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CDC's Dirty Dozen: 12 Diseases Watched as Terrorist Threats

Ebola made the cut, as did anthrax and botulism. Find what other diseases government officials are closely monitoring.

The Centers for Disease Control and Prevention has compiled a "Dirty Dozen" list, naming 12 diseases that they and other officials are monitoring because the infectious agents pose significant bio-terrorism threats, according to the CDC and a forthcoming paper in the journal Building and Environment.

Efforts are underway to design biosensors to detect the Dirty Dozen, which are diseases that have high mortality rates, can be difficult to diagnose, generate public panic and more, explain lead author Elvira Brauner and colleagues from Aalborg University.

First on the list is anthrax.

"The use of biological agents against enemies has persisted throughout centuries and the use of anthrax spores on civilians in (the) USA in 2001 suggests a growing worldwide threat," explained Brauner and her team. "Safeguarding spaces under attack requires rapid detection and identification."

Anthrax, spread by spores of the bacteria Bacillus anthracis, can cause skin lesions, pneumonia and gastrointestinal problems.

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Bubonic plague, which affects the lungs, is highly contagious, and can lead to mass outbreaks across populations. History shows that population levels have suffered worldwide due to this and other forms of plague, with around 75 million people globally perishing during the 14th century Black Death.

A study in the journal Infection, Genetics and Evolution determined that risk factors for Bubonic plague and other forms of plague still exist today.

Author Christian Devaux, an internist in Salem, Oregon, explained that multi-drug resistant pathogens are currently emerging and spreading rapidly, particularly in developing countries. More frequent travel now has the potential to spread plague all the more. He hopes that we will learn from history, working quickly to contain any outbreaks.

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Tularemia, or rabbit fever, can be fatal when introduced into the lungs. As a result, it has been developed as a bioweapon by several countries around the world, according to microbiologist Karl Klose, a professor at the University of Texas at San Antonio.

"Natural cases of tularemia are very rare," Klose said. "However, the use of Francisella tularensis as a bioweapon could be devastating because it takes very little of the bacterium to cause an infection."

He and other researchers are working to develop a vaccine to protect against tularemia infection.

Brucellosis bacteria cause a chronic disease causing fever and joint pain in humans. Animal hosts carrying the bacteria may show signs of swelling, become infertile, and exhibit other symptoms.

"Brucellosis is a globally important disease that affects both human and animal populations," said Kathleen Alexander, an associate professor of wildlife in the College of Natural Resources and Environment at Virginia Tech, who has studied the bacteria in buffalo. "It spreads from animals to humans, and the buffalo bears further study in order to understand the ecology of the pathogen."

Some of the planet's most deadly diseases, such as HIV/AIDS, first emerged from consumption of, or other close exposure to, infected meat and animals. Usually "bush meat" is thought of as exotic and coming from meat not usually seen in grocery stores. Brucellosis is a reminder that more commonplace animals, such as buffalo, may harbor zoonotic diseases too.

As of now, melioidosis is primarily a tropical disease spread to humans and animals through contaminated soil and water. It is nicknamed the "Vietnam time bomb" because of the delayed reaction of the bacteria and because it is one of the top three causes of death by infectious disease in Vietnam and other parts of South East Asia.

Like Ebola, it can enter a person's body through small skin lesions. Scientists are continuing to work on methods to defuse this bacterial "bomb."

Q fever is one of the world's most infectious diseases, according to Didier Raoult of the Universite de la Mediterranee. Raoult explained that inhalation of a single bacterium is sufficient to infect a person. It can cause a severe infection of the inner lining of the heart or heart valves.

A large scale Q fever outbreak occurred some years ago in the Netherlands, infecting thousands and resulting in several deaths. Illness typically results from contact with infected animals, such as cattle, goats and sheep. The potent bacteria is also being eyed by terrorists, however, hence its Dirty Dozen listing.

Although naturally occurring smallpox was eradicated in 1977, there is concern that bioterrorists might obtain smallpox from a laboratory and release it into the population.

A vaccine is available, but the supply may be insufficient for sudden, mass administration. Prior studies have recommended that, in the event of a bioterrorist attack, the vaccine should first be used on individuals who have previously not been vaccinated, since the vaccine can be effective for decades.

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Outbreaks of naturally-occurring VEE periodically ravage Central and South America, infecting tens of thousands of people and other mammals, such as horses, donkeys and mules. Mosquitoes can harbor the deadly virus and spread it via their bites.

During the Cold War, both the United States and the Soviet Union developed the virus into a biological weapon, according to researchers at the University of Texas Medical Branch at Galveston, who have studied the protein structure of VEE. They and others are concerned that the virus in future could pose bioterrorism threats.

The 2014 Ebola epidemic is the largest in history, according to the CDC. It has killed thousands of people in West Africa, and the death toll continues to grow.

While Ebola remains in the headlines, it is just one of several viruses with similar symptoms and potential outcomes. Marburg virus, for example, can also cause hemorrhagic fever, meaning dysfunction in the body's network of blood vessels that can cause bleeding. Marburg is also spread when a person comes into contact with the bodily fluids of an infected person.

Ebola, Marburg and related other viral diseases are considered to be high-priority bio-agents. Brauner and her team explain that these bio-agents "can be defined as being easily disseminated or transmitted from person to person with high morbidity and mortality rates, difficult diagnosis, creation of public panic and social disruption as well as major public health impact potential. Compared to conventional weapons, relatively small amounts of biological agents may cause high numbers of casualties."

Experts, however, continue to debate how viable the Ebola virus and related ones could be as bioweapons. Some bioterrorism experts, like biological anthropologist Peter Walsh of Cambridge University, believe that the Ebola virus could pose a significant bioterrorist threat. Others, such as New York physician Robert Leggiadro and SecureBio's Hamish de Bretton-Gordon, think that Ebola will not be used as a bioterrorism agent any time soon because they say it is difficult to work with and "weaponize."

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Botulism is a rare and often fatal paralytic illness due to a neurotoxin produced by Clostridium botulinum bacteria, which can appear in rotted, uncooked foods and in soil. It is listed as a Tier 1 agent by the Centers for Disease Control & Prevention because the botulinum toxin is also a potential biological weapon. Researchers continue to study how the toxin enters the bloodstream in hopes of blocking its absorption.

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When purified, the toxin ricin, derived from a naturally occurring protein in the seeds of the castor oil plant, can kill an adult human with an amount comparable to just a few grains of table salt. Many countries in the past, including the U.S., investigated ricin for its military potential. Because ricin is so easy to obtain and so toxic, public health experts regard it as one of the top bioterror agents.

The good news, announced a few years ago at the 241st National Meeting and Exposition of the American Chemical Society, is that ordinary household bleach appears to be an effective, low-cost and widely available way to decontaminate surfaces that might be tainted with ricin. Castor oil remains a key raw material in the manufacture of everything from soaps to paint, so thorough cleaning of surfaces at such manufacturing plants is important.

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Around 20 percent of all humans are persistently colonized with Staphylococcus aureus bacteria, a leading cause of skin infections and one of the major sources of hospital-acquired infections, including at least one strain that is antibiotic-resistant. This bad bug produces the deadly toxin SEB.

As for other deadly agents on this list, the U.S. and additional countries in the past have studied SEB as a biological agent. There is now concern that terrorists could deploy it as a bioweapon.

To the rescue is a project called "Bio-protect." It and others, according to Brauner and her team, seek to develop "a fast alert, mobile, easy-to-use device to be applied in detection and identification in airborne pathogenic bacteria, spores, viruses and toxins." Efforts are also underway to develop better treatments for SEB and other Dirty Dozen health threats.

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