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Tick-Borne Diseases, Tularemia: Differential Diagnoses & Workup
Updated: Dec 9, 2008
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Differential Diagnoses
Other Problems to Be Considered
Psittacosis
Brucellosis
Q fever
Legionella pneumonia
Workup
Laboratory Studies
- Results of standard blood tests are nondiagnostic.
- WBC count usually is normal or elevated. No consistent abnormality is found in other components of the CBC count.
- In one series, urinalysis revealed pyuria in nearly one quarter of the cases.2
- Serum chemical analysis reveals elevation of at least 1 test of hepatic function in about 50% of patients. An elevated creatine kinase level is associated with rhabdomyolysis and is a poor prognostic sign.
- Examination of the spinal fluid occasionally reveals an elevated protein level or a mild pleocytosis.
- Findings with routine blood cultures usually are normal because the organism has unique growth requirements. Similarly, while the organism is present in the ulcers, it rarely grows in cultures.
- The sputum of patients with tularemic pneumonia usually is white and does not reveal the pathogen.
Imaging Studies
- A chest radiograph is indicated, because roughly 30% of patients with tularemic pneumonia do not have respiratory symptoms. Overlap with other atypical pneumonias may exist.
Other Tests
- Definitive diagnosis usually is established with serologic testing. This is in part because the organism is often not present in large numbers in blood or sputum and, in any case, may be difficult to cultivate.
- Notifying the hospital laboratory staff is important if tularemia is a serious differential diagnostic possibility, because the organism can grow on normal culture media and many episodes of laboratory technician disease have been reported. The organism should only be worked with in culture in a Biosafety Level 3 facility.
- A 4-fold increase in the titer or a single titer of 1:160 or more is the common threshold, although this varies with the laboratory. The methods also vary from antibody detection by latex agglutination or enzyme-linked immunosorbent assay (ELISA) testing to a range of polymerase chain reaction (PCR) products that directly measure DNA from the organisms.
- One study revealed that no patient had a diagnostic titer before the 11th day of illness, but nearly all had one by day 16.2 Therefore, in interpreting the result, one must factor in the timing of the serologic test.
- Rabbit handlers and others may have an asymptomatic elevation in antitularemic antibody titers without disease; thus, the elevated titer in the absence of clinical tularemia does not establish a diagnosis.
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| Overview: Tick-Borne Diseases, Tularemia |
 Differential Diagnoses & Workup: Tick-Borne Diseases, Tularemia |
| Treatment & Medication: Tick-Borne Diseases, Tularemia |
| Follow-up: Tick-Borne Diseases, Tularemia |
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References
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Evans ME, Gregory DW, Schaffner W, McGee ZA. Tularemia: a 30-year experience with 88 cases. Medicine (Baltimore). Jul 1985;64(4):251-69. [Medline].
Perez-Castrillon JL, Bachiller-Luque P, Martin-Luquero M, et al. Tularemia epidemic in northwestern Spain: clinical description and therapeutic response. Clin Infect Dis. Aug 15 2001;33(4):573-6. [Medline].
Craven RB, Barnes AM. Plague and tularemia. Infect Dis Clin North Am. Mar 1991;5(1):165-75. [Medline].
Dennis DT, Inglesby TV, Henderson DA, et al. Tularemia as a biological weapon: medical and public health management. JAMA. Jun 6 2001;285(21):2763-73. [Medline].
Eliasson H, Broman T, Forsman M. Tularemia: current epidemiology and disease management. Infect Dis Clin North Am. Jun 2006;20(2):289-311, ix. [Medline].
Ellis J, Oyston PC, Green M, Titball RW. Tularemia. Clin Microbiol Rev. Oct 2002;15(4):631-46. [Medline].
Ikaheimo I, Syrjala H, Karhukorpi J, et al. In vitro antibiotic susceptibility of Francisella tularensis isolated from humans and animals. J Antimicrob Chemother. Aug 2000;46(2):287-90. [Medline].
Jacoby I. Francisella tularensis (tularemia) attack. In: Ciottone G, ed. Disaster Medicine. Philadelphia, Pa: Mosby; 2006.
Langley R, Campbell R. Tularemia in North Carolina, 1965-1990. N C Med J. Jul 1995;56(7):314-7. [Medline].
Limaye AP, Hooper CJ. Treatment of tularemia with fluoroquinolones: two cases and review. Clin Infect Dis. Oct 1999;29(4):922-4. [Medline].
Nigrovic LE, Wingerter SL. Tularemia. Infect Dis Clin North Am. Sep 2008;22(3):489-504, ix. [Medline].
Penn RL, Kinasewitz GT. Factors associated with a poor outcome in tularemia. Arch Intern Med. Feb 1987;147(2):265-8. [Medline].
Schmid GP, Kornblatt AN, Connors CA, et al. Clinically mild tularemia associated with tick-borne Francisella tularensis. J Infect Dis. Jul 1983;148(1):63-7. [Medline].
Staples JE, Kubota KA, Chalcraft LG. Epidemiologic and molecular analysis of human tularemia, United States, 1964-2004. Emerg Infect Dis. Jul 2006;12(7):1113-8. [Medline].
Further Reading
Keywords
tick-borne disease, tularemia, Francisella tularensis, F tularensis, ulceroglandular, glandular, oculoglandular, oropharyngeal, pneumonic, typhoidal, rabbit fever, deer-fly fever, vector-borne disease, tularensis strain
