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Bioterrorist Agents: Tularemia

Bioterrorist Agents: Tularemia. CDC, AFIP. Diseases of Bioterrorist Potential Learning Objectives. Describe CDC-defined Category A agents Describe infection control and prophylactic measures in the event of an outbreak. Francisella Tularensis. Causative agent of tularemia

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Bioterrorist Agents: Tularemia

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  1. Bioterrorist Agents: Tularemia CDC, AFIP

  2. Diseases of Bioterrorist PotentialLearning Objectives • Describe CDC-defined Category A agents • Describe infection control and prophylactic measures in the event of an outbreak

  3. Francisella Tularensis • Causative agent of tularemia • Non-motile, non-spore-forming gram negative cocco-bacillus found in diverse animal hosts • Studied by U.S. and others as potential BW weapon • Resistant to freezing temperatures, sensitive to heat and disinfectants

  4. Francisella TularensisEpidemiology • Humans infected by various modes: • Handling contaminated animal tissues or fluids • Bite of infected deer flies, mosquitoes, or ticks • Direct contact with or ingestion of contaminated water, food or soil • Inhalation of infective aerosols (most likely BT route) • About 200 cases of tularemia/year in U.S. • Most in South-Central and Western states • Most in rural areas • Majority of cases in summer

  5. Francisella TularensisEpidemiology • Low infectious dose: 10-50 organisms produce disease • Incubation period: probably 3-5 days following aerosol exposure (range 1-21 days) • Case fatality rate • Treated: <1-3% • Untreated: 30-60% (pneumonic), 5% (ulceroglandular) • Recovery followed by permanent immunity • No person-to-person transmission

  6. Tularemia: Case Definition • An illness characterized by several distinct forms, including the following • Ulceroglandular (cutaneous ulcer with regional lymphadenopathy) • Glandular (regional lymphadenopathy with no ulcer) • Oculoglandular (conjunctivitis with preauricular lymphadenopathy) • Oropharyngeal (stomatitis or pharyngitis or tonsillitis & cervical adenopath) MMWR 1997;46(RR-10)

  7. Tularemia: Case definition, cont. • An illness characterized by several distinct forms, including the following • Intestinal (intestinal pain, vomiting, diarrhea) • Pneumonic* (primary pleuropulmonary disease) • Typhoidal (febrile illness w/o early localizing signs & symptoms • Clinical diagnosis supported by evidence or history of a tick or deerfly bite, exposure to tissues of a mammalian host of F. tularensis or exposure to potentially contaminated water. MMWR 1997;46(RR-10)

  8. Tularemia: Case Definition, cont. • Laboratory criteria for diagnosis • Presumptive: • Elevated serum antibody titer(s) to F. tularensis antigen (w/o documented 4-fold or greater change) in a patient with no history of tularemia vaccination OR • Detection of F. tularensis in a clinical specimen by fluorescent assay • Confirmatory: • Isolation of F. tularensis in a clinical specimen OR • 4-fold or greater change in serum antibody titer to F. tularensis antigen MMWR 1997;46(RR-10)

  9. Tularemia: Case Classification • Probable: Clinically compatible with lab results indicative of a presumptive infection • Confirmed: Clinically compatible with confirmatory lab results MMWR 1997;46(RR-10)

  10. Ulceroglandular TularemiaClinical Features • 75-85% of naturally occurring cases • General symptoms – high fever, malaise, muscle aches, headache, chills & rigors, sore throat • Cutaneous papule appears at inoculation site concurrent with generalized symptoms • Papule --> pustule --> tender indolent ulcer with or without eschar • Tender regional lymphadenopathy

  11. Ulceroglandular Tularemia

  12. Pneumonic TularemiaClinical Features • Initial clinical picture: systemic illness with prominent signs of respiratory disease • Abrupt onset fever, chills, headaches, muscle aches, non-productive cough, sore throat • Nausea, vomiting, diarrhea in some cases • Mortality 30% untreated; < 10% treated

  13. Tularemia Treatment & Prophylaxis • Vaccine: live attenuated vaccine under FDA review – availability uncertain • For known aerosol exposures, 14d oral antibiotics recommended • If covert attack, observe for development of fever for 14 days and treat with antibiotics if febrile • Post-exposure antibiotics – most effective when given w/in 24 hours of exposure

  14. TularemiaInfection Control • Standard precautions • No patient isolation necessary due to lack of human-to-human transmission • Alert lab of suspicion for tularemia

  15. TularemiaSummary of Key Points • In naturally occurring tularemia, infection virtually always occurs in a rural setting. Infection in an urban setting with no known risk factors or contact with infected animals suggests a possible deliberate source. • Tularemia is not transmitted person to person.

  16. TularemiaSummary of Key Points • The most likely presentations of tularemia in a BT attack are pneumonic and typhoidal disease, as opposed to cutaneous disease in naturally occurring cases. • Tularemia can be treated and prevented with antibiotics.

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