Francisella Tularensis

Causes rabbit fever and deerfly fever.

Characteristics/Epidemiology

Primarily animal pathogen

Wild/domestic mammals, birds, and pets

 

 

Pathogenesis/Transmission

Transmission

Transmission - direct contact with infected tissues or bite of infected vector.

Transmission vector - blood-sucking/biting arthropods

Ticks also serve as reservoirs, can pass bacteria via their egg to progeny.

 

 

 

 

 

 

 

 

 

Survives in macrophages as well as other types of cells

 

 

Clinical significance

Tularemia - range from mild to fatal

Onset usually abrupt

Symptoms - mostly flu-like

• Chills and fever
• Headache
• Malaise
• Anorexia
• Occasionally respiratory/gastrointestinal symptoms

Ulceroglandular tularemia

Most common form

Lymphadenopathy is characteristic

Direct cutaneous inoculation

Multiplies locally for 3-5 days.

Produces a papule that ulcerates after days, may persist for weeks.

Spread from local lesion to regional lymph nodes

   -> enlarged, tender nodes with possible suppuration

   -> via lymphatic system - multi-system spread

Glandular tularemia

Tularemia with lymphadenopathy without evidence of ulceration

Oculoglandular tularemia

Gain entry by conjunctiva

Pharyngeal tularemia

Entry through pharynx - severe sore throat

Pneumonic tularemia

Direct inhalation or by hematogenous dissemination

 

 

Laboratory identification

Feature

Pleomorphic

Lipid-rich capsule

Facultative intracellular parasite

Strictly aerobic

Fastidious

Diagnostic test

Culture - require sulfhydryl e.g. cysteine, and dangerous due to lab transmission

Diagnosis relies mostly on clinical history and possible exposure

Serology test - by agglutination or ELISA possible.

Treatment

First line: Gentamicin or streptomycin

 

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Bibliography:

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