Cybermed Update September 2001

ANTHRAX (malignant edema, woolsorters' disease)


The heart has its reasons which reason knows nothing of.

Blaise Pascal (1623 - 1662)


 

Anthrax is an infectious bacterial disease spread by contact with infected animals, handling infected products, eating infected meat, or breathing weapon-dispersed anthrax spores.

There has been heightened concern with the recent "Attack on America" of the use of biological agents by terrorist. There are many different types of biological agents but the most commonly heard/mentioned is Anthrax. I have sourced information from various sites to give an overview of what this disease is all about.

What it is:

Anthrax (Pronounced As: anthraks) is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax most commonly occurs in wild and domestic lower vertebrates (cattle, sheep, goats, camels, antelopes, and other herbivores), but it can also occur in humans when they are exposed to infected animals or tissue from infected animals.

Anthrax is most common in agricultural regions where it occurs in animals. These include South and Central America, Southern and Eastern Europe, Asia, Africa, the Caribbean, and the Middle East. When anthrax affects humans, it is usually due to an occupational exposure to infected animals or their products. Workers who are exposed to dead animals and animal products from other countries where anthrax is more common may become infected with B. anthracis (industrial anthrax). Anthrax in wild livestock has occurred in the United States.

Anthrax infection can occur in three forms: cutaneous (skin), inhalation, and gastrointestinal. B. anthracis spores can live in the soil for many years, and humans can become infected with anthrax by handling products from infected animals or by inhaling anthrax spores from contaminated animal products. Anthrax can also be spread by eating undercooked meat from infected animals. It is rare to find infected animals in the United States.A tough protective coat allows the bacteria to survive for decades as spores.

Anthrax spores were weaponized by the United States in the 1950's and 1960's before the old U.S. offensive program was terminated. Other countries have weaponized this agent or are suspected of doing so. The anthrax bacterium is easy to cultivate and spore production is readily induced. Spores are highly resistant to sunlight, heat and disinfectants - properties which could be advantageous when choosing a bacterial weapon. Iraq admitted to a United Nations inspection team in August of 1991 that it had performed research on the offensive use of B. anthracis prior to the Persian Gulf War of 1991, and in 1995 Iraq admitted to weaponizing anthrax. This agent could be produced in either a wet or dried form, stabilized for weaponization by an adversary and delivered as an aerosol cloud either from a line source such as an aircraft flying upwind of friendly positions, or as a point source from a spray device. Coverage of a large ground area could also be theoretically facilitated by multiple spray bomblets disseminated from a missile warhead at a predetermined height above the ground.

Incubation period - 1 to 6 days between exposure and symptoms.

Cutaneous: Most (about 95%) anthrax infections occur when the bacterium enters a cut or abrasion on the skin, such as when handling contaminated wool, hides, leather or hair products (especially goat hair) of infected animals. Skin infection begins as a raised itchy bump that resembles an insect bite but within 1-2 days develops into a vesicle and then a painless ulcer, usually 1-3 cm in diameter, with a characteristic black necrotic (dying) area in the center. Lymph glands in the adjacent area may swell. About 20% of untreated cases of cutaneous anthrax will result in death. Deaths are rare with appropriate antimicrobial therapy.

Inhalation: Initial symptoms may resemble a common cold. After several days, the symptoms may progress to severe breathing problems and shock. Inhalation anthrax is usually fatal.

Intestinal: The intestinal disease form of anthrax may follow the consumption of contaminated meat and is characterized by an acute inflammation of the intestinal tract. Initial signs of nausea, loss of appetite, vomiting, fever are followed by abdominal pain, vomiting of blood, and severe diarrhea. Intestinal anthrax results in death in 25% to 60% of cases.

Diagnosed by:

After an incubation period of 1-6 days, presumably dependent upon the dose and strain of inhaled organisms, the onset of inhalation anthrax is gradual and nonspecific. Fever, malaise, and fatigue may be present, sometimes in association with a nonproductive cough and mild chest discomfort. These initial symptoms are often followed by a short period of improvement (hours to 2-3 days), followed by the abrupt development of severe respiratory distress with dyspnea, diaphoresis, stridor, and cyanosis. Shock and death usually follow within 24-36 hours after the onset of respiratory distress. Physical findings are typically non-specific. The chest X-ray may reveal a widened mediastinum pleural effusions late in the disease in about 55% of the cases, but typically is without infiltrates. Bacillus anthracis will be detectable by Gram stain of the blood and by blood culture with routine media, but often not until late in the course of the illness. Only vegetative encapsulated bacilli are present during infection. Spores are not found within the body unless it is open to ambient air. Studies of inhalation anthrax in non-human primates (rhesus monkey) showed that bacilli and toxin appear in the blood late on day 2 or early on day 3 post-exposure. Toxin production parallels the appearance of bacilli in the blood and tests are available to rapidly detect the toxin. Concurrently with the appearance of anthrax, the WBC count becomes elevated and remains so until death.

Treatment:

Almost all inhalational anthrax cases in which treatment was begun after patients were significantly symptomatic have been fatal, regardless of treatment. Penicillin has been regarded as the treatment of choice, with 2 million units given intravenously every 2 hours. Tetracyclines and erythromycin have been recommended in penicillin allergic patients. The vast majority of naturally-occurring anthrax strains are sensitive in vitro to penicillin. However, penicillin-resistant strains exist naturally, and one has been recovered from a fatal human case. Moreover, it might not be difficult for an adversary to induce resistance to penicillin, tetracyclines, erythromycin, and many other antibiotics through laboratory manipulation of organisms. All naturally occurring strains tested to date have been sensitive to erythromycin, chloramphenicol, gentamicin, and ciprofloxacin. In the absence of information concerning antibiotic sensitivity, treatment should be instituted at the earliest signs of disease with intravenous ciprofloxacin (400 mg q 8-12 hrs) or intravenous doxycycline (200 mg initially, followed by 100 mg q 12 hrs). Supportive therapy for shock, fluid volume deficit, and adequacy of airway may all be needed.

Standard Precautions should be practiced. After an invasive procedure or autopsy, the instruments and area used should be thoroughly disinfected with a sporicidal agent. Iodine can be used, but must be used at disinfectant strengths, as antiseptic-strength iodophors are not usually sporicidal. Chlorine, in the form of sodium or calcium hypochlorite, can also be used, but with the caution that the activity of hypochlorites is greatly reduced in the presence of organic material.

Treatment is usually not effective after symptoms are present.

High dose antibiotic treatment after symptoms appear can lower the death rate from 99% to about 80%.

PROPHYLAXIS

Vaccine: A licensed vaccine is derived from sterile culture fluid supernatant taken from an attenuated strain. The vaccination series consists of six 0.5 ml doses SC at 0, 2, and 4 weeks, then 6, 12 and 18 months, followed by yearly boosters. Limited human data suggest that the vaccine protects against cutaneous anthrax. There is insufficient data to know its efficacy against inhalational anthrax in humans, although studies in rhesus monkeys indicate that good protection can be afforded after only two doses (15 days apart) for up to 2 years. However, it should be emphasized that the vaccine series should be completed according to the routine 6 dose primary series. As with all vaccines, the degree of protection depends upon the magnitude of the challenge dose; vaccine-induced protection could presumably be overwhelmed by extremely high spore challenge.

Contraindications for use of this vaccine include hypersensitivity reaction to a previous dose of vaccine and age < 18 or > 65. Reasons for temporary deferment of the vaccine include pregnancy; active infection with fever; or a course of immune suppressing drugs such as steroids. Reactogenicity is mild to moderate. Up to 6 percent of recipients will experience mild discomfort at the inoculation site for up to 72 hours (e.g., tenderness, erythema, edema, pruritus), while less than 1 percent will experience more severe local reactions, potentially limiting use of the arm for 1-2 days. Modest systemic reactions (e.g., myalgia, malaise, low-grade fever) are uncommon, and severe systemic reactions such as anaphylaxis, which precludes additional vaccination, are rare. The vaccine should be stored between 2-6 oC (refrigerator temperature, not frozen).

Antibiotics: The choice of antibiotics for prophylaxis is difficult to make; for example, it seems relatively easy to induce penicillin and tetracycline resistance in the laboratory. Therefore, prophylaxis with ciprofloxacin (500 mg po bid) or doxycycline (100 mg po bid) is recommended. If personnel are unvaccinated, a single 0.5 ml dose of vaccine should also be given subcutaneously. Should the attack be confirmed as anthrax, antibiotics should be continued for at least 4 weeks in all those exposed, and until all those exposed have received three doses of the vaccine. Two additional 0.5 ml doses of vaccine should be given 2 weeks apart in the unvaccinated; those previously vaccinated with fewer than three doses should receive a single 0.5 ml booster, while vaccination probably is not necessary for those who have received the initial three-doses of the primary series, within the previous six months. Upon discontinuation of antibiotics, patients should be closely observed; if clinical signs of anthrax occur, patients should be treated as indicated above. If vaccine is not available, antibiotics should be continued beyond 4 weeks and withdrawn under medical observation. Optimally, patients should have medical care available upon discontinuation of antibiotics, from a fixed medical care facility with intensive care capabilities and infectious disease consultants.

What these bacteria do:

In countries where anthrax is common and vaccination levels of animal herds are low, humans should avoid contact with livestock and animal products and avoid eating meat that has not been properly slaughtered and cooked. Also, an anthrax vaccine has been licensed for use in humans. The vaccine is reported to be 93% effective in protecting against anthrax. The anthrax vaccine is manufactured and distributed by BioPort, Corporation, Lansing, Michigan. The vaccine is a cell-free filtrate vaccine, which means it contains no dead or live bacteria in the preparation. The final product contains no more than 2.4 mg of aluminum hydroxide as adjuvant. Anthrax vaccines intended for animals should not be used in humans.

The Advisory Committee on Immunization Practices has recommend anthrax vaccination for the following groups:

Why is it a threat? Anthrax spores are the top choice in biological weapons for "germ warfare."

Anthrax is effective as a biological weapon because:

We KNOW there are potential adversaries developing it as a weapon.

There is no indication of exposure.

There is no effective treatment for unvaccinated victims of inhalational anthrax.

Recently there was a case of anthrax in Florida, USA. This public health message was released by CDC.(see below)

PUBLIC HEALTH MESSAGE REGARDING ANTHRAX CASE

The Florida State Department of Health and the CDC are investigating a case of anthrax in a 63-year-old male Florida resident. The diagnosis is confirmed by CDC's laboratory. So far this appears to be an isolated case. Anthrax is not contagious. The illness is not transmitted person to person. Sporadic cases of anthrax do occur in the United States, so a single case is not an indication of an outbreak. The last case of anthrax reported in the United States was earlier this year in Texas. The rapid identification of this single case is the result of the heightened level of disease monitoring being done by the public health and medical community. This is the disease monitoring system in action. Right now, there is no suggestion of other possible cases, but we are aggressively checking to see if other people are similarly ill. The Florida State Health Department and a team from CDC are aggressively investigating the source of infection. They are reconstructing the patient's schedule for the last few weeks to attempt to determine the location where the patient may have been exposed. A team of CDC epidemiologists were sent to Florida to look for any indications of exposure to this disease. Medical teams and supplies are prepared to be moved quickly if needed. CDC and state health officials are alerting health care providers to look for unusual cases of respiratory disease. Although anthrax starts out with flu-like symptoms, it rapidly progresses to severe illnesses, including pneumonia and meningitis. If anyone has been exposed, antibiotics are the appropriate preventive treatment. CDC has an emergency supply of antibiotics readily available for distribution. If the investigation of the cause of this illness indicated that you need antibiotics, your state and local health department will notify you and your physician and will assure you receive the drugs. Based on what we know right now, there is no need for people to take any extraordinary actions or steps. They should not go to a doctor or hospital unless they are sick. They should not buy and horde medicines or antibiotics. They should not buy gas masks. The public needs to understand that our public health system is on a heightened sense of alert for any diseases that may come from a biological attack. So we may have more reports of what may appear to be isolated cases. We're going to respond more aggressively to these cases than in the past.

Malaysia has been anthrax (animal) free for a long time.

CDC USA has a public health emergency preparedness and response site for the public health infrastructure to be prepared to prevent illness and injury that would result from biological and chemical terrorism, especially a covert terrorist attack. As with emerging infectious diseases, early detection and control of biological and chemical attacks depend on a strong and flexible public health system at the local, state and federal levels. In addition, primary health-care providers throughout the United States ( Malaysia) must be vigilant because they will probably be the first to observe and report unusual illnesses or injuries. The list of agents and information on them can be viewed at http://www.bt.cdc.gov/Agent/Agentlist.asp . Interestingly, Nipah virus ( http://www.vadscorner.com/paramyxo.html )is on this list!

For more information on Anthrax and other agents "click" on to http://www.vadscorner.com/anthrax.html .

Source:


The links to URL mentioned above are valid at the time of writing (6 October 2001).

Updated 15 January 2006.

This page can be accessed at http://www.vadscorner.com/internet55.html or at http://www.vadscorner.com/mma_internet.html.

Vads Corner Homepage ( http://www.vadscorner.com )