Test 2-• Francisella Flashcards
Francisella
- F. tularensis
- Subspecies mediasiatica
- Subspecies holartica
- Subspecies tularensis
- (Subspecies novicida)
- (F. philomiragia)
- (F.noatunensis) • F.novicida
The genus Francisella
- Gram negative
- Small
- Pleomorphic, coccoid, rod
- Non-motile
- Obligate aerobic
• Very fastidious growth
- Rich media
- Chocolate agar
-Thayer-Martinagar
• Supplementary cysteine
- CO2 • 37oC
- 2 days
SPREAD BY RABBITS
Francisella tularensis
• Reportable disease
• Highly contagious
• Last Belgian case: caught the rabbit and opened it
- Prairie dogs from the US
- Wide range of animals
Francisella tularensis
Epidemiology
Reservoir
• Infected lagomorphs-RABBITS
- Rodents
- Amoeba
Transmission
• Ticks, mosquito’s, flies
- Contaminated waters
- Ingestion of infected pray
Human infections
• Contact wild life-percutaneous
• Inhalation
• Bite of hematophagus insects
• Contaminated water (large outbreak in Sweden)-ingestion
Francisella tularensis
Virulence factors
• Capsule
- Anti-complement
- Endotoxin (LPS)
- Factors that promote intracellular survival in phagocytes (on the Francisella pathogenicity island)
Francisella tularensis
Spread
Disease of the Northern hemisphere
- F. tularensis subsp. tularensis– North America
- F. tularensis subsp. holarctica — Europe
- F. tularensis subsp. mediasiatica –Central Asia
Francisella tularensis
Pathogenesis
• Primary pathogen of lagomorphs and rodents
- Wild life disease
- Reservoirs
- Always a systemic phase with multi-organ failure
- Facultative intracellular (mainly macrophages)
Francisella tularensis
Clinical presentation
- Note: rare disease
- Symptoms are rarely seen (succumb fast)
• Mainly liver, spleen, lungs affected
Francisella tularensis
Clinical presentation humans
Depend on the mode of transmission and the virulence of the strain
- Virulence of strain
- Type B (ss holartica)milder disease
- TypeA (ss tularensis) more virulent- AMERICAN
- Identical symptoms but≠intensity
- Mode of transmission
Francisella tularensis
Clinical presentation humans
Mode of transmission
Ulceroglandular
- Ulcerated cutaneous lesion with lymphadenopathy in drainage zone
- Bite of infected hematophagus insect (tick, mosquito,…)
- Direct contact infected animal & skin damage
Glandular
-Cfr. above but without skin lesion
- *Oculoglandular**
- Infection through the conjunctiva
- Conjunctivitis
Francisella tularensis
Clinical presentation humans
• Oro-pharyngeal
Pharyngitis and/or gastro enteritis
Ingestion of contaminated food or water
• Respiratory (pneumonic) • Inhalation
- Typhoid
- Systemic disease
Francisella tularensis
Diagnosis
- Isolation: BSL3
- Serology (commonly used)
- Agglutination
- Micro-agglutination • ELISA
- PCR & RT-PCR
Francisella tularensis
Treatment and control
Antimicrobials
• Eg. aminoglycosides, fluoroquinolones, tetracyclines
Prevention & control
- Ticks
- Elimination from contaminated waters
- Wildlife
