Clinical Features

There are three distinct types of anthrax in humans:

• Cutaneous
• Inhalational
• Gastrointestinal disease

Cutaneous anthrax scabs. Medical attention should begin before apperance of symptoms.

Cutaneous anthrax occurs most frequently on the hands and forearms of persons working with infected livestock. It begins as a blister followed by formation of a fluid-filled vesicle. The vesicle typically dries and forms a coal-black scab, hence the term anthrax (from the Greek for coal). This local infection can lead to a fatal systemic infection.

Endemic inhalational anthrax, known as Wool sorters' disease, is also a rare infection contracted by inhalation of the spores. It occurs mainly among workers in an industrial setting handling infected hides, wool, and furs.

Gastrointestinal anthrax is rare in humans, and is contracted by the ingestion of insufficiently cooked meat from infected animals.

The death rate for untreated or late treated anthrax:

• Cutaneous (skin) 25%
• Inhalational 100%
• Intestinal 100%

Mortality Rates

In man, the mortality of untreated cutaneous (skin) anthrax ranges up to 25 per cent; in inhalational and intestinal cases, the case fatality rate is almost 100 %.

Diagnosis

After an incubation period of 1-6 days the onset of inhalation anthrax is gradual and nonspecific. (During an outbreak of inhalational anthrax in the Soviet Union in 1979, persons are reported to have become ill up to 6 weeks after an aerosol release occurred.)

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 (hours to 2-3 days), followed by the abrupt development of severe respiratory distress. Serious bacterial infection, 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. Pneumonia generally does not occur. Approximately 50% of cases are accompanied by hemorrhagic meningitis.

Medical Management

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. However, penicillin-resistant strains exist naturally, and one has been recovered from a fatal human case.

Tetracyclines and erythromycin have been recommended in penicillin allergic patients. It might not be difficult for an adversary to induce resistance to penicillin, tetracyclines, erythromycin, and many other antibiotics through laboratory manipulation of organisms.

All naturally occurring strains tested to date have been sensitive to erythromycin, chloramphenicol, gentamicin, and ciprofloxacin.

Published recommendations from a public health consensus panel recommends ciprofloxacin as initial therapy. Therapy may then be tailored once antibiotic sensitivity is available to penicillin G or doxycycline. Recommended treatment duration is 60 days and should be changed to oral therapy as clinical condition improves. Supportive therapy for shock, fluid volume deficit, and adequacy 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.