Bacteria

» Jump to: Anthrax — Plague

Bacteria are microscopic, single-celled, prokaryotic organisms that carry out a wide range of biochemical processes. Many have beneficial effects such as enriching the surrounding soil. However, some may cause disease by invading body tissue or by producing harmful toxins. Bacteria cause strep throat, dysentary, undulant fever, cholera, diphtheria, Lyme disease, salmonella, pulmonary tuberculosis, and the bubonic plague.

Anthrax

Anthrax in a Monkey Yellow: Rod-shaped bacteria Red: Red blood cell

Anthrax is caused by the bacterium named Bacillus anthracis. It may be transmitted from animals to humans. Death from anthrax results from pneumonia, infections, and organ failure. Bacillus anthracis forms spores, protective cells with a hard coating, which can survive extreme temperatures for years. Spores remain in a dormant state until conditions become right. When the spores reach an environment that is warm and moist, such as human or animal lungs, they become active.

Inhaling a few thousand anthrax spores (less than it takes to cover a pinhead) can result in death unless the infected person is quickly treated with antibiotics.

The US Defense Department considers anthrax to be the top choice for a biological weapon in germ warfare for the following reasons:

• Anthrax is almost always lethal if not treated early
• Only a basic knowledge of biology is necessary to produce large quantities of spores
• Spores can be stored for decades without losing their effectiveness
• Spores can be sprayed in the air by missiles, rockets, artiller, aerosol bombs, and sprayers

Anthrax Causes Disease and Contamination
In 1943, Great Britain released anthrax on the island of Gruinard off the northwest coast of Scotland as part of a government test. The aim was to discern how much anthrax would be required for attacks on cities. In spite of many efforts to clean up Gruinard, the island was not considered safe for unprotected visitors until the 1990's.

2001 Anthrax Attacks

Letter sent to Senator Tom Daschle containing anthrax

In the weeks following the September 11 terrorist attacks, letters containing anthrax bacteria were mailed to several news offices and two US Senators. A total of five people were killed. The government still has not caught the culprit behind the attacks.

Letters postmarked September 18, 2001 were emailed to ABC News, CBS News, NBC News, the National Inquirer and the New York Post. Only the New York Post and NBC news letters were actually found. Two more letters postmarked October 9, 2001 were addressed to Tom Daschle (D-SD) and Patrick Leahy (D-VT), both Democratic Senators. The material in these letters was much more potent than the anthrax in the first set of letters. They contained approximately one gram of powder containing highly refined anthrax spores.

The letter to Senator Daschle was opened by an aide on October 15, where the government mail service was promptly shut down. The unopened Leahy letter was discovered in an impounded mail bag on November 16. It has been misdirected to the Sterly, Virginia due to an unclear Zip code. David Hose, a postal worker there, contracted inhalational anthrax.

Forms of Anthrax

There are three different forms of anthrax and each has different signs and symptoms:

1. Cutaneous anthrax:

This form affects the skin when the spores enter a cut, blister or abrasion on the skin. It begins with an itchy bump which soon develops into an open sore with a black center. It is the most common form of anthrax and accounts for 95 percent of the cases.

Inhalational Anthrax

2. Gastrointestinal anthrax:

This form is caused by eating undercooked meat from an infected animal. It creates sores similar in cutaneous form, but is much more fatal. Nonetheless, this form of anthrax is not likely to be delivered by biological weapons.

3. Inhalation (pulmonary) anthrax:

This form is caused by inhaling anthrax spores. Initial signs and symptoms include sore throat, mild fever, fatigue, and muscle aches--very much like the flu. Soon afterwards, however, the disease destroys lung tissue and may spread to the brain, causing meningitis. Inhalation anthrax is much more fatal compared to cutaneous anthrax.

Interesting Fact:
In Sverdiovsk, Russia, more than 60 people died when a bioweapons plant accidentally released anthrax spores and caused an outbreak of inhalational anthrax in 1979.

Particle Size

A mass anthrax attack requires the creation of aerosol particles of 1.5 to 5 micrometers. Larger than this, the aerosol would be filtered out by the respiratory system. Smaller and the aerosol would be inhaled and exhaled. At this size, nonconductive powders clump and cling together because of electrostatic charges, which hinders dispersion. Thus, the material must be treated with silica to insulate and discharge the charges. The aerosol must be delivered so that rain and sun will not rot it, and yet still allow for infection of the human lung. There are other technological difficulties as well.

Plague

Yersinia pestis Stained fluorescent (DFA)

The plague is a highly infectious disease caused by the bacterium called Yersinia pestis. The bacterium is usually found in rodents, or rats, and is spread through flea bites. In the 14th century, the plague wiped out as many as 20 to 30 million people in Europe--approximately a third of the population. In addition, an estimated 13 million people in China died from the plague.

Human infection occurs when a person is bitten by a rat flea that has fed on an infected rodent. In this way, infected blood carrying Yersinia pestis is transported from organism to organism through rats and fleas.

There are several different types of plague, including:

Bubonic

Bubonic plague is the most common type of plague in humans. This was the type of plague that wiped out over 30 million people in the 14th century. Bubonic plague occurs when Yersinia pestis causes an inflammation of the lymph nodes, making them tender and swollen.

 

Pneumonic

Pneumonic plague would be the most probable plague with which humans would be infected in the case of bioterrorism. Pneumonic plague spread very rapidly (within two days) and causes headache and chest pain, followed by respiratory failure. It is the second most common form of plague.

 

Septicemic

Septicemic plague occurs when Yersinia pestis multiples in blood. Septicemic plague is associated with hunting and skinning of animals, but it can also occur secondary to bubonic and pneumonic plague. It is the third most common form of plague.

Recent Outbreaks

Plague is endemic in many African nations, Russia, the Americas, and Asia. In 2003, nine countries reported 2118 plague cases to the World Health Organization, including 182 fatalities. The only outbreak in 2003 was in a village in Algeria, where 11 people were infected and one person died. This was the first outbreak in 50 years. Madagascar and the Democratic Republic of the Congo are the two countries with the highest incidences of Plague, with an average of 600-800 cases per year.

The most recent outbreak of the plague occurred in Zobia, Democratic Republic of the Congo. The outbreak began among diamond mine workers. By the time the outbreak ended in March 2005, 130 had been infected, and 57 had died.