Anthrax: More Deadly Than Reported
Col. Byron Weeks, M.D., Ret.
Monday, Oct. 15, 2001
Dr. Weeks has had a distinguished medical and military career with the U.S. Air Force Medical Corps. Dr. Weeks began military service as the youngest flight surgeon in the U.S. Air Force during the Korean War. After 15 years of military service, during which he served in senior posts, including Hospital Commander at Bitburg Air Force Base, Germany, Dr. Weeks retired and entered private practice. During the past two decades, he has focused his studies on the threat of biological and chemical agents as weapons of war. Dr. Weeks has lectured and written numerous articles on infectious diseases and biological warfare.
Anthrax poses a significant threat to Americans and should not be dismissed as an ineffective bio-weapon, as many media are portraying it. Bacillus anthracis, the causative agent of anthrax, is a Gram-positive, spore-forming rod.
The spores are the usual infective form. Anthrax is primarily a zoonotic (communicable from animals to humans) disease of herbivores, with cattle, sheep, goats and horses being the usual domesticated animal hosts, but other animals may be infected.
Humans generally contract the disease when handling contaminated hair, wool, hides, flesh, blood and excreta of infected animals and from manufactured products such as bone meal.
Infection is introduced through scratches, abrasions and wounds, or by inhaling spores, eating insufficiently cooked infected meat, or being bitten by flies.
The primary concern for intentional infection by this organism is through inhalation after aerosol dissemination of spores. All human populations are susceptible.
The spores are very stable and may remain viable for many years in soil and water. They resist sunlight for varying periods.
History and Significance
Anthrax spores were weaponized by the United States in the 1950s and 1960s, before the old U.S. offensive program was terminated.
Other countries have weaponized this agent or are suspected of doing so. Anthrax bacteria are easy to cultivate and spore production is readily induced.
Moreover, the spores are highly resistant to sunlight, heat and disinfectants - properties which could be advantageous when choosing a bacterial weapon.
Weaponized spores are heartier than ones that Western medical experts have seen before; therefore, the risk from these spores is greater than many may believe.
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, and in 1995 Iraq admitted to weaponizing anthrax.
Dr. Ken Alibek, a recent defector from the former Soviet Union's biological weapons program, revealed that the Soviets had produced anthrax in ton quantities for use as a weapon.
This agent could be produced in either a wet or dried form. Coverage of a large ground area could theoretically be facilitated by multiple spray bomblets containing desiccated spores disseminated from a missile warhead at a predetermined height above the ground.
Anthrax presents as three somewhat distinct clinical syndromes in humans: cutaneous, inhalational and gastrointestinal.
The cutaneous form (also referred to as a malignant pustule) occurs most frequently on the hands and forearms of persons working with infected livestock.
It begins as a papule (bump) followed by formation of a fluid-filled vesicle (blister). The vesicle typically dries and forms a coal-black scab (eschar); hence, the term anthrax (from the Greek for coal). This local infection can occasionally disseminate into a fatal systemic infection.
Gastrointestinal anthrax is rare in humans, and is contracted by the ingestion of insufficiently cooked meat from infected animals.
Endemic inhalational anthrax, known as woolsorter's disease, is also a rare infection, contracted by inhalation of the spores. It occurs mainly among workers in industrial settings who handle infected hides, wool and furs.
Inhalational anthrax usually has an incubation period of 1-6 days, although in an outbreak in Sverdlovsk in the Soviet Union, one patient had a six-week interval between exposure and onset. [See note at end for more on outbreak.]
Because the number of spores needed to kill an animal from inhalational anthrax is much smaller than for a human, animals will be the first to shows symptoms of the disease and die. Thus, the unusual incidence of deaths of dogs, cats and other pets may serve as an early warning of an anthrax outbreak.
In humans, the mortality of untreated cutaneous anthrax ranges up to 25 percent; in inhalational and intestinal cases, the case fatality rate is 90 percent to 100 percent.
After an incubation period of 1-6 days, presumably dependent upon the strain and number of organisms inhaled, the onset of inhalational 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 (from hours to 2-3 days), followed by the abrupt development of severe respiratory distress with sweating, shortness of breath, stridor (sound of respiration when airways are obstructed) and cyanosis (bluish color of skin due to insufficient oxygen in blood).
Septicemia (blood poisoning), shock and death usually follow within 24-36 hours after the onset of respiratory distress.
Physical findings are typically non-specific, especially in the early phase of the disease.
The chest X-ray often reveals a widened mediastinum (chest cavity) with or without pleural effusions late in the disease in about 55 percent of the cases, but typically is without lung infiltrates.
Pneumonia generally does not occur; therefore, organisms are not typically seen in the sputum. 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.
Approximately 50 percent of cases are accompanied by hemorrhagic meningitis, and therefore organisms may also be identified in cerebrospinal fluid.
Only vegetative encapsulated bacilli are present during infection; spores are not found within the body unless it is opened to ambient air.
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 (white blood cell) count becomes elevated and remains so until death.
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 to penicillin in vitro (in the laboratory). However, Russia has developed new strains that are resistant to penicillin, tetracyclines, erythromycin and probably other antibiotics, through laboratory manipulation of organisms.
All naturally occurring strains tested to date have been sensitive to erythromycin, chloramphenicol, gentamicin, and ciprofloxacin (cipro).
In the absence of antibiotic sensitivity data, empiric intravenous antibiotic treatment should be instituted with cipro at a dose of 400-800 mg IV twice daily at the earliest signs of disease.
U.S. military policy (FM 8-284) currently recommends ciprofloxacin (400 mg IV every 12 hours) or doxycycline (200 mg IV load, followed by 100 mg IV every 12 hours) as initial therapy, with penicillin (4 million units IV every 4 hours) as an alternative once sensitivity data is available.
Published recommendations from a public health consensus panel recommends ciprofloxacin as initial therapy.
Recommended treatment duration of the active case is 60 days, and should be changed to oral therapy as clinical condition improves.
Supportive therapy for shock, fluid volume deficit and inadequacy of airway may all be needed.
Standard precautions are recommended for patient care.
There is no evidence of direct person-to-person spread of disease from inhalational anthrax.
After an invasive procedure or autopsy, the instruments and area used should be thoroughly disinfected with a sporicidal (spore-killing) agent such as formaldehyde. Sodium or calcium hypochlorite can be used, but with the caution that the activity of hypochlorites is greatly reduced in the presence of organic material.
Vaccine: A licensed vaccine (Anthrax Vaccine Adsorbed) made solely by BioPort Corp. is derived from sterile culture fluid supernatant taken from an attenuated strain.
Therefore, the vaccine does not contain live or dead organisms. However, because of numerous severe immunologic reactions to this vaccine, I cannot recommend it.
Antibiotics: Both military doctrine and a public health consensus panel recommend prophylaxis with ciprofloxacin (500 mg orally twice a day) as the first-line medication in a situation with anthrax as the presumptive agent.
Ciprofloxacin recently became the first medication approved by the FDA for prophylaxis after exposure to a biological weapon (anthrax).
Bioweaponized anthrax is very likely to be resistant to alternatives such as doxycycline (100 mg orally twice a day) or amoxicillin (500mg orally every 8 hours).
Should an attack be confirmed as anthrax, antibiotics should be continued for at least 4 weeks in all those exposed.
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.
"Biohazard" by Ken Alibek, M.D., Ph.D.
USAMRIID: Manual of Biological Warfare
In April 1979, an anthrax outbreak in the Soviet city of Sverdlovsk, roughly 850 miles east of Moscow, killed 66 of 94 infected people. The first victim died after 4 days; the last one died 6 weeks later.
The Soviet government claimed the deaths were caused by intestinal anthrax from tainted meat. It was not until 1992 that President Boris Yeltsin admitted the outbreak was the result of military activity at a suspected Soviet biological weapons facility located in the city.