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
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.
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 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
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.
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).