Updated: Dec 9, 2008
First described in Japan in 1837, tularemia is an infectious disease caused by the gram-negative pleomorphic bacterium, Francisella tularensis. The disease name relates to the description in 1911 of a plaguelike illness in ground squirrels in Tulare County, California, and the subsequent work performed by Dr Edward Francis. In 1928, Francis described his personal experience with more than 800 cases.
F tularensis is found worldwide in more than 100 species of wild animals, birds, and insects. This occurs in both terrestrial (rabbits, hares, ticks, and flies) and aquatic animals (muskrats and beavers). Four major strains, which differ in both virulence and geographic range, exist. The "tularensis" strain, found primarily in North America, is the most virulent.
The organism produces an acute febrile illness in humans. The route of transmission and factors relating to the host and the organism influence the presentation.
| Clinical Image Atlas Click to view clinical images on the features, causes, epidemiology, diagnosis, and treatment of Lyme disease. |
Categories of tularemia
Some authorities classify tularemia into 2 groups, which include the far more common ulceroglandular form (in which local or regional symptoms and signs predominate) and the more lethal typhoidal form (in which systemic symptoms dominate the clinical picture). More commonly, however, tularemia is divided into 6 forms:
Each form reflects the mode of transmission. The organism gains access to the host by means of inoculation into skin or mucous membrane, inhalation, or ingestion. Although person-to-person transmission does not occur with F tularensis, the organism is extremely infectious, with as few as 10-50 inhaled organisms producing disease. It is therefore an organism that can infect laboratory technicians working with the organism, making it a candidate for use as a biological weapon.
Ulceroglandular form (70-80% of cases): The organism enters through a scratch, abrasion, or tick or insect bite and spreads via the proximal lymphatic system. Within the ulceroglandular form, more differentiation exists. A subcutaneous inoculum of as few as 10 organisms can cause disease.
Glandular form (rare): No ulcer is present, and the organism is presumed to have gained access to the lymphatic system and/or bloodstream through clinically unapparent abrasions.
Oculoglandular form (1% of cases): The organism enters through the conjunctiva from either a splash of infected blood or rubbing the eyes after contact with infectious materials (eg, blood from a rabbit carcass).
Oropharyngeal form (rare): This form occurs after ingestion of eating undercooked rabbit meat containing the organism.
Pneumonic form (uncommon): This form occurs when the organism is inhaled. This form is observed in laboratory workers and occasionally occurs naturally. Pneumonia also occurs in 10-15% of patients with ulceroglandular tularemia and in one half of those patients with typhoidal tularemia.
Typhoidal (or septicemic) form (10-15% of cases): This form is more severe than the others and often includes pneumonia. Ingestion may be the mode of transmission; however, in most cases, the portal of entry remains unknown.
Incubation
After an incubation period of 3-4 days (range, 1-14 d), a papule develops, accompanied by a high fever. The papule evolves into an ulcer associated with regional lymphadenopathy. Some patients infected by a second, less virulent strain (type B) have less dramatic presentations.
Carriers
Although numerous animals and insects can carry F tularensis, rabbits and ticks (especially Dermacentor and Amblyomma species) most commonly are implicated in human cases. The deer fly is another classic, although less common, vector.
A few hundred cases of tularemia are reported annually in the United States. As with most such diseases, most cases are likely unreported or misdiagnosed. Although sporadic cases occur in all states, those with highest prevalence are Arkansas, Illinois, Missouri, Texas, Oklahoma, Utah, Virginia, and Tennessee. Some occupations confer risk for tularemia; they include laboratory workers, landscapers, farmers, veterinarians, hunters, trappers, cooks, and meat handlers.
The frequency of tularemia has decreased markedly over the last 50 years, and a shift from winter disease (usually from rabbits) to summer disease (more likely from ticks) has occurred. Although this decrease led to the Centers for Disease Control and Prevention (CDC) removing tularemia from its list of reportable diseases in 1994, it was reinstated in 2000 due to concerns about tularemia being used as a biological weapon.
Tularemia is found worldwide, but the incidence is unknown.
Untreated, tularemia has a mortality rate of 5-15%; this rate is even higher with the typhoidal form. Appropriate antibiotics lower this rate to about 1%.
Biologically, no gender bias exists; however, young–to–middle-aged men may be more likely to engage in activities (eg, associated with tick bites, rabbit, and wild game exposure) that predispose them to tularemia. Recently, tularemia has been associated with the bite of a pet hamster.1
Physical findings in tularemia vary with the mode of presentation.
Tularemia is caused by infection with the bacteria F tularensis. The 2 subspecies are A (tularensis) and B (holartica). In the western United States, type A infections may be less severe than type B infections.
| Catscratch Disease | Rhabdomyolysis |
| CBRNE - Plague | Salmonella Infection |
| Legionnaires Disease | Tick-Borne Diseases, Colorado |
| Lymphogranuloma Venereum | Tick-Borne Diseases, Introduction |
| Malaria | Tick-Borne Diseases, Lyme |
| Mononucleosis | Tick-Borne Diseases, Q Fever |
| Mumps | Tick-Borne Diseases, Rocky Mountain Spotted
Fever |
| Pharyngitis | Toxoplasmosis |
| Pneumonia, Viral |
Psittacosis
Brucellosis
Q fever
Legionella pneumonia
The goal of therapy is eradication of tularemia with antibiotics.
Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in context of the clinical setting. In treating tularemia, streptomycin is the drug of choice. Although less experience exists with other aminoglycosides, gentamicin also appears to be effective.
Although aminoglycosides are the drugs of choice, reports of patients who have responded well to fluoroquinolones (prior to tularemia being suspected) exist. In addition, in vitro susceptibility testing shows that the quinolones have great promise in treating tularemia. Thus, this class of drug may be an alternative in patients who cannot tolerate aminoglycosides. Also, many practitioners are using newer fluoroquinolones as monotherapy for community-acquired pneumonia.
Both levofloxacin and ciprofloxacin have been used clinically with success. In fact, in a large outbreak in Spain (142 cases), ciprofloxacin had the lowest treatment failure rate with the fewest side effects.3
While tetracycline and doxycycline have been used, both are bacteriostatic and not cidal for the organism. This is also true of chloramphenicol, relegating these 3 antibiotics to a third choice.
Aminoglycoside antibiotic recommended when therapeutic agents with less potential hazard are ineffective or contraindicated.
1-2 g IM divided bid for 7-14 d or until patient is afebrile for 5-7 d; not to exceed 2 g/d
20-40 mg/kg/d IM for 7-14 d or until patient is afebrile; not to exceed 0.75-1 g
Nephrotoxicity may be increased with aminoglycosides, cephalosporins, penicillins, amphotericin B, and loop diuretics
Documented hypersensitivity; non–dialysis-dependent renal insufficiency
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Narrow therapeutic index; not intended for long-term therapy; caution in renal failure not treated with dialysis; caution with myasthenia gravis, hypocalcemia, and conditions that depress neuromuscular transmission
Aminoglycoside used as an alternative to streptomycin. Less experience exists with this agent. Dosing regimens are numerous and adjusted based on creatinine clearance and changes in volume of distribution, as well as body space into which the agent must distribute. Follow each regimen by at least a trough level drawn on the third or fourth dose, 0.5 h before dosing; may draw a peak level 0.5 h after the 30-min infusion.
5 mg/kg/d IV/IM q6-8h
<5 years with normal renal function: 2.5 mg/kg/dose IV/IM q8h
>5 years: 1.5-2.5 mg/kg/dose IV/IM q8h or 6-7.5 mg/kg/d divided q8h; not to exceed 300 mg/d with adjustments for renal function prn
Coadministration with other aminoglycosides, cephalosporins, penicillins, and amphotericin B may increase nephrotoxicity; aminoglycosides enhance effects of neuromuscular blocking agents (prolonged respiratory depression may occur); coadministration with loop diuretics may increase auditory toxicity of aminoglycosides; possible irreversible hearing loss of varying degrees may occur (monitor regularly)
Documented hypersensitivity; non–dialysis-dependent renal insufficiency
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Narrow therapeutic index; not intended for long-term therapy; caution in renal failure not treated with dialysis, myasthenia gravis, hypocalcemia, and conditions that depress neuromuscular transmission; adjust dose in renal impairment
Third-line drug, tetracyclines being only bacteriostatic. Duration of treatment of <2 wk is associated with greater risk of relapse. Only potential advantage is its ability to cover other coexisting tick-borne pathogens. Inhibits bacterial protein synthesis by binding with 30S and possibly 50S ribosomal subunits of susceptible bacteria.
500 mg PO bid or 250 mg PO qid for 7-14 d
<9 years: Not recommended
>9 years: 10-20 mg/lb/d (25-50 mg/kg) PO divided qid
Bioavailability decreases with antacids containing aluminum, calcium, magnesium, iron, or bismuth subsalicylate; can decrease effects of oral contraceptives, causing breakthrough bleeding and increased risk of pregnancy; tetracyclines can increase hypoprothrombinemic effects of anticoagulants
Documented hypersensitivity; severe hepatic dysfunction
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Photosensitivity may occur with prolonged exposure to sunlight or tanning equipment; reduce dose in renal impairment; consider drug serum level determinations in prolonged therapy; tetracycline use during tooth development (last one half of pregnancy through age 8 y) can cause permanent discoloration of teeth; Fanconilike syndrome may occur with outdated tetracyclines
Insufficient data exist on use of chloramphenicol in tularemia. This agent is a distant third choice. Binds to 50S bacterial ribosomal subunit and interferes with or inhibits protein synthesis. Is effective against gram-negative and gram-positive bacteria.
50-100 mg/kg/d PO/IV divided q6h; not to exceed 4 g/d
50-75 mg/kg/d PO/IV divided q6h
Concurrently with barbiturates, chloramphenicol serum levels may decrease, while barbiturate levels may increase, causing toxicity; manifestations of hypoglycemia may occur with sulfonylureas; rifampin may reduce serum levels, presumably through hepatic enzyme induction; may increase effects of anticoagulants; may increase serum hydantoin levels, possibly resulting in toxicity; levels may be increased or decreased
Documented hypersensitivity
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Use only for indicated infections or as prophylaxis for bacterial infections; serious and fatal blood dyscrasias (aplastic anemia, hypoplastic anemia, thrombocytopenia, granulocytopenia) can occur; perform baseline and periodic blood studies approximately every 2 d during therapy; discontinue upon appearance of reticulocytopenia, leukopenia, thrombocytopenia, anemia, or findings attributable to chloramphenicol; adjust dose in liver or kidney dysfunction; caution in pregnancy at term or during labor because of potential toxic effects on fetus (gray syndrome)
May be a useful agent to treat tularemia.
500 mg PO qd
<18 years: Not recommended
>18 years: 250-500 mg PO qd
Antacids, iron salts, and zinc salts may reduce serum levels; administer antacids 2-4 h before or after taking fluoroquinolones; cimetidine may interfere with metabolism of fluoroquinolones; levofloxacin reduces therapeutic effects of phenytoin; probenecid may increase levofloxacin serum concentrations; may increase toxicity of theophylline, caffeine, cyclosporine, digoxin (monitor digoxin levels); may increase effects of anticoagulants (monitor PT)
Documented hypersensitivity
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
In prolonged therapy, periodically evaluate organ system functions (eg, renal, hepatic, hematopoietic); adjust dose in renal function impairment; superinfections may occur with prolonged or repeated antibiotic therapy
Fluoroquinolone that inhibits bacterial DNA synthesis and, consequently, growth by inhibiting DNA gyrase and topoisomerases, which are required for replication, transcription, and translation of genetic material. Quinolones have broad activity against gram-positive and gram-negative aerobic organisms. Has no activity against anaerobes. Continue treatment for at least 2 d (7-14 d typical) after signs and symptoms have disappeared.
Second DOC; in one study, was associated with lowest rate of treatment failure.
750 mg PO bid
<18 years: Not recommended
>18 years: Administer as in adults
Antacids, iron salts, and zinc salts may reduce serum levels; administer antacids 2-4 h before or after taking fluoroquinolones; cimetidine may interfere with metabolism of fluoroquinolones; reduces therapeutic effects of phenytoin; probenecid may increase ciprofloxacin serum concentrations; may increase toxicity of theophylline, caffeine, cyclosporine, and digoxin (monitor digoxin levels); may increase effects of anticoagulants (monitor PT)
Documented hypersensitivity
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Dosage adjustments (adult adjustments)
CrCl (mL/min) <10: 50% of PO or IV dose q12h
HD: 0.25-0.5 g PO or 0.2-0.4 g IV q12h
During peritoneal dialysis: 0.25-0.5 g PO or 0.2-0.4 g IV q8h
In prolonged therapy, perform periodic evaluations of organ system functions (eg, renal, hepatic, hematopoietic); adjust dose in renal function impairment; superinfections may occur with prolonged or repeated antibiotic therapy; not drug of first choice in pediatric patients because of increased incidence of adverse events compared to controls, including arthropathy; no data exist for dose for pediatric patients with renal impairment (ie, CrCl <50 mL/min)
Broad-spectrum, synthetically derived bacteriostatic antibiotic in tetracycline class. Almost completely absorbed, concentrates in bile, and is excreted in urine and feces as a biologically active metabolite in high concentrations. Inhibits protein synthesis and, thus, bacterial growth by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria. May block dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. Third-line drug; bacteriostatic.
100 mg PO/IV bid
<9 years: Not recommended
>9 years and <45 kg: 2-5 mg/kg (1-2 mg/lb) PO q12h
Bioavailability decreases with antacids containing aluminum, calcium, magnesium, iron, or bismuth subsalicylate; tetracyclines can increase hypoprothrombinemic effects of anticoagulants; tetracyclines can decrease effects of oral contraceptives, causing breakthrough bleeding and increased risk of pregnancy
Documented hypersensitivity; severe hepatic dysfunction
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Photosensitivity may occur with prolonged exposure to sunlight or tanning equipment; reduce dose in renal impairment; consider drug serum level determinations in prolonged therapy; tetracycline use during tooth development (last one half of pregnancy through age 8 y) can cause permanent discoloration of teeth; Fanconilike syndrome may occur with outdated tetracyclines
Complications of tularemia may include the following:
CDC. Tularemia associated with a hamster bite--Colorado, 2004. MMWR Morb Mortal Wkly Rep. Jan 7 2005;53(51):1202-3. [Medline].
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].
tick-borne disease, tularemia, Francisella tularensis, F tularensis, ulceroglandular, glandular, oculoglandular, oropharyngeal, pneumonic, typhoidal, rabbit fever, deer-fly fever, vector-borne disease, tularensis strain
Jonathan A Edlow, MD, Associate Professor of Medicine, Department of Emergency Medicine, Harvard Medical School; Vice Chairman, Department of Emergency Medicine, Beth Israel Deaconess Medical Center
Jonathan A Edlow, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.
Dan Danzl, MD, Chair, Department of Emergency Medicine, Professor, University of Louisville Hospital
Dan Danzl, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, Kentucky Medical Association, Society for Academic Emergency Medicine, and Wilderness Medical Society
Disclosure: Nothing to disclose.
Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment
Jon Mark Hirshon, MD, MPH, Associate Professor, Department of Emergency Medicine, University of Maryland School of Medicine
Jon Mark Hirshon, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Public Health Association, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.
John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.
Rick Kulkarni, MD, Assistant Professor of Surgery, Section of Emergency Medicine, Yale-New Haven Hospital
Rick Kulkarni, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: WebMD Salary Employment
© 1994-
by Medscape.
All Rights Reserved
(http://www.medscape.com/public/copyright)