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Major Biological Agents

Anthrax is an acute infectious disease caused by a spore-forming bacteria called Bacillus anthracis. Anthrax is found world-wide and most commonly causes disease in hoofed mammals and can also infect humans. The last human case of anthrax in Arizona was reported in 1957. Symptoms of disease vary depending on how the disease was contracted, but usually occur within 7 days after exposure. The serious forms of human anthrax are inhalation anthrax, cutaneous anthrax, and intestinal anthrax.

Initial symptoms of inhalation anthrax infection may resemble a common cold. After several days, the symptoms may progress to severe breathing problems and shock. Inhalation anthrax is often fatal. The intestinal disease form of anthrax may follow the consumption of contaminated food and is characterized by an acute inflammation of the intestinal tract. Initial signs of nausea, loss of appetite, vomiting, and fever are followed by abdominal pain, vomiting of blood, and severe diarrhea. Direct person-to-person spread of anthrax is extremely unlikely, if it occurs at all. Therefore, there is no need to immunize or treat contacts of persons ill with anthrax, such as household contacts, friends, or coworkers, unless they also were also exposed to the same source of infection.

In persons exposed to anthrax, infection can be prevented with antibiotic treatment. Early antibiotic treatment of anthrax is essential–delay lessens chances for survival. Anthrax usually is susceptible to penicillin, doxycycline, and fluoroquinolones. An anthrax vaccine also can prevent infection. Vaccination against anthrax is not recommended for the general public to prevent disease and is not available.

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. The botulinum toxin is the most potent lethal substance known to man. C. botulinum is the name of a group of bacteria commonly found in soil. These rod-shaped organisms grow best in low oxygen conditions. The bacteria form spores which allow them to survive in a dormant state until exposed to conditions that can support their growth. There are seven types of botulism toxin designated by the letters A through G; only types A, B, E and F cause illness in humans, the others are know to cause illness in wildlife. There are three main kinds of botulism. Food-borne botulism is caused by eating foods that contain the botulism toxin. Wound botulism is caused by toxin produced from a wound infected with C. botulinum. Infant botulism is caused by consuming the spores of the botulinum bacteria, which then grow in the intestines and release toxin. All forms of botulism can be fatal and are considered medical emergencies. Food-borne botulism can be especially dangerous because many people can be poisoned by eating a contaminated food.

Brucellosis is caused by an infection with bacteria in the Brucella genus. It is an illness characterized by fever, night sweats, extreme tiredness, anorexia (loss of appetite), weight loss, headache, and arthralgia (pain in the joints). Six species of Brucella are currently presently known, of which Brucella melitensis, Brucella suis, and Brucella abortus have public health implications. B. melitensis occurs more frequently than the other types in the general population and it is the most pathogenic and invasive species, followed, in order, by B. suis and B. abortus.

Cholera is an acute, diarrheal illness caused by infection of the intestine with the bacterium Vibrio cholerae. Disease occurs through the action of the V. cholerae Enterotoxin. The illness is often mild or without symptoms, but sometimes it can be severe. Approximately one in 20 infected persons has severe disease characterized by profuse watery diarrhea, vomiting, and leg cramps. In these persons, rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours.

Ebola Virus
Viral hemorrhagic fevers are a group of diseases caused by viruses from four distinct families of viruses: filoviruses, arenaviruses, flaviviruses, and bunyaviruses. The usual hosts for most of these viruses are rodents or arthropods (such as ticks and mosquitoes). In some cases, such as Ebola virus, the natural host for the virus is unknown. All forms of viral hemorrhagic fever begin with fever and muscle aches. Depending on the particular virus, the disease can progress until the patient becomes very ill with respiratory problems, severe bleeding, kidney problems, and shock. The severity of viral hemorrhagic fever can range from a relatively mild illness to death.

Plague, the dreaded "Black Death" of the Middle ages, is a bacterial disease found primarily in rodents and is spread between rodents by infected fleas. The disease is caused by the gram-negative bacteria, Yersinia pestis. Humans can get plague from several transmission routes including: contact with infected rodents, bites from infected fleas, and inhaling aerosolized droplets from the coughing of other infected humans or animals.

Q Fever
Q Fever is a disease caused by Coxiella burnetii, a rickettsiae, which is a type of small bacteria that live inside cells. It is a disease of agriculture animals, in which the organisms grow to high concentrations in the placental tissues. The disease was first called "Query Fever" because it’s cause was unknown. The disease has been reported from all parts of the world and because of the mildness of many cases, more cases occur than are reported. Q fever is rare in Arizona, with five cases reported in the last twelve years.

Ricin is a protein toxin that is readily produced from castor beans (Ricinus communis), which are ubiquitous throughout the world. It acts as a cellular poison by inhibiting protein synthesis. Naturally-occurring cases of ricin involve ingestion of castor beans, and are marked by severe gastrointestinal symptoms, vascular collapse, and death.

Smallpox is a serious, contagious, and sometimes fatal infectious disease. There is no specific treatment for smallpox disease, and the only prevention is vaccination. The name smallpox is derived from the Latin word for "spotted" and refers to the raised bumps that appear on the face and body of an infected person.
Staphylococcal Enterotoxin B
Staphylococcal Enterotoxin B (SEB) is one of the several exotoxins produced by Staphylococcus aureus, causing food poisoning when ingested. Staphylococcal toxins can also cause illness if inhaled in low doses. The toxin interacts with the individual's immune system to produce a variety of effects.

Tularemia, a disease that affects both animals and man, is caused by the bacteria Francisella tularensis. Its name relates to the description in 1911 of a plague-like illness in ground squirrels in Tulare county, California (hence the name tularemia) and the subsequent work done by Dr. Edward Francis. Rabbits and rodents are most often involved in disease outbreaks. Some examples of animals, other than rabbits, that carry tularemia are meadow mice, ground hogs (woodchucks), ground squirrels, tree squirrels, beavers, coyotes, muskrats, opossums, sheep, and various game birds.

Viral Hemorrhagic Fevers
The term viral hemorrhagic fever (VHF) refers to a group of illnesses that are caused by several distinct families of viruses. While some types of hemorrhagic fever viruses can cause relatively mild illnesses, many of these viruses cause severe, life-threatening disease. VHFs are caused by a variety of viruses from four distinct families: arenaviruses (Lassa fever and South American hemorrhagic fever viruses), filoviruses (Ebola and Marburg viruses), bunyaviruses (Crimean-Congo hemorrhagic fever, Rift Valley fever, and hantaviruses), and flaviviruses (yellow fever, tick-bone encephalitis, Kyasanur Forest, and dengue and Omsk hemorrhagic fever viruses).


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