Anthrax is an infection caused by the endospore-forming bacterium, Bacillus anthracis. These bacteria have been found naturally in soil samples from around the world, although they do not regularly occur.

Pathology

Anthrax is primarily a disease of domesticated and wild animals, particularly herbivorous animals. Humans become infected incidentally when brought into contact with diseased animals, which includes their flesh, bones, hides, hair and excrement.

In humans, anthrax is fairly rare; the risk of infection is about 1/100,000. The most common form of the disease in humans is cutaneous anthrax,which is usually acquired via injured skin or mucous membranes. A minor scratch or abrasion, usually on an exposed area of the face or neck or arms, is inoculated by spores from the soil or a contaminated animal or carcass. The spores germinate, vegetative cells multiply, and a characteristic lesion develops at the site. In severe cases, where the blood stream is eventually invaded, the disease may be fatal.

Another form of the disease, inhalation anthrax(woolsorters' disease), results most commonly from inhalation of spore-containing dust where animal hair or hides are being handled. The disease begins abruptly with high fever and chest pain. It progresses rapidly to a systemic hemorrhagic pathology and is often fatal if treatment cannot stop the invasive aspect of the infection.

Information on gastrointestinal anthrax will be added to this site at a later date.

The bacteria are able to invadetheir animal host because they are resistant to the host phagocytic response. During and after its invasion, the bacteria produce a toxin which has a lethal mode of activity. Death from anthrax in humans or animals frequently occurs suddenly andun expectedly. The level of the lethal toxin in the circulation increases rapidly quite late in the disease, and it closely parallels the concentration of organisms in the blood.

Treatment

Antibiotics should be given to unvaccinated individuals exposed to inhalation anthrax. Penicillin, tetracyclines and fluoroquinolones (Cipro) are effective if administered before the onset of lymphatic spreador septicemia, estimated to be about 24 hours. Antibiotic treatment is also known to lessen the severity of disease inindividuals who acquire anthrax through the skin. Inhalation anthrax was formerly thought to be nearly 100% fatal despite antibiotic treatment, particularly if treatmentis started after symptoms appear. A recent Army study resulted in successful treatment of monkeys with antibiotic therapy after being exposed to anthrax spores. The antibiotic therapy was begun one day after exposure.

Immunization

Currently, the anthrax vaccineis produced under contract to the Department of Defense, and only small quantities are made available as needed to civilians who are exposed to anthrax hazards in their work environment, such as veterinarians, lab workers and others. An attempt to immunize 2.5 million members of the military ended three years ago, but that policy is being reevaluated.Ifthe manufacturer receives approval from the FDA, vaccine production will resume.

The anthrax vaccine is a preparation of the protective antigen (a fraction of the toxin) recovered from the culture filtrate of an avirulent, nonencapsulated strain of Bacillus anthracis. Anthrax immunization consists of three subcutaneous injections given two weeks apart followed by three additional subcutaneous injections given at 6, 12, and 18 months. Annual booster injections of the vaccine are required to maintain a protective level of immunity.

Anthrax and Biological Warfare

The inhalation of anthrax sporescan lead to infection and disease. The possibility of creating aerosols containing anthrax spores has made B. anthracis a chosen weapon of bioterrorism. Iraq, Russia and as many as ten nations have the capability to load spores ofB. anthracis into weapons. Domestic terrorists may developmeans to distribute spores via mass attacks or small-scale attacks at a local level.

As an agent of biological warfare it is expected that a cloud of anthrax spores would be released at a strategic location to be inhaled by the individuals under attack. Spores of B. anthracis can be produced and stored in a dry form and remain viable for decades in storage or after release.

There is no evidence of person-to-person transmission of anthrax. Quarantine of affected individuals is not recommended. Anthrax spores may survive in the soil, water and on surfaces for many years. Spores can only be destroyed by steam sterilization or burning. The U.S. Navy Manual on Operational Medicine and Fleet Support, entitled Biological Warfare Defense Information Sheet states "Disinfection of contaminated articles may be accomplished using a 0.05% hypochlorite solution (1 tbps. bleach per gallon of water). Spore destruction requires steam sterilization." It has also been reported that boiling (100 degrees C) for 30 minutes kills endospores of B. anthracis.

An infection of local animal populations such as sheep and cattle could follow a biological attack with spores. Infected animals could then transmit the disease to humans through the cutaneous, gastrointestinal or inhalation routes  by spores from a contaminated animal, carcass or hide.

A segment of the U.S. military population has been vaccinated against anthrax. Anthrax vaccine consists of a series of six doses with yearly boosters. The first vaccine of the series must be given at least four weeks before exposure to the disease. This vaccine protects against anthrax that is acquired through the skin and it is believed that it would also be effective against inhaled spores in a biowarfare situation.

More Information?

Check these websites with anthrax articles and links.

www.bt.cdc.gov Public Health Preparedness and Response from CDC

www.cdc.gov/ncidod/dbmd/diseaseinfo/anthrax_g.htm Anthrax from CDC

www.anthrax.osd.mil Anthrax Vaccination Immunization Program fromDoD

www.abcnews.go.com ABC News search for "anthrax"

www.gsbs.utmb.edu/microbook/ch015.htmBacillus, by Peter C.B. Turnbull, Chapter 15 in Baron, Microbiology  - online edition.
 
 

Common Sense Points about anthrax and bioterrorism from www.bact.wisc.edu

1. Anthrax does not spread from person-to-person. The only way to get the inhalation form of the disease is to be exposed to large numbers of spores of the microbe.

2. Not much will kill these spores. They are resistant to microwaves, heat and many disinfectants.  If you burn your mail, that will work, but then you can't read that letter from Aunt Marge.

3. As far as getting dangerous mail, Use your head! First, you are not that important, why would terrorists send a package to you? Second, think about the logistics of sending out a large number of envelopes containing spores. Finally, getting spores in an envelope is not a grave threat. Anthrax spores need to be dispersed in the air withvery advanced equipment to become the dangerous form, pulmonary anthrax, that is lethal.

4. If you are still worried about it, think, don'tgive into blind fear. (1) Check the address, is it someone you know? If it is someone you know, no problem. (2) Check the post mark, where is it mailed from? (3) Is it a catalog? It is not likely that any retailer is going to send you something dangerous. (Note, glossy magazines will often put baby powder in between the pages to prevent them from sticking together. Keep that in mind.) If you are still worried and receive a suspicious package that does have a powder in it, report it to your local authorities and consult your physician. However, it will be very unlikely that you will receive one of these letters. Think about how many pieces of mail go out and how many people there are. Your chances are very low.

5. Things you can do to protect yourself from bioterrorism

a. Stop worrying

b. Stop smoking

c. Don't drink too much

d. Eat right

e. Exercise

f. Stop worrying

What? What does that have to do with bioterrorism? All of the above will build up your immune system. And besides, if you have to be scared into taking care of yourself, so be it.

6. Cutaneous anthrax only occurs when the spores encounter broken skin creating an easily recognized boil. Even then, the illness is rarely fatal.

7. Anthrax is easily treated with antibiotics if it is caught early enough. The only time one should be worried about this is if everyone around you is coming down with the flu at the same time.The government should be all over something like that and has a stock pile of antibiotics for such an occasion.

8. You should not try to get vaccinated nor buy antibiotics just in case.  First, your chances of contracting the disease are less than getting hit by lightning or winning the lottery, so you would be wasting your money. Second, you are depleting the stores of antibiotics that are available to treat people who may end up having the illness or, much more likely, some other illness where they need that antibiotic. Finally, they will go bad over time and not be effective anyway. No responsible physicianshould be filling prescriptions to people who have not been exposed to anthrax, "just in case".

9. The disease is caused by a bacterium, Bacillus anthracis, not a virus as reported by some news agencies. (By the way, some journalists are woefully ignorant of medicine and microbiology - be careful what you believe.) It is disappointing that certain news agencies are frankly feeding this frenzy in the name of ratings.

10. Is a biological attack possible? Sure anything is possible, but it is very, very unlikely. Could it happen. Yep. Is it worth worrying about? Nope.