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Tularemia

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may have multiple cutaneous lesions (musk-rat associated outbreak in Vermont) glandular (15-20%) like ulceroglandular without cutaneous lesions. oculoglandular (1-4 ... – PowerPoint PPT presentation

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Title: Tularemia


1
Tularemia
  • Agent
  • Francisella tularensis
  • Named for Sir Edward Frances (did original work
    on disease) and Tulare, CA (where disease agent
    was first isolated)
  • Other names of human disease
  • rabbit fever
  • deer-fly fever

2
Tularemia
  • Microbiological features
  • Gram-negative, coccobacillus
  • non-motile, unencapsulated
  • Two subtypes differ based on virulence
  • Type A (biogroup tularensis)
  • highly virulent for humans and rabbits
  • found in North America
  • Type B (biogroup palearctica)
  • less virulent for humans, found in aqautic
    animals
  • found in Asia and Europe

3
Tularemia
  • Microbiological features
  • no growth on routine media (requires cysteine or
    cystine)
  • special culture media - thioglycolate,
    glucose-cysteine blood agar, chocolate agar
  • addition of CO2 may enhance growth

4
Tularemia
  • Pathogenesis
  • intracellular growth, therefore cell-mediated
    immunity directed against protein antigens is
    responsible for resistance and recovery
  • infectious dose depends on site of entry
  • few organisms (10-50) required for intradermal
    injection or inhalation
  • large number (108) if ingested

5
Tularemia
  • Epidemiology
  • Occurrence
  • common throughout North America
  • more common in US prior to 1950, steadily
    declining incidence since 1965
  • Incidence 0.05-0.15/100,000
  • 50 of cases from AR, OK, MO
  • over 75 in men
  • more common in gt30 years of age
  • recent studies indicate pediatric population can
    represent up to 28 of cases in certain areas

6
Tularemia
  • Epidemiology
  • Route of transmission
  • bite of arthropod vector
  • inoculation of skin, mucous membranes with
    contaminated water, blood, tissue
  • ingestion of insufficiently cooked meat or
    contaminated water
  • inhalation of dust from soil, grain, hay
  • animal bite (rare) from animal eating on infected
    carcass

7
Tularemia
  • Vectors
  • Amblyomma americanum - lone star tick
  • Dermacentor variabilis - American dog tick
  • D. andersoni - American wood tick
  • Chrysops discalis - deer fly
  • Aedes cinereus (Sweden)

8
Tularemia
  • Clinical features
  • Incubation period
  • relates to virulence, size of inoculum, location
  • 1 - 14 days (3-5 days average)
  • Symptoms based on six classic forms of disease
  • ulceroglandular
  • glandular
  • oculoglandular
  • oropharyngeal
  • typhoidal
  • pneumonic

9
Tularemia
  • Clinical features
  • Symptoms
  • abrupt onset of fever, chills, headache,
    anorexia, fatigue
  • ulceroglandular (50-75)
  • enlarging, painful lymphadenopathy
  • large red papule that becomes ulcerative and
    tender
  • may have multiple cutaneous lesions (musk-rat
    associated outbreak in Vermont)
  • glandular (15-20)
  • like ulceroglandular without cutaneous lesions
  • oculoglandular (1-4)
  • edematous, inflamed eyelid with ulceration of
    conjunctiva and sclera

10
Tularemia
  • Clinical features
  • Symptoms
  • oropharyngeal (4-18)
  • pharyngitis ranging from mild to strep or
    mono-like
  • local lymphadenopathy
  • typhoidal (8-18)
  • acute bacteremia
  • skin manifestations (exanthems, erythema nodosum)
  • diarrhea (bloody)
  • pulmonary - infiltrates and pleural effusion can
    be seen with other forms of disease

11
Tularemia
Lymphoglandular lesion - eschar
12
Tularemia
Lymphoglandular lesion - ulcer
13
Tularemia
Lymphoglandular lesion - necrotic lymph node
14
Tularemia
Typhoid form - x-ray of pulmonary inflitrates
15
Tularemia
Typhoid form - pulmonary inflitrates (CT scan)
16
Tularemia
Oculoglandular lesion
17
Tularemia
Lesions in liver from infected rabbit (white
spotted liver)
18
Tularemia
  • Clinical features
  • Diagnosis
  • accurate history, with attention to epidemiologic
    features
  • culture and identification
  • type A ferment glycerol and converts citrulline
    to ornithine
  • agglutination test - most commonly available
  • can cross react with Brucella
  • agglutinating antibodies with first couple of
    weeks, peak in four weeks
  • a single titer gt1160 or four-fold rise in titer
  • titers may remain elevated for 10 years
  • PCR useful, but only available for research
    purposes

19
Tularemia
  • Clinical features
  • Treatment
  • streptomycin - drug of choice but limited supply
    in some areas
  • gentamycin - when streptomycin not available
  • doxycycline - 21 days preferred
  • Case fatality ratio
  • up to 60- inhaled form leading to pneumonia and
    septicemia (typhoidal form) if untreated

20
Tularemia
  • Prevention and control
  • education
  • avoid exposure
  • proper handling during skinning, processing
    protective gloves, eye wear
  • tick (and other arthropod) control
  • proper cooking of meat
  • live attenuated vaccines for certain occupations
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