the ecology of anthrax spores: tough but not invincible

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The ecology of anthrax spores:Tough but not invincible

Sonja Brockmüller

Seminar presentation based on a paper by

Daniel C. Dragon and Robert P. Rennie

The Canadian Veterinary Journal

Volume 36, May 1995, pgs. 295 - 301(A copy of the paper is available in the course folder „Science News“ on OLAT)

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Short introduction to Anthrax:

Biologische Kampfsoffe sind wieder zu beachten

Artikel von Marc Deschka

in: Die Schwester / Der Pfleger 42, Jahrg 3/03

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Summary of possible bio-weapons

Category A Category B Category C

- Bacillus anthracis- Var iolavirus- Francisella tularensis- Botulinum-Toxin- Ebola-, Marburg-, Lassafever

- Coxiella burnetii- Brucella- Aophaviruses- Ricin-Toxin- Epsilon-Toxin of Clostridium perfringens- Staphylococcus Eterotoxin B

- Bipahvirus- Hantavirus- Multiresistant Tuberculosis- Haemoragic fever

spread by ticks

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Anthrax (Bacillus anthracis)• pulmonary-, cutaneous-

and gastrointestinal-anthrax

• Incubation time: First symptomes after 48 h (2-7 d)

• Therapie: Antibiotics (Ciprofloxazin, Doxycyclin, Penicilin)

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Cutaneous-anthrax

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Ecology of anthrax spores

• Spore integument respon-sible for the spores‘s surface hydrophobicity

• --> Protect inner spore

• Inside core less water

• Spores interact with their surroundings

• Vegetative cells need a nutrient rich environement

--> spore formation and lysis of vegetative cell

(See also BBOM 9th ed. Chapter 3.15)

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Ecology of anthrax spores

• Vegetative cells need a nutrient rich environement

--> spore formation and lysis of vegetative cell

• Endospore coat component: Dipicolinic acid (DPA)

-> ingestion by host macrophage cells is limited

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Ecology of anthrax spores

• Vegetative cells need a nutrient rich environement

-> spore formation and lysis of vegetative cells

• Endospore coat component: Dipicolinic acid (DPA)

-> ingestion by host macrophage cells is limited

• Endospores resist even prolonged exposure to chemical disinfectants, desiccation and extremes in pH, temperature, pressure, UV and ionizing radiation.

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Ecology of anthrax spores

• Vegetative cells need a nutrient rich environement

-> spore formation and lysis of vegetative cells

• Endospore coat component: Dipicolinic acid (DPA)

-> ingestion by host macrophage cells is limited

• Endospores resist even prolonged exposure to chemical disinfectants, desiccation and extremes in pH, temperature, pressure, UV and ionizing radiation.

• Global in its geographical distribution and endemic to many parts of Europe, Asia, Africa, North- and South America, Australia

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The ecology of anthrax spores: Tough but not invincible

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The ecology of anthrax spores: Tough but not invincible

Bison - Mortality in Northern Canada caused by Anthrax

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The ecology of anthrax spores: Tough but not invincible

• Dissemination of spores

• Weather and its consequences

• Soil quality

• Epidemiology of Anthrax with respect to Bisons

• Summary

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Dissemination of spores

• Scavengers and carnivores can act as carriers by dispersing ingested spores in their feces over large distances.

• Insects (mosquitoes, flies)

• Soil on the coat of wallowing animals (bison)

• Water and wind

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The ecology of anthrax spores: Tough but not invincible

• Dissemination of spores

• Weather and its consequences

• Soil quality

• Epidemiology of Anthrax with respect to Bisons

• Summary

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Weather and his consequence

• Anthrax epidemics generally occur during dry summer months following prolonged periods of heavy rain

• Water collects and concentrates the spores in „storage“ areas

• Water evaporates and allows the spores to be dispersed via the air

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The ecology of anthrax spores: Tough but not invincible

• Dissemination of spores

• Weather and its consequences

• Soil quality

• Epidemiology of Anthrax with respect to Bisons

• Summary

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Soil and its quality

• Outbreaks were most freqently associated with calcareous soils, rich in Ca2+ and nutrients

• High levels of calcium in the soil may buffer the internal supply of anthrax spores and greatly extend their viability

• “incubator area“ hypothesis: alkaline pH, high soil moisture, organic matter

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The ecology of anthrax spores: Tough but not invincible

• Dissemination of spores

• Weather and its consequences

• Soil quality

• Epidemiology of Anthrax with respect to Bisons

• Summary

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Epidemiology of anthrax with respect to bison

• Mortality among sexually mature males is higher than females and immature bisons.

• High temperatures, breeding activity, high levels of insect harassment, and population size of bisons -> immunity is weak -> low oral doses -> lethal infections

• Rutting agression-> stamping, wallowing -> dust clouds of aerosolized spores

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The ecology of anthrax spores: Tough but not invincible

• Dissemination of spores

• Weather and its consequences

• Soil quality

• Epidemiology of Anthrax with respect to Bisons

• Summary

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Summary

• Long lasting, highly resistant spores

• Correlation between disease and soil factors (likes calceouros soils)

• Vegetative cells are unlikely to survive outside a host