History: Anthrax has been known since ancient times. Besides some references in the Old Testament, there is evidence of plagues in ancient Egypt, as well as descriptions of the disease by the Roman poet Virgil.
Etiology: Anthrax is caused by Bacillus anthracis, unmovable, aerobic, gram-positive rods. It forms spores, which can survive for years in the environment.
Pathogenesis: Capsular polypeptide and anthrax toxin are the principal virulence factors of Bacillus anthracis. Anthrax toxin consists of three proteins called protective antigen, edema factor, and lethal factor. It is thought that the inflammatory mediator--lethal factor is stored within the macrophage during the early stage of infection. It is rapidly released in large amounts into the blood stream and once the threshold for lysis is reached, it may be the cause of sudden death.
Epidemiology: Grass-eating animals are usually infected by the bacilli from grass and ground. The disease is transmitted to people by contact with the sick animals or their products, such as wool, skin, meat etc.
Clinical features: Two clinical forms exist: outer--cutaneous and inner, including inhalation and gastrointestinal anthrax. While cutaneous anthrax is easily cured, the inner forms have high mortality rates. DIAGNOSIS AND DIFFERENTIAL DIAGNOSIS: The diagnosis is easily established in cutaneous cases, characterized by black eschar. Severe intoxication and collapse during the course of bronchopneumonia or hemorrhagic enteritis should arise suspicion of anthrax.
Therapy: Hospitalization of patients is mandatory. Bacillus anthracis is susceptible to a number of antibiotics, including penicillin, erythromycin, tetracyclines, cephalosporins etc.
Prevention: General veterinary prevention including vaccination of livestock and control of products is very important. The vaccine consists of anthrax bacillus that is attenuated. The endangered population, such as animal workers and military personnel should be vaccinated. Annual schedule of booster immunization must be maintained. ANTHRAX AS A BIOLOGICAL WEAPON: Anthrax has been developed as a weapon of mass destruction since World War I. During accidental release from a biological warfare factory in the former Soviet Union, 68 people died. The ease of laboratory production and its dissemination via aerosol led to its adoption by terrorists, as shown by recent happenings in the USA.
Conclusion: A good knowledge of anthrax, its transmission and potentials as a biological weapon is essential for timely prevention and protection.