Anthrax ======= þ LD50 - LD50 is 5000 spores; but even 1-10 spores in a monkey study still kills a lot of monkeys. Anthrax - The "prototypical" biologic agent. Bacillus anthracis is a natural zoonotic disease endemic worldwide - including the United States. The usual form of the disease is cutaneous anthrax - produced by transdermal inoculation with the organism. Ingestion is also possible producing oropharyngeal and gastrointestional forms of the disease. Usual endemic anthrax occurs through contact with infected animals or their body parts. The organism is a gram positive bacillus. The organism forms spores during adverse conditions that are relatively resistant to disinfection. The vegitative organism is killed with standard disinfectants. The concern here is inhalational anthrax - A disease so rare in the United States that most health care workers have never seen a case. Less than 18 cases have been reported in the US this century. Inhalation of a sufficient number of spores of respirable size (this is key) produces a hemmorhagic mediastinitis with pneumonia after an incubation period of 1-6 days. ARDS and multisystem organ failure may develop. Treatment at this point is high dose penicillin although quinolones probably have activity. Chloramphinicol and erythromycin can also be used. If the disease develops the case fatality is > 80%. The key point here is the form of the material. A culture of (non-spore) anthrax presents no significant risk - the organism is killed with bleach and other disinfectants. The spores are much more resistant to killing but can be killed with potassium permanganate and other strong (sporicide) oxidizers. To develop a significant risk of inhalational anthrax requires the generation of a respirable aerosol of 3 microns. This is not an easy task and there is no evidence this has occurred in this case. Phrophylaxis after exposure is possible with ciprofloxacin, doxycycline or penicillin being effective in models. IF (and this is a big IF - I have no data that this occurred) a human exposure can be prophylaxed with these drugs starting immediately after exposure and continuing until vaccination (see below) concludes. A vaccine (produced by the Michigan Dept of Public Health) exists (antigen generated from an attenuated strain and conjugated to aluminum hydroxide. The series is a 6 shot regimen at 0 2 4 weeks and 6 12 and 18 months. Protective antibodies develop in 91% after 2-3 doses. I do not believe this vaccine is available outside military sources as the entire supply (the exact amount is classified) is used by the miliatary for preexposure use for troops committed to the Middle East.. Let me know if you need additional information. Steve Tharratt ------------------------------------- The big problem with the vaccination is that it requires a series of six doses over a period of 18 months to accrue protection. Some data has suggested however that after the third dose (4 weeks) protection against the cutaneous route of anthrax can be afforded. There have also been studies in rhesus monkeys that show if you give them two doses 15 days apart there is some protection against inhaled anthrax for 2 years. Here is a scary quotes from The Commentary #60 (An Unclassified Canadian Security Intelligence Service Publication). "Some authors maintain that anthrax is an even more deadly agent. According to one study, in principle, if its spores were distributed appropriately, a single gram would be sufficient to kill more than one-third of the population of the United States. Of course, it is often pointed out that an attack of such magnitude would not be practically feasible. However, more realistic, smaller-scale scenarios still posit large numbers of casualties. For example, the U.S. Law Enforcement Assistance Administration in March 1977 warned that a single ounce of anthrax introduced into the air-conditioning system of a domed stadium could infect up to 80,000 spectators within an hour. And a 1972 study by the Advanced Concepts Research Corporation of Santa Barbara, California, postulated that an aerosol attack with anthrax spores on the New York City area could cause more than 600,000 deaths. Some indication of the scale of casualties to be expected from a deliberate attack can be gained from the fact that the accidental release of anthrax in Sverdlovsk, Russia, in 1979 is estimated to have killed between 400 and 1,200 people." > According to Harrison's Principles of Internal Medicine (and I'm > paraphrasing) the treatment for it is as follows: > > 1) High dose IV penicillin > 2) High dose IV steroids > 3) Kiss your ass goodbye ------------------------- Not to argue with Harrison's bible, I was also taught that for inhalational anthrax patients you use 2 million units of penicillin IV every two hours. It was suggested at that time if you have to opt for IV steroids, you might as well not bother and continue on to suggestion number 3 as listed above. There have been reports (at least one) of a person dying from a penicillin resistant strain of anthrax. There also have been documented cases of tetracycline resistance. All naturally occurring strains have been tested against and are sensitive to erythromycin, chloramphenicol, gentamicin and ciprofloxacin. It was also mentioned that it may not be all that hard to induce resistance in a laboratory to penicillin, erythromycin and tetracyclines by the enemy / terrorists. Thus, in the absence of knowing the antibiotic sensitivity one should initially opt for IV ciprofloxacin 400 mg q 8-12h as your first line or IV doxycycline IV 200 mg followed by 100 mg q12h as your second line until antibiotic sensitivity testing is completed. As an aside, almost every reported case of inhalational anthrax where the patient was symptomatic has been fatal regardless of what the medical profession did... so don't hold your breath .