Anthrax - Health - Lecture Slides, Slides of Public Health

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ANTHRAX

ANTHRAX

• - Etiologic agent: Bacillus anthracis Cohn 1875.
• - Large (8 x 1.2 mm) Gram positive, nonmotile,
• weakly hæmolytic; central spores, straight ends,
• encapsulated in vivo, produces long chains.
• - Pathogenic to herbivores, man, lab animals.
• - Habitat: Parasitic; persists in “cursed” fields.
• - Sporulation only in aerobic conditions.
• - Capsule antigen: poly D-glutamic acid g-peptide
• - Immunogenic protein toxin, edematizing, lethal.

(blue)

(red)

B. anthracis on Blood Agar

Inflammatory cells

Bacilli

Lymph node: necrosis, large bacilli

Natural history of Anthrax

• Encounter: defines disease type and outcome:
• Herbivores: Spores germinate, are eaten, and oral lesions or abrasions mediate → blood invasion
• Man: Spores in wool, hair, hide → skin or lung Vegetative forms in meat → bowel lesions
• Adhesion: spores or vegetative forms stick to tissues and multiply until they breach anatomic barriers:
• Invasion: first local, then lymphatic, and later
• Generalized infection → leading to death.

Malignant pustule

• Anthrax proper, Charbon
• In endemic areas, through contact with infected animals
• In industry, contact with hides, bones, wool, hair
• Occasionally, brushes, bone, ivory, clothes,etc.
• History in days: incubation of 3 to 4 days; then,
  • 1) Initial pimple or papule, single or multiple
  • 2) Vesicle ring around papule - initially, clear fluid
  • 3) Papule ulcerates, dries, becomes dark eschar
  • 3) Edema develops, becomes angry red
  • 3-on) No local pain, but local ganglia grow tender
  • 4) Eschar blackens, grows on vesicles, thickens

Black

eschar.

Redness

remains

Site of Malignant pustule

• Head: usually no complication
• Face: severe, superinfection; gangrene near eye
• Neck, breast or chest wall: massive edema, over thorax and sometimes involving scrotum
• Shoulders, arms: may be multiple, small lesions
• Forearms, fingers: atypical on palms
• General symptoms, fever, chills, depend on site.
• Weakness, hypotension are danger signs.

Very localized

thumb lesion.

Tough

subcutaneous

tissues limit

the lesion

Notice small finger ulcer,

but large edema and erythema

The forehead

lesion is minimal.

This could be due

to the localization

or to a previous

state of immunity