anthrax

[an´thraks]

an infectious disease seen most often in cattle, horses, mules, sheep, and goats, due to ingestion of spores of Bacillus anthracis. It can be acquired by humans through contact with infected animals or their byproducts, such as carcasses or skins.

Anthrax in humans usually occurs as a malignant pustule or malignant edema of the skin. In rare instances it can affect the lungs if the spores of the bacillus are inhaled, or it can involve the intestinal tract when infected meat is eaten. The condition often is accompanied by hemorrhage, as the exotoxins from the bacillus attack the endothelium of small blood vessels. The condition is treated by the use of antibiotics such as penicillin and the tetracyclines. The malignant edema can be treated with intravenous hydrocortisone. The disorder is also known by a variety of names, including woolsorters' disease, ragpickers' disease, and charbon.

cutaneous anthrax anthrax due to lodgment of the causative organisms in wounds or abrasions of the skin, producing a black crusted pustule on a broad zone of edema.

gastrointestinal anthrax anthrax due to ingestion of poorly cooked meat contaminated with Bacillus anthracis, with deposition of spores in the submucosa of the intestinal tract, where they germinate, multiply, and produce toxin, resulting in massive edema, which may obstruct the bowel, hemorrhage, and necrosis.

inhalational anthrax a usually fatal form of anthrax due to inhalation of dust containing anthrax spores, which are transported to the regional lymph nodes where they germinate, multiply, and produce toxin, and characterized by hemorrhagic edematous mediastinitis, pleural effusions, dyspnea, cyanosis, stridor, and shock. It is usually an occupational disease, such as in persons who handle or sort contaminated wools and fleeces. Antimicrobial prophylaxis is used to prevent the condition. The Centers for Disease Control and Prevention has published interim guidelines for investigation and response to Bacillus anthracis infection. The evaluation of risk for exposure to aerosolized spores is of highest priority. Obtaining adequate samples, avoiding cross-contamination, and insuring proficient testing and evaluation of test results are all recommended.

meningeal anthrax a rare, usually fatal form of anthrax resembling typical hemorrhagic meningitis due to spread through the bloodstream of Bacillus anthracis from a primary focus of infection; manifestations include cerebrospinal fluid that is hemorrhagic and neurological signs and symptoms.

pulmonary anthrax inhalational anthrax.

inhalational anthrax

a form of anthrax acquired by breathing in spores of Bacillus anthracis in airborne particles less than 5 mcg. The spores are then phagocytized in lung alveoli by macrophages and carried to lymph nodes in the mediastinum where hemorrhage mediastinitis ensues. The classic radiographic finding in inhalational anthrax is a widened mediastinum on plain chest radiograph or chest CT scan. Early diagnosis of inhalational anthrax is difficult because initial symptoms are nonspecific chills, fever, muscle aches, cough. After 1-3 days, dyspnea, hypotension, high fever, and stridor become the primary symptoms. Mortality for inhalational anthrax approaches 100%, even with treatment.

Farlex Partner Medical Dictionary © Farlex 2012

anthrax

An often fatal bacterial infection that occurs when Bacillus anthracis endospores (primarily of grazing herbivorous—cattle, sheep, horses, mules—origin) enter via skin abrasions, inhalation or orally.

Diagnosis
ELISA for capsule antigens (95+% senstivity) and protective antigens (72% sensitivity); detection of exotoxins in blood is unreliable.

Prevention
Prophylaxis (six weeks) with doxycycline or ciprofloxacin; vaccination with anthrax vaccine absorbed; decontamination with aerosolised formalin.

Management
Penicillin, doxycycline; chloramphenicol, erythromycin, tetracycline, ciprofloxacin if (allergic to penicillin).

Anthrax, clinical forms
Inhalation (Anthrax pneumonia, inhalational anthrax, pulmonary anthrax)
An almost universally fatal form due to inhalation of 1 to 2 µm pathogenic endospores, which are deposited in alveoli, engulfed by macrophages and germinate en route to the mediasitinal and peribronchial lymph nodes, producing toxins.

Clinical
Mediastinal widening, pleural effusions, fever, nonproductive cough, myalgia, malaise, haemorrhage, cyanosis, SOB, stridor, shock, death; often accompanied by mesenteric lymphadenitis, diffuse abdominal pain and fever.

Cutaneous
Once common among handlers of infected animals (e.g., farmers, wool-sorters, tanners, brushmakers and carpetmakers).

Clinical
Carbuncle, a cluster of boils that later ulcerates, resulting in a hard black centre surrounded by bright red inflammation; rare cases that become systemic are almost 100% fatal.

Gastrointestinal
After ingesting contaminated meat (2 to 5 days); once ingested, spores germinate, causing ulceration, haemorrhagic and necrotising gastroenteritis.

Clinical
Fever, diffuse abdominal pain with rebound tenderness, melanic stools, coffee grounds vomit, fluid and electrolyte imbalances, shock; death is due to intestinal perforation or anthrax toxemia.

Oropharyngeal
Uncommon; follows ingestion of contaminated meat.

Clinical
Cervical oedema, lymphadenopathy (causing dysphagia), respiratory difficulty.

Anthrax meningitis
A rare, usually fatal complication of GI or inhalation anthrax, with death occurring 1 to 6 days after onset of illness.

Clinical
Meningeal symptoms, nuchal rigidity, fever, fatigue, myalgia, headache, nausea, vomiting, agitation, seizures, delirium, followed by neurologic degeneration and death.

in·ha·la·tion·al an·thrax

(inhă-lāshŭn-ăl anthraks)

Disease acquired by breathing in spores of Bacillus anthracis in airborne particles less than 5 mcg. Early diagnosis of inhalational anthrax is difficult because initial symptoms are nonspecific chills, fever, muscle aches, cough. After 1-3 days, dyspnea, hypotension, high fever, and stridor become the primary symptoms; mortality nears 100%, even with treatment.