Anthrax- A Zoonotic Disease of Biblical Proportions

History

Bacillus anthracis is the oldest known disease of grazing animals and is thought to be the cause of two of the plagues mentioned in the Old Testament(diseased livestock and boils).The infectious agent was discovered by Koch in 1877(1^st agent identified using his postulates). The first vaccine is credited to Louis Pasteur in 1877, however it was actually prepared a year earlier by Greenfield in England.

Infectious agent

Bacillus anthracis

-          Forms dominant spores

       - able to survive harsh conditions for decades/centuries

       - lots of evidence they are resistant

              - recovered spores from 200 year old archaeological remains

              - resistant to microwave irradiation at 100C for 30 min

Infection Cycle

Infection

1.      Uptake by inhalation

2.      Spores end up in alveoli of the lungs

3.      Picked up by macrophages

4.      Transported to lymph nodes

5.      Spores germinate in lymph nodes

6.      Multiply and lyse macrophages

7.      Bacilli in bloodstream release lethal factor, edema factor and protective antigen

Here is a link to a good clip about the mechanisms of anthrax:

      http://www.youtube.com/watch?v=7LRGT098lxc&feature=related

3 Forms of Human Disease

Pulmonary

-          Historically 92% mortality rate

-          With early treatment(before toxins released) 45% mortality

-          Initial symptoms mild

          -similar to upper respiratory infection

Gastrointestinal

-          Primary source: eating infected meat

-issue in developing countries

      -  25-60% treatable

            - difficult to identify quickly

Cutaneous

-          Most common source of infection

-          Boil-like lesions, itchy but not very painful

-          Primary source: contact with infected carcasses, contaminated wool/hides

-          Mortality rate(untreated)-20%

Recent Human Anthrax Outbreaks

-          1978-1980- Zimbabwe-

      -10 000 human cases; 151 deaths

-          1979- Sverdlovsk, Russia

       -involved people and livestock

       - traced to release of spores into the air surrounding a biological weapons                                                                                           factory

       - 200 dead?

      -     2001- USA

                   - bioterrorist cases of anthrax in postal service

                   - 22 infected; 5 deaths

      - 2010- Scotland(England and Germany)

                - anthrax-laced heroin

                - 51 cases(known); 14+ dead

Treatment

-          Effective decontamination of: People-antimicrobial soap and water

                                             Wastewater- treat with bleach

                                             Clothing-boil for 30 min.

-          Early antibiotic treatment crucial

-Penicillin, Streptomycin effective at killing bacterium

- Not effective against toxins