Obtain a 5- to 7-mL Vacutainer from a venipuncture for blood samples.

  4. Obtain a skin scraping at the leading edge of a lesion from an infected ulcer and place in a clean, screw-top tube.

  5. Perform presumptive identification of F. tularensis in a BSL-2 laboratory.

  6. Ensure that confirmation of the organism is done in a BSL-3 clinical laboratory. BSL-3 laboratories process indigenous or exotic agents with a potential for respiratory transmission and causation of serious or lethal infection.

Procedural Alert

  1. Observe standard precautions.

  2. Contaminated clothing or linens should be disinfected per standard precautions protocols.

  3. Decontaminate surfaces with a 10% bleach solution.

  4. Laboratory personnel who may have had a potential infective exposure should be given prophylactic antibiotic drugs if the risk for infection is high (e.g., needlestick).

Clinical Implications ⬆ ⬇

Identification of F. tularensis and increased antibody titers indicate the presence of tularemia. Antibodies do not appear until 2–3 weeks after exposure and peak at about 5 weeks.

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain the purpose, procedure, and risks of obtaining a specimen. Assess for and document signs and symptoms of infection (ulcer at site of infection, swollen lymph nodes, fever, chills, headache, fatigue), history of urban or rural living, and occupation (e.g., handling infected animal carcasses).

  2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. If the F. tularensis organism is cultured from the patient, isolation is not recommended because human-to-human transmission has not been documented.

  2. Review test results; report and record findings. Modify the nursing care plan as needed. Counsel the patient and monitor appropriately.

  3. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Clinical Alert

  1. Suspicion of inhalational tularemia (i.e., signs and symptoms) must be reported to local or state public health authorities and the CDC.

Reference Values ⬆

Normal

Absence of the F. tularensis organism

Negative serum antibody titers