Anthrax: What, Who, How & Symptoms Information

An illness that has been recognized since before the middle ages. A naturally occurring bacterial disease of plant eating animals (elephants, goats, sheep, cattle, etc.), caused by the bacterium Bacillus anthracis that can infect all warm blooded animals including man.

Who gets anthrax?
Anthrax is primarily an occupational disease and was common in areas of farming and essentially, where all livestock are raised. Intensive livestock immunization programs have greatly reduced the occurrence of the disease among both animals and humans in much of the world, and most outbreaks occur in areas where immunization programs have become compromised or have not been implemented (primarily Africa and Asia; however, outbreaks occurred during the former Soviet Union and in Haiti the1990's ). It is occasionally identified in individuals who are exposed to dead animals and animal products such as wool and hair.

How is anthrax spread?
Anthrax spores can remain viable for several decades under suitable environmental conditions; thus, absence of cases does not equate to absence of risk. Humans can contract anthrax in three ways:

(1). Through cuts or breaks in the skin resulting from contact with an infected animal (cutaneous anthrax), resulting in local and possibly systemic (bloodstream) infection.

(2). From breathing anthrax spores resulting in an infection of the lungs (inhalational anthrax).

(3). From eating infected meat, resulting in gastrointestinal infection (gastrointestinal anthrax). Gastrointestinal anthrax is generally not considered a threat to U.S. forces. Man may become infected with anthrax by inhaling contaminated soil particles or by handling wool or hair from diseased animals. Infection of the intestinal tract can occur by eating undercooked meat from diseased animals.

The symptoms vary depending upon the type of exposure. For contact or cutaneous anthrax, itching will occur at the site of exposure followed by the formation of a lesion. Untreated contact anthrax has a fatality rate of 5-20 percent, but with effective antibiotic treatment, few deaths occur. Initial symptoms for inhalational anthrax are generally non-specific:
low grade fever, a dry hacking cough, muscle ache, and weakness.

The person may briefly improve after 2 to 4 days; however within 24 hours after this brief improvement, respiratory distress occurs with shock and death following shortly thereafter. Almost all cases of inhalational anthrax, in which treatment was begun after patients have exhibited symptoms, have resulted in death, regardless of post-exposure treatment.With skin exposure, a boil-like lesion appears which eventually forms a black center. A swelling of the lymph gland under the arm may occur. With respiratory exposure, symptoms may resemble the common cold and may progress to severe breathing problems and even death.

How soon after infection do symptoms appear?
The incubation period will usually begin after a 1 and up to a 40 day incubation period following exposure.

When and for how long is a person able to spread anthrax?
There are no reports of the disease spreading from human to human.

Does past infection with anthrax make a person immune?
A second attack with this disease is unlikely.

What is the medical countermeasure treatment for anthrax?
Prior to exposure, prevention through vaccination, using the FDA-licensed vaccine. Otherwise, antibiotics such as penicillin, ciprofloxacin, and doxycycline are the drugs of choice but tetracycline may also be prescribed for treatment of anthrax. Treatment with antibiotics must begin prior to the onset of symptoms and must include vaccination prior to discontinuing their use.

What can be the effect of not being treated for anthrax?
The disease could be fatal in untreated cases. Regardless of treatment after symptoms appear, inhalational anthrax is almost always fatal.

What can be done to prevent the spread of anthrax?
Anthrax vaccine is available for people in high-risk occupations. To prevent anthrax, carefully handle dead animals suspected of having anthrax; provide good ventilation when processing hides, fur, hair or wool; and vaccinate animals.

Dissemination and Infection
It is expected that anthrax spores will be disseminated or disseminated as an aerosol with crude sprayers causing inhalation anthrax. Because atmospheric stability is important to efficient spread, and because sunlight is highly toxic to biological agents, they are most likely to be delivered at night. Particles from 1 to 5 microns in size are most efficient in causing infection, and can be present in significant quantities more than 25 km downwind. The inhaled infectious dose in man is quite high, estimated @ 2500 particles. Nonimmunized workers in animal-hair mills have been shown to inhale 100/1000 infected particles/hour @ 5 microns, but are rarely affected. The addition of detergents, irritants, or immunosupressives to the aerosol may decrease the infective dose needed by up to 10-fold. It's likely that heavy smokers could be more susceptible, and to larger particle size however, there is no data available on this thought.

Clinical diagnosis
Inhalation anthrax (also known as "Woolsorter's" disease) is a biphasic illness. The first phase occurs when the spores are carried to the mediastinal lymph nodes by pulmonary macrophages and cause a suppurative infection with edema and hemorrhage. This phase is characterized by nonspecific flu-like symptoms; mild fever, malaise, fatigue, myalgia, nonproductive cough, and at times a sensation of chest oppression or pressure. Rhonchi may be heard with a stethoscope. The presence of such symptoms in a large number of personnel at once should raise the suspicion of anthrax. This phase can last for several days, or for as little as 24 hours in heavy infections, and can be followed by an asymptomatic period. A helpful radiographic sign is symmetrical enlargement of the superior mediastinum due to lymph node enlargement. The disease is treatable in this stage, but blood cultures will probably be negative (no data on this). Sputum cultures might have a higher yield, particularly if anthrax is specifically looked for.

The second phase develops suddenly with the development of severe shortness of breath and cyanosis. Hypotension and shock occur. The temperature may be elevated or subnormal due to shock, and perspiration is often profuse. Stridor may be present due to enlargement of the lymph nodes near the trachea. Chest exam shows moist, crepitant rales and signs of pleural effusion. Blood cultures are positive, and the bacteremia may be high enough for organisms to be visible on a Gram stained smear. The second, acute phase typically lasts less than 24 hours and usually ends in death despite therapy, due to the high number of toxin-producing organisms present by this stage in the illness.

Recommendations for therapy
The standard therapy for inhalation anthrax is intravenous penicillin G by continuous infusion, 50 mg/kg or 80,000 U/kg in the first hour, followed by 200 mg/kg or 320,000 U/kg over the following 24h. No data are available on the value on penicillin IM, but it would likely be less effective and larger doses might be required. Streptomycin, 1-2 g/24h IM has been described to be synergistic in combination with penicillin. An alternative regimen is erythromycin, 4g/24h by continuous infusion. In a biological warfare situation, however, vancomycin might be a part of any regimen that is recommended , in a dose of 500 mg every 6 hours. Intramuscular injection of vancomycin is painful. An inferior but possibly useful substitute for vancomycin would be oxacillin, methicillin, or nafcillin in appropriate dosages (use the PDR). Other drugs to which B. anthracis is generally considered susceptible include the first-generation cephalosporins, tetracycline, and chloramphenicol. Adjuvant therapy with hydrocortisone, 100-200 mg/day may be helpful in the case of malignant chest-wall and neck edema. As soon as in vitro susceptibility data are available, therapy should be adjusted to include effective drugs, and drugs to which the isolate is resistant should be eliminated.

If antibiotics are present in limited quantities, the least ill patients should be treated first, as patients in the second phase of the illness have a poor prognosis even with effective therapy. It is, however, appropriate to treat as many people as possible with whatever antibiotics if limited quantities are available.

Rationale for therapeutic recommendations
Most clinical isolates of anthrax are penicillin-susceptible. Virulent strains resistant to penicillin have been described at least since 1970, however. Because penicillin is cheap, it is likely that any strain used for biological warfare will be penicillin-resistant. Most penicillin-resistant organisms do so by producing beta-lactamases. The oxacillin group of semisynthetic penicillins are resistant to many beta-lactamases, thus the recommendation of these drugs as an alternative to vancomycin.

On the other hand, vancomycin resistance, except for a few strains of enterococcus, is primarily a rare laboratory phenomenon. In addition, vancomycin is an expensive compound and it would be prohibitive to produce industrial quantities of resistant organisms. Thus vancomycin should be considered the gold standard of empirical therapy in a biowar environment. Similarly, developing and producing a strain resistant to both erythromycin and penicillin would more than double the cost and difficulty of producing the bugs unless fairly sophisticated molecular techniques were employed. Since each piece of genetic baggage the organism has to carry will have unpredictable effects on virulence, and it's a very effective weapon already.

Anthrax as a biological warfare agent
Anthrax is the preferred biological warfare agent because: