Section 11 Anthrax

Introduction of Anthrax

Anthrax is an acute zoonosis caused by Bacillus anthracis，mostly infesting herbivores，herdsmen and farmers. Dormant infection of anthrax is more common among leather workers.

Anthrax among human beings spreads via direct or indirect contact to contaminated animals. Patients’sputum，feces and secretions from lesions are infectious. Pathogen of anthrax is transmitted by cutaneous contact，digestive and respiratory tract. Immunity to anthrax is enduring following a natural attack. Bacillus anthracis is able to maintain a cell-spore-cell cycle for many years with the spore being very resistant to harsh surroundings. In rural areas，diseased cattle that are killed and stripped can contaminate a large area of land and water，making it difficult to control. Thus anthrax relapses frequently in the epidemic area.

There are three types of anthrax：

1. Skin anthrax

Skin anthrax accounts for 98% of all anthrax cases. Anthrax lesions often occur on naked skin，appearing papules or macula in the beginning followed by vesicles containing yellowish liquid surrounded by swollen hard tissues. 3-4 days later，center of the lesions becomes hemorrhagic necrosis and dents，surrounded by clusters of small vesicles.5-7 days later，with the edema area expanding，the necrotic area erupts and the hemorrhagic secretions clot，forming dry and black carbuncle. Granulation tissue grows under the carbuncle. With the edema fading，the carbuncle falls off within 1-2 weeks leaving a lesion that made of granulation tissue and healing a scar within another 1-2 weeks. Pain in the lesion is not violent but itching is common，accompanied by systemic reaction including fever，headache，malaise，local lymphadenectasis and splenomegaly，etc.

2. Intestinal anthrax

Intestinal anthrax often manifests as mild or severe acute gastro-enteritis type or surgical abdomen type. The acute gastro-enteritis has a short incubation period （12-18h） erupting suddenly and manifesting constant vomiting，hematemesis，blood-stained stool，flatulence，abdominal pain，tenderness，diarrhea or signs of peritonitis. Patients of this type may die due to sepsis or septic shock.

3. Pulmonary anthrax

This type occurs acutely or occurs after 2-4 days of precursor symptoms including low fever，myalgia，dry cough and tenderness in cardiac areas. The pulmonary symptoms appear suddenly manifesting high fever，short breath，wheeze，cyanosis，cough，blood-stained sputum，chest pain，sweating，tachycardia，pulmonary inflammation，and pleural effusion. This type is critical and has high mortality，being prone to death due to respiratory failure，given less competent emergency treatment.

Penicillins are the drugs of first choice for anthrax.

炭疽流行病学个案调查表

Epidemiological Questionnaire for Cases of Anthrax

Questionnaire

（本节编者-刘文辉　本节核对-刘方华　龙佳丽）