Anthrax is a bacterial disease caused by the bacterium Bacillus anthracis (a large non-motile, aerobic, encapsulated, Gram-positive rod which has the capacity to make heat & dry-resistant spores (1 to 2 ?m in diameter) under adverse conditions. Oxygen is required for sporulation but not for germination of spores. Sporulation does not take place in living animals, so the disease is not transmissible from person to person, nor from animal to animal). In the environment, the bacteria exist as spores, which stay in topsoil and are ingested by the animals when grazing. Spores are very resistant to adverse conditions and can survive in the dry earth for years. By contrast spores are destroyed by:
-boiling for ten minutes, (ingestion of water infected by spores may transmit gastrointestinal form of anthrax)
-by potassium permanganate or hydrogen peroxide
-by diluted formaldehyde
Virulence is caused by three toxins, three proteins called anthratoxins, and an antiphagocytic capsular polypeptide. This is of some relevance for the production of vaccines
Incubation Period :
The period between exposure to infection and manifestation of symptoms, incubation, is usually within 2-7 days. However inhalation anthrax incubation may be up to six weeks (clinical observation) or even 8 weeks in the experimental infection in macacus.
Epidemiology and Transmission :
It is mainly a zoonotic disease (a disease of animals which can affect human beings) that occurs in domestic herbivores, goat, sheep, cow & wild animals. Human disease is most likely to occur in endemic regions by direct contact with infected carcasses or animal products. Anthrax occurs worldwide, endemic regions are Turkey, Iran, and part of Iraq. Industrial cases may occur anywhere & reflect exposure to wool (woolsorters disease) , imported animal carcass product such as bone meal (used for making glues) & hides.
Natural infection in humans is almost invariably acquired from exposure to infected animals or contaminated animal products. Infection occurs by the cutaneous route, this includes handling contaminated carcasses, wool, hides, bones, hair ,etc (95% of the cases); and only rarely(5% of the cases) by the inhalation route (usually seen only during generation of aerosols in an enclosed space associate with processing contaminated wool or hair ) or extremely rarely by gastrointestinal routes (ingesting contaminated meat). Inhalation anthrax is of military concern because of its potential for use as a biological warfare agent. Human-to-human transmission is extremely unlikely and only reported with skin anthrax.
Some of the data reported are informations acquired from two sources :
-the Sverdlovsk accident in 1979, in the former Soviet Union, due to accidental release of spores held in a military base (66 people died).
-from a naturally occurring epidemic which took place in Rhodesia-Zimbabwe in 1978-1980 where in those years there were a total of 9700 cases. This epidemic was caused by a disruption of the veterinary infrastructure and cessation of anthrax vaccination in animal because of the war.

Clinical Disease :

Cutaneous Anthrax :
More than 95% of cases of anthrax are cutaneous. After inoculation (the spores penetrate through small wounds or abrasions, apparently they do not penetrates intact skin), the incubation period is 1-5 days. The disease first appears as a small papule that progress over a day or two to a vesicle which may be of 1 to 2 cm in diameter, ruptures, leaving a necrotic ulcer. The ulcer base develops a characteristic black eschar and after a period of 2 to 3 weeks the eschar separates leaving a scar. The lesion is usually painless, & not discharges pus, and varying degree of edema may be present around it. Anthrax lesions are common on the head & neck and exposed arms but rarely on the hands. Patient usually has fever, malaise, and headache, which may be sever in those with extensive oedema. The lesion always resolves slowly, over a period of 2-6 weeks, despite appropriate antimicrobial treatment, and with treatment the mortality should be less than 1%. .

Inhalational Anthrax :
Naturally acquired pulmonary anthrax is a very rare occupational disease affecting those handling infected animal products, for instance wool and hides workers, and dock workers. Wool sorters & workers who are continuously exposed become relatively resistant to infection. Pulmonary Anthrax starts initially with low fever, dry cough, feeling unwell, tiredness, muscle pain, marked sweating, discomfort in the chest, and 1-5 days later, may have sudden onset of high fever and very severe stridor and cyanosis of lips and fingers. Chest X Ray examination usually shows the characteristic widening of the mediastinum (caused by hemorrhagic mediastinitis) and often pleural effusion, but no pulmonary infiltrates. Shock may occur with death in 24-36 hours. Meningitis is present in 50% of cases & mortality has been essentially 100% despite appropriate treatment. Inhalation anthrax study in experimental animals has shown spores are transported by lymphatics to mediastinal lymph nodes, where germination occurs up to 60 days later. These observations were the basis for the recommendation that antibiotics prophylaxis be given for 60 days. In the Serdlovsk accident all cases occurred within six weeks from the accidental discharge of anthrax spores. In the two known outbreaks of inhalation anthrax, mortality rate was 86% in Sverdlovsk and and 45% in the US postal service. Chest x rays of 8 US patients showed enlarged mediastinum ((7 of 8) but also infiltrates and consolidation (6 of 8) confirming autopsy report of Sverdlovsk cases of 75 % pulmonary infiltrates.

Gastrointestinal Anthrax:
It is very rare, thought to arise by consumption of contaminated meat that has not been sufficiently cooked. Ingestion of contaminated water can be a source as well. The presentation is non-specific with feeling sick, vomiting, loss of appetite, fever leading to severe stomach pain, haematemesis and bloody diarrhoea. Sudden death can occur within 2-5 days of onset.

Diagnosis :
The most critical aspect in making a diagnosis of anthrax is a high index of suspicion associated with a compatible history of exposure.
Cutaneous Anthrax should be considered following the development of a painless pruritic papule , vesicle or ulcer – often with surrounding oedema- that develops into a black eschar. Gram’s stain & culture of the lesion will usually confirm the diagnosis. Serological testing and punch biopsy at the edge of the lesion, are useful in diagnosis of anthrax in patients who received antibiotic therapy.
The diagnosis of inhalational anthrax is difficult , but the disease should be suspected with a history of exposure to B anthracis – containing aerosol. The early symptoms are entirely nonspecific. However (1) the development of respiratory distress in association with radiographic evidence of a widened mediastinum due to hemorrhagic mediastinitis, and (2) the presence of hemorrhagic pleural effusion or hemorrhagic meningitis should suggest the diagnosis.
Blood culture and B.anthracis – specific polymerase chain reaction (PCR) of sterile fluid (e.g., blood and pleural fluid ) are important in the diagnosis of inhalational anthrax. Serological tests , immunohistochemical examination of pleural fluid or transbronchial biopsy specimens, has an important role in the diagnosis of inhalational anthrax. None of these are presently available in North Iraqi Kurdistan

Treatment :
Early treatment of all forms is important for recovery. Antibiotic therapy usually results in recovery of the individual or infected animal if given before onset or immediately after onset of illness. Penicillin remains the proven drug of choice for anthrax. Provided there is early treatment of skin anthrax, with oral penicillin; the outcome is very good. If evidence of spreading infection or systemic symptoms present, then i.v. therapy with high dose penicillin ( 2 million units administered every 6 h ) may be initaiated until a clinical response is obtained. Treatment should be continued for 7 to 10 days. Inhalational , oropharyngeal , and gastrointestinal anthrax should be treated with large doses of i.v. Penicillin (2 million units administered every 2 h) with appropriate vasopressors, oxygen, and other supportive therapy ( chest tube drainage of the recurrent hemorrhagic pleural effusions often leads to a dramatic clinical improvement). However concern for Penicillin resistance has been raised regarding the military uses of spores because is very easy to produce Penicillin resistant strain in laboratory. Therefore inhalation Anthrax caused by military use of spores A must be considered caused by Penicillin resistant strains, and treatment should be with ciprofloxacine per os, 1000 mg initially followed by 750 mg bid (twice daily) or doxycycline, 200 mg initially followed by 100 mg bid (twice daily).

Precautions , Prevention & Prophylaxis :
Prevention of anthrax in both humans and animals is based on enforcement of regulatory methods in endemic areas. The population should be encouraged not to eat the meat of animals that become ill or die. Burying their carcasses in lime can reduce the spread of the disease from animals, which have died of anthrax. The most efficient method of disposal is incineration in a manner that ensures heat sterilization of the soil. Bandages, clothing and other contaminated materials should be disposed of, preferably by burning, as spores are very resistant to normal decontamination methods. Once a case is suspected, the local health authorities must be informed immediately. In case of military use of spore, an anthrax attack, the situation is different because of the possibility of Penicillin resistance of the strain. Experimental evidence has demonstrated that treatment with antibiotics beginning 1 day after exposure to lethal aerosol challenge with anthrax spores can provide significant protection against death. During recent bioterrorist attack, interim CDC (Center for Diseases control) recommendations for anthrax prophylaxis include Ciproflaxacin or Doxycycline. Amoxicillin is an option for children & pregnant or lactating women to avoid the potential toxicity of quinolones & tetracyclines. However in the case of inhalation anthrax from military use amoxicillin will not be appropriate and one has to balance the risk of cyprofloxacin for pregnat womency against the risk of a lethal disease. The dose options of prophylaxis for anthrax attack is therefore : Ciprofloxacin 500 mg bid, or doxycycline 100 mg bid. If the attack is confirmed vaccination, if available, should be given, while antibiotics should be continued for four weeks.
Where possible three options are now offered regarding duration of prophylaxis:

  1. 60 days of antibiotic prophylaxis.
  2. 100 days of antibiotic prophylaxis
  3. 100 days of antibiotic prophylaxis + anthrax vaccine[3 doses over 4-week period].

  4. Prophylaxis is indicated for persons exposed to an airspace contaminated with aerosolized B. anthracis .
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