Conditions · Infectious and tropical diseases

Tularaemia !

Tularaemia is a bacterial infection caught from rabbits, rodents, ticks or flies that causes fever, a skin sore and swollen lymph nodes.

Updated 2026-11-01

Structures involved

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Microorganisms that cause it

Francisella tularensis

Why it happens

What it is

A zoonotic infection by Francisella tularensis. Its clinical form depends on how the bacteria enter: through the skin, eye, mouth or lungs. The most common form is a skin ulcer at the entry site with enlarged regional lymph nodes.

Who gets it

Tularaemia occurs mainly in the Northern Hemisphere: the United States, Canada, Europe and Asia, with a few reports from Central America. It is not known to be endemic in Colombia or the rest of South America, so local cases would point to travel or a laboratory or deliberate release. It is a classic exam topic because the organism is one of the recognised bioterrorism agents.

Causes

Francisella tularensis, a small, aerobic Gram-negative coccobacillus that survives inside macrophages
Reservoirs: rabbits, hares and rodents; vectors: ticks and deer flies
Entry through a bite, skinning or handling infected animals, contaminated water or food, or inhaled dust and aerosols
Very low infectious dose; no spread from person to person

Risk factors

Hunting, skinning or butchering rabbits and hares
Tick or deer fly bites in endemic areas
Farming, landscaping or mowing over animal carcasses (aerosols)
Laboratory work with cultures of the organism
Travel to endemic regions of North America, Europe or Asia

Pathophysiology

After entry the bacteria multiply locally and are carried to regional lymph nodes, where they live inside macrophages and avoid killing. Local necrosis forms an ulcer and enlarged, sometimes suppurating nodes. Spread through blood seeds the lungs, liver and spleen, producing granulomas with central necrosis. Inhaled organisms cause pneumonia with hilar node enlargement.

Classification

Ulceroglandular (most common): skin ulcer plus regional lymphadenopathy
Glandular: lymphadenopathy without an ulcer
Oculoglandular: conjunctivitis with preauricular nodes
Oropharyngeal: pharyngitis, mouth ulcers and neck nodes after contaminated food or water
Pneumonic: the most severe form, from inhalation or blood spread
Typhoidal: fever and systemic illness without a local focus

Symptoms and signs

Abrupt high fever, chills, headache, muscle aches and malaise a few days after exposure
Painful papule at the entry site that becomes a punched-out ulcer, often on a finger or hand
Large, tender lymph nodes draining the site (axilla, elbow, groin or neck), which may suppurate
Red, painful eye with swollen nodes in front of the ear in the oculoglandular form
Dry cough, chest pain and shortness of breath in the pneumonic form

Diagnosis

Clinical: Suspected from fever with an ulcer and regional lymphadenopathy after contact with rabbits, rodents, ticks or flies, or from atypical pneumonia with a compatible exposure. Treatment starts on suspicion.
Tests: Serology showing a fourfold rise in antibodies between acute and convalescent samples; PCR of ulcer swab, node aspirate or respiratory samples; culture on cysteine-enriched media. The laboratory must be warned in advance because the organism easily infects laboratory staff.
Imaging: Chest radiograph in the pneumonic form: patchy infiltrates, hilar lymph node enlargement and pleural effusion.

Differential diagnosis

Cat-scratch disease (bartonellosis)
Plague (more fulminant, bubo without an ulcer)
Staphylococcal or streptococcal lymphadenitis
Cutaneous anthrax (painless black eschar)
Lymphocutaneous sporotrichosis or mycobacterial infection

Goal of treatment

Start effective antibiotics early, prevent spread to the lungs and blood, drain suppurative nodes when needed and avoid laboratory exposures.

Treatment

Medical: An aminoglycoside (gentamicin or streptomycin) for severe disease; a fluoroquinolone (ciprofloxacin or levofloxacin) for mild to moderate disease; a tetracycline (doxycycline) is an alternative but not alone for severe or delayed cases.
Medical: Antibiotic prophylaxis with doxycycline or a fluoroquinolone after a laboratory or mass exposure.
Procedure: Drainage of suppurating lymph nodes that do not settle with antibiotics.
Follow-up: Kidney function and drug levels during aminoglycoside therapy; standard precautions only, because there is no person-to-person spread.

Complications

Suppuration of lymph nodes with chronic drainage
Pneumonia, lung abscess and pleural effusion
Sepsis, rhabdomyolysis and kidney failure
Meningitis, pericarditis or osteomyelitis (rare)

Prognosis

With prompt treatment mortality is low. Untreated pneumonic and typhoidal disease can be fatal, and node enlargement and fatigue may persist for weeks after cure.

Prevention

Gloves and care when handling or skinning wild animals
Tick and fly protection with clothing and repellents
Avoid mowing over dead animals and drinking untreated water in endemic areas
Biosafety precautions in laboratories

Test yourself

Think of the answer, then tap the question to see it.

Which animal exposure is classic for tularaemia?

Hunting or skinning rabbits or hares ("rabbit fever"), along with tick and deer fly bites.

What is the most common clinical form?

Ulceroglandular: a skin ulcer at the entry site with tender regional lymph nodes.

Why must the laboratory be told when tularaemia is suspected?

Francisella tularensis is highly infectious in culture and causes laboratory-acquired infections.

Which antibiotic class is preferred for severe tularaemia?

Aminoglycosides (gentamicin or streptomycin).

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Educational information, not medical advice. For any symptom, see a health professional.

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Representative model, for educational purposes only.

Skin highlighted on the Durgical 3D model