lec 59 60 zoonosis Flashcards
Anthrax Bacillus Anthracis general characteristics?
Gram positive rods, aerobic, spore forming, appear in long chains, pairs or single cells
Unique characteristic of Anthrax Bacillus Anthracis?
Squared-ends “boxcar” in culture and eschar a cectoric ulcer in cutaneous (direct inoculation) anthrax
Spores of Anthrax Bacillus Anthracis
Culture and soil, remain viable for decades
Not observed in clinical samples, Easy to grow in the lab
Virulence Factors Anthrax Bacillus Anthracis
Protein Capsule, antiphagocytic
Poly-D-glutamic acid, not produced in culture
2 Toxins
2 toxins of Anthrax Bacillus Anthracis
Protective antigen, lethal factor, edema factor combine into two different toxins
Lethal toxin
disrupts normal cellular signaling events cell death, inflammation, and tissue damage
Edema toxin
adenylate cyclase cAMP levels ion/water efflux edema
Responsible for most of disease pathology
AnthraxBacillus anthracis pathogenesis
Spores either inoculated, ingested, or inhaled
Spores germinate into vegetative cells that produce toxin
pathogenesis mechanism of anthrax bacillus anthracis involving Protective antigen
PA Binds to cellular receptors on numerous tissues and cell types
Is activated by cleavage by host cell enzymes and forms a multimeric complex on the host cell surface
LF and / or EF bind to this complex and are internalized by the cell
Epidemiology of AnthraxBacillus anthracis
Worldwide distribution
Primarily a disease of herbivores
Cattle, sheep, goats, horses
Animals become infected while grazing in contaminated pastures
Considered endemic in the United States
1 or 2 cases annually
Modern agricultural practices limit its transmission / acquisition (wearing gloves etc)
What are the principle reservoirs of AnthraxBacillus anthracis
Animals (Cattle, sheep, goats, horses) and soil
impact anthrax vaccine?
Animal vaccine made huge impact ,human one hardly any
Anthrax bioterism attack 2001
22 cases (11 inhalation, 11 cutaneous) in 4 states and DC 5 deaths, all inhalation
B. anthracis spores sent through U.S. mail
Most exposures mail sorting facilities and sites where mail was opened
Three types of infections in humans with antrax baccilus anthracis
Inoculation, inhaklation, ingestion
Inoculation of anthrax bacillus anthracis
Cutaneous anthrax (most common)
Direct inoculation of spores onto existing open cuts / wounds
Spores from soil, animal furs, hides, wool or skin
Which groups are at highest risk for inoculartion (cuteneous) anthrax?
Butchers, slaughterhouse workers at risk when processing infected animals
Inhalation anthrax
Inhalation of spores, uncommon
Called “wool-sorters disease”; historically occurred in individuals processing wool from sheep and goats
What is the most common route of transmissin of anthrax in bioterrist attacks?
Inhalation
Ingestion Anthrax
Gastrointestinal anthrax (rare) Infection by ingestion of contaminated meat
incubation of cutaneous anthrax
2-12 days
symptoms (signs) of cutaneous anthrax
Small red papule vesicle necrotic ulcer (eschar) with black center
Described as painless
May be accompanied by lymph node swelling
Lesions may resolve over several weeks
fatality rate of cutaneous anthrax
Antibiotic treatment: < 1%
Without treatment: 5 – 20%
Incubation of inhalation anthrax
days to weeks to months
Signs and symptoms of inhalation anthrax
Initially presentation is non-specific
Non-productive cough, shortness of breath, myalgia, fatigue, and fever
Second stage presentation
Fever, drenching sweats, extreme dyspnea, cyanosis, lymphadenopathy, shock, and in most cases death
Pneumonia rarely develops
Meningeal symptoms in half of cases
mortality rate of inhalation anthrax
Virtually 100% without treatment in 3 days
45 to 75% even with treatment
signs/symptoms of gastrointestinal anthrax
Upper GI involvement includes oro-pharyngeal ulcerations (tongue, tonsils, esophagus) with cervical lymphadenopathy and fever
Intestinal involvement includes abdominal pain, nausea, fever, bloody vomit, bloody diarrhea
May progress to sepsis
