Anthrax

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Anthrax is an acute zoonotic infectious disease caused by the bacterium Bacillus anthracis. It most commonly occurs in wild and domestic animals, such as cattle, sheep, goats, camels, antelopes, and other herbivores. B. anthracis spores can live in the soil for many years.

It occurs in humans when they are exposed to infected animals or tissue from infected animals. The incubation period is usually 1-3 days. Anthrax is a notifiable disease.

Cause

  • Exposure to B. anthracis spores by handling products from infected animals or by inhaling anthrax spores from contaminated animal products
  • Anthrax can also be spread by eating undercooked meat from infected animals

Clinical features

Symptoms vary depending on how the disease was contracted, and usually occur within 7 days

TYPE

FEATURES

Cutaneous

95% of anthrax infections occur through skin cut or abrasion

Starts as raised itchy bump that resembles an insect bite

Within 1-2 days, it develops into a vesicle and then a painless ulcer, usually 1-3 cm in diameter, with a characteristic black necrotic (dying) area in the centre (eschar)

Lymph glands in adjacent area may swell

About 20% of untreated cutaneous anthrax results in death

Inhalation

Initial symptoms resemble a cold

After several days, symptoms may progress to severe breathing problems and shock

Inhalation anthrax is usually fatal

Gastro-intestinal

Acute inflammation of the intestinal tract

Initial signs of nausea, loss of appetite, vomiting and fever

Then abdominal pain, vomiting blood, and severe diarrhoea

Intestinal anthrax results in death in 25% to 60% of the cases

Investigations

  • Isolation of Bacillus anthracis from blood, skin lesions, or respiratory secretions
  • Or measure specific antibodies in the blood of persons with suspected infection

Management

Treatment LOC

Cutaneous anthrax

  • Treat for 7–10 days
  • First line is ciprofloxacin 500 mg every 12 hours
  • Alternatives: doxycycline 100 mg every 12 hours
  • Or amoxicillin 1g every 8 hours       
 HC2

 

Prevention

The following public measures are key for quick prevention and control of anthrax infection:

  • Health education and information
  • Proper disposal by burying of carcasses, hides and skins; (no burning as it can spread spores)
  • No skinning of dead animals; this allows spore formation, which can stay in soil for decades
  • No eating of meat from dead animals
  • Restrict movement of animals and animal by-products from infected to non-infected areas
  • Mass vaccination of animals in endemic areas
  • Vaccination using human anthrax vaccine for:
    • Persons who work directly with the organism in the laboratory
    • Persons who handle potentially infected animal products in high-incidence areas