Francisella Flashcards
What diseases does Francisella spp. cause?
rabbit fever
deer fly fever
Can Francisella tularensis be used as a biological weapon?
yes
What subtype is F. tularensis subsp. tularensis? Where is it found?
highly virulent type A
North America
What subtype is F. tularensis subsp. holarctica? Where is it found?
less vireulent type B
Eurasia and North America
What subtype is F. tularensis subsp. mediasiatica? Where is it found?
type C - similar virulence to subsp. holarctica
Asia
Describe the general characteristics of Francisella tularensis
gram neg coccobacillary rods, can be pleomorphic
non-motile
facultative intracellular pathogen
obligate aerobe
Does F. tularensis gram stain well?
no - gram stains poorly due to high lipid content
Does Francisella tularensis require supplementation in media for culture?
yes - needs cysteine
Does F. tularensis grow on MAC?
NO
F. tularensis oxidase and catalase reactions
oxidase neg
weakly catalase pos
What are the vectors of F. tularensis?
ticks, biting flies, mosquitos
Reservoirs of F. tularensis
rodents
lagomorphs
galliform birds
deer
Domestic hosts of F. tularensis
sheep
cats
dogs - rarely show clinical signs, may be a reservoir host
horses
pigs
What other species can be infected by F. tularensis?
birds, amphibians, fish, reptiles
Transmission of F. tularensis
via skin abrasions, bites, scratches
arthropod bites
inhalation
ingestion
conjunctiva
Clinical manifestations of F. tularensis infections
chronic granulomatous lesions
subclinical infection s
fulminating disease - immunocompromised individuals
Pathogenesis of F. tularensis
main target is macrophages
infect hepatocytes, epithelial and endothelial cells
inhibits phagosome/lysosome fusion
Virulence of F. tularensis
Francisella Pathogenicity Island - type IV secretory system
two copies in virulent strains
one copy in less virulent strains
Clinical signs of F. tularensis in lagomorphs and rodents
animals often found dead
fever, ulcers, lymphadenopathy, abscesses, weakness and death 8-14 days
Clinical signs of F. tularensis in sheep
commonly infected
outbreak during peak tick season
fever, respiratory distrss, rigid gait, PD, diarrhea
mortality in young sheep
abortion
Clinical signs of F. tularensis in horses
associated with severe tick infestation
fever, unsteady gait, dyspnea, depression
Clinical signs of F. tularensis in cats
more susceptible than dogs
non-specific clinical signs
can quickly progress to death
fever, lethargy, inappetence, poor BCS, icterus, vomiting, dehydration, lyphadenopathy, hepatomegaly, splenomegaly, oral and lingual ulcers
Clinical signs of F. tularensis in dogs
relatively resistant
occasional disease in young adult dogs
fever, inappetence, peripheral lymphadenopathy
Diagnosis of F. tularensis from clinical specimens
blood for serology
scrapings from ulcers
lymph node aspirates
respiratory secretions
biopsy material or post-mortem samples
direct examination, giemsa stain, direct fluorescent antibody test
paired sera testing
ELISA
isolation
PCR
MALDI-TOF
Appearance of F. tularensis on culture
small, grey mucoid colonies
narrow zone of incomplete hemolysis
Treatment of F. tularensis
antibiotics
resistant to beta lactams (produce beta-lactamases)
Control of F. tularensis
ectoparasite control
prevent contamination
prevent dogs and cats from hunting wildlife species
Is there a vaccination available for F. tularensis?
NO
Is F. tularensis a notafiable disease?
YES
