AerobicEndospore formersBacillus

Epidemiology of Anthrax

Disease/bacterial factors

Transmission

Who is at risk

Geography/ season

Incidence

Modes of control

Bacillus

Gram positive

Spore formers

Obligate aerobe

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B. anthracis colony

Medusa head

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Bacillus Spore

Bacillus pathogens

B. anthracis
- anthrax

B. subtilis
- eye infections

B. cereus
- 2 forms offood poisoning

Bacillus spp
- wounds, chronic ulcers, dust and soil

B. alvei
- Foulbrood
- fatal disease of bees

Anthrax

Mainly cattle, sheep, goats, horses

Man infected by contact with diseased products

Human transmission possible
- Outbreak in Gambia

Anthrax: Incidence

Humans incidence dropping steadily
- 100,000 globally /year
- 1-2 /year North America

Endemic in animals in some states
- California, Louisiana, Mississippi, Arkansas, Texas, Dakota, Nebraska

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Forms of Anthrax

Cutaneous
- 95% of human cases

Intestinal
- common in cattle
- grazing

Pulmonary
- now rare

Anthrax: Wool sorter’s Disease

Stevadore’s Disease

Anthrax: Eschar

Appears on exposed parts of body

Anthrax: Eschar

spore germinates at site of entry

black, malignant

painless

May heal spontaneously

septicemia
- 20% mortality

Evolution of an Anthrax Eschar

Evolution of an Eschar

Pulmonary Anthrax

Now rare
- mortality approaches 10%

“Wool Sorters Disease”
- industrial mills 19th century
- Pneumonia

survives phagocytosis
- lymph nodes
- septicemia

Anthrax: Pathogenesis

Capsules
- antiphagocytic
- protein capsule

Toxin

Exotoxin

pH 7.4, stabilized by serum & bicarbonate

3 sub components

Anthrax toxin

Edema factor (EF)
- 88.9 Kda calmodulin dependent
- adenylate cyclase

Lethal factor (LF)
- 90.2 Kda
- zinc metalloprotease

Protective antigen (PA)
- 82.7 Kda
- 20KDa fragment hyrdolyzed

Action of Anthrax Toxin

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The End

Bacillus cereus Food Poisoning

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