Anthrax

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Anthrax
A skin lesion with black eschar characteristic of anthrax
Specialty	Infectious disease
Symptoms	Skin form: small blister with surrounding swelling Inhalational form: fever, chest pain, shortness of breath Intestinal form: nausea, vomiting, diarrhea, abdominal pain Injection form: fever, abscess[1]
Usual onset	1 day to 2 months post contact[1]
Causes	Bacillus anthracis[2]
Risk factors	Working with animals; travelers, postal workers, military personnel[3]
Diagnostic method	Based on antibodies or toxin in the blood, microbial culture[4]
Prevention	Anthrax vaccination, antibiotics[3][5]
Treatment	Antibiotics, antitoxin[6]
Prognosis	20–80% die without treatment[5][7]
Frequency	>2,000 cases per year[8]

Anthrax is an infection caused by the bacterium Bacillus anthracis or Bacillus cereus biovar anthracis.^[2] Infection typically occurs by contact with the skin, inhalation, or intestinal absorption.^[9] Symptom onset occurs between one day and more than two months after the infection is contracted.^[1] The skin form presents with a small blister with surrounding swelling that often turns into a painless ulcer with a black center.^[1] The inhalation form presents with fever, chest pain, and shortness of breath.^[1] The intestinal form presents with diarrhea (which may contain blood), abdominal pains, nausea, and vomiting.^[1]

According to the U.S. Centers for Disease Control and Prevention, the first clinical descriptions of cutaneous anthrax were given by Maret in 1752 and Fournier in 1769. Before that, anthrax had been described only in historical accounts. The German scientist Robert Koch was the first to identify Bacillus anthracis as the bacterium that causes anthrax.

Anthrax is spread by contact with the bacterium's spores, which often appear in infectious animal products.^[10] Contact is by breathing or eating or through an area of broken skin.^[10] It does not typically spread directly between people.^[10] Risk factors include people who work with animals or animal products, and military personnel.^[3] Diagnosis can be confirmed by finding antibodies or the toxin in the blood or by culture of a sample from the infected site.^[4]

Anthrax vaccination is recommended for people at high risk of infection.^[3] Immunizing animals against anthrax is recommended in areas where previous infections have occurred.^[10] A two-month course of antibiotics such as ciprofloxacin, levofloxacin and doxycycline after exposure can also prevent infection.^[5] If infection occurs, treatment is with antibiotics and possibly antitoxin.^[6] The type and number of antibiotics used depend on the type of infection.^[5] Antitoxin is recommended for those with widespread infection.^[5]

A rare disease, human anthrax is most common in Africa and central and southern Asia.^[11] It also occurs more regularly in Southern Europe than elsewhere on the continent and is uncommon in Northern Europe and North America.^[12] Globally, at least 2,000 cases occur a year, with about two cases a year in the United States.^[8][13] Skin infections represent more than 95% of cases.^[7] Without treatment the risk of death from skin anthrax is 23.7%.^[5] For intestinal infection the risk of death is 25 to 75%, while respiratory anthrax has a mortality of 50 to 80%, even with treatment.^[5][7] Until the 20th century anthrax infections killed hundreds of thousands of people and animals each year.^[14] In herbivorous animals infection occurs when they eat or breathe in the spores while grazing.^[11] Animals may become infected by killing and/or eating infected animals.^[11]

Several countries have developed anthrax as a weapon.^[7] It has been used in biowarfare and bioterrorism since 1914. In 1975, the Biological Weapons Convention prohibited the "development, production and stockpiling" of biological weapons. It has since been used in bioterrorism. Likely delivery methods of weaponized anthrax include aerial dispersal or dispersal through livestock; notable bioterrorism uses include the 2001 anthrax attacks and an incident in 1993 by the Aum Shinrikyo group.