Overview of Anthrax
Anthrax is a disease most commonly found in plant eating animals such as sheep and cattle and to a lesser extent goats, horses and hogs. The disease is found throughout the world and outbreaks among animal populations do occur. However, transmission to humans in the United States is extremely rare. The causative agent is Bacillus anthracis which may be found in two forms. The first is a living growing bacterial form which requires the proper conditions (ex. nutrients) to multiply. This form produces disease in a suitable host. The second form is a spore which is produced by the bacterial form as a survival mechanism during adverse conditions. The spores can survive for many years in soil and are capable of infecting a host under the proper circumstances. Anthrax spores can be found in soils in many parts of the U.S. and outbreaks of the disease do occur randomly (ex. an outbreak among cattle occurred Reno, NV in the summer of 2000).
The initial exposure to Anthrax occurs from contact with a sufficient number of spores which can then begin to grow in the host. In humans, the disease is usually found in two types of high risk groups, agricultural workers directly exposed to diseased animals and industrial workers handling animal products contaminated with spores (e.g. woolsorters disease from wool). Human to human transfer of the disease in not known to happen and no precautions are recommended when visiting or handling infected persons. Obviously, exposure to large numbers of spores by inhalation can be a means of contracting the disease. The minimal inhaled effective dose in humans is estimated to be between 8,000 and 12,000 spores depending on the size of the particles. Studies done in industrial settings have shown that individuals exposed to up to several hundred particles per hour are rarely affected.
There are three primary forms of the disease in humans. The first is the cutaneous form in which spores enter the skin through a cut or abrasion. Initially, the point of infection appears as a raised itchy bump but after 1-2 days develops into a painless ulcer with a characteristic black center. Without treatment about 20% of the cutaneous cases will be fatal. The second form is intestinal which occurs due the consumption of contaminated meat. The symptoms are due to severe inflammation of the intestinal tract and include nausea, loss of appetite, fever followed by abdominal pain, vomiting of blood and severe diarrhea. Approximately 25% to 60% of untreated cases result in death. The inhalation form is the third and most serious type of the disease and results from inhaling a sufficient number of Anthrax spores. The disease initially manifests as flu-like symptoms which may last from one to several days depending on the initial exposure. Following a period of no noticeable effects, a second round of symptoms occur including fever, fatigue, severe difficulty in breathing and chest pain. This form of the disease is almost always fatal if untreated.
The current field test is not definitive and can result in false positives because it reacts with other bacteria, and false negatives because low levels of Anthrax spores may not cause a positive result with the test. According to representatives of the Nevada State Health Department and the Clark County Health District, the rapid field test is not recommended for use at present. Other techniques are available for the detection of Anthrax, essentially all of which must be performed in a clinical laboratory environment and the definitive diagnosis can take several days. Common methods of testing include culture of the organism from nasal swabs (spores) and body fluids, detection of immune antibodies specific to the Anthrax bacterium and detection of Anthrax specific DNA from infected persons or contaminated items.
There are two available types of treatment and prevention available for Anthrax. The first is the use of antibiotics which have proven highly effective when administered early. The Food and Drug Administration (FDA) has approved three antibiotics for the treatment of anthrax - Penicillin, Doxycycline and Ciprofloxacin - although a number of other antibiotics have been used successfully for treatment. Treatment with one of these drugs has proven effective when administered within the first 24 to 48 hours following exposure. In special circumstances antibiotics can be use in a preventative measure to individuals at high risk of exposure, although, this is not recommend for as a widespread practice. The second type of preventative measure is the use of a vaccine which has been available since 1970. The vaccine course consists of six injections administered over time. The main drawbacks of the vaccine are that immunity does not occur until about twelve months after the initial dose and the vaccine is only available to high risk individuals.
ANTHRAX AS A BIOLOGICAL WEAPON
Anthrax has been a potential biological agent since at least the 1950s and at present a number of countries throughout the world are thought to have stockpiled large quantities of Bacillus anthracis spores. As an example, an explosion at a former Soviet Union bio-weapons laboratory caused over fifty deaths resulting from the release of about 20 pounds of purified spores. Breathing in a sufficiently large number of spores can result in the inhalation form of the disease. The spores are very small and can be dispersed in the form of an aerosol which can be found downwind for a reported 12 miles. Likewise, dispersal of the purified spores in building air handling systems can potentially spread the disease. Delivery systems can include missiles, artillery, bombs and sprayers (e.g. crop duster airplanes). However, it should be noted that the production, purification and dissemination of sufficiently large quantities of Anthrax spores resulting in the potential infection of a large population requires relatively sophisticated knowledge and equipment. Also, it should be remembered that rapid detection and treatment are the keys to preventing spread of Anthrax as evidenced by the low number of diagnosed cases of the disease since the first Florida instance was seen.
RESPONSE BY LAW ENFORCEMENT AND HEALTH PERSONNEL
A program detailing the responsibilities of the various law enforcement, fire department and health personnel is currently in place. In general, calls from persons concerned that they have been exposed will be handled first by dispatchers at the non-emergency Clark County number (311) using a screening process consisting of a series of questions which will determine whether the caller will be connected to trained individuals from the Clark County Health District who will perform an indepth interview. Depending on the results from this process, LVMPD or fire department personnel may be dispatched. Once the potential exposure is evaluated by police or fire personnel, a judgement will be made as to whether trained investigators from the Clark County Health District will respond. At this point decisions will be made following a detailed examination of the circumstances of the potential Anthrax exposure with respect to collection of materials, treatment of individuals and other relevant matters. When necessary, as in the case of a spill, protective equipment consisting of Tyvex suits, latex gloves and respirators with HEPA filters should be worn at a minimum. Handling and packaging of potentially contaminated material is detailed in a news release by the Clark County Health District and a CDC Health Advisory. More detailed information can be obtained from the Clark County Health District, the Nevada State Health Laboratory and the Centers for Disease Control (CDC) web page.
*** It should be noted that the above listed information is meant to be an overview only and can change as events progress, specific questions should be addressed to the appropriate agency or individual.