NPR Report:
- LINK -

Wash Post Video:
- LINK -

CDC Article:
- LINK -

USUHS Links:
- LINK -

Anthrax is an infectious disease caused by the spore of the aerobic gram-positive encapsulated bacterium Bacillus anthracis. It primarily affects animals (cattle, sheep, goats, camels, antelopes, and other herbivores). Humans are secondary affects usually as occupational contact with infected animals and through breathing spores of the bacilli. Prior to the recent terrorist activities, the disease was almost exclusively restricted to the occupational exposure.

There are three types of anthrax infection: cutaneous, gastrointestinal, and inhalation.

Anthrax gets its name from the Greek word for coal, anthrakis, because the cutaneous lesions produce a black skin lesion. Initially the lesion looks like a mosquito bite but progresses to a painless ulcer which then forms a black eschar. Cutaneous anthrax is contracted through a cut or scrape on the skin and therefore is generally found on unexposed skin of the hand, arms, face, and neck. Approximately 20% of untreated patients die from this form, however with antibiotic treatment death is rare.

Gastrointestinal anthrax is cause by ingestion of poorly cooked infected meat and includes two forms - an oral-pharyngeal and an abdominal form. The oral-pharyngeal form presents with ulceration which can lead to regional lymphadenopathy, edema and sepsis. The abdominal form develops lesions primarily in the terminal ileum or cecum and presents with nausea, vomiting, malaise, bloody diarrhea, acute abdomen, ascites and sepsis. The advance infections may appear similar to the sepsis seen with cutaneous or inhalation anthrax. Gastrointestinal anthrax is rarely reported. Early diagnosis is difficult; with delays in treatment mortality is likely high.

Inhalation anthrax is caused, as its name suggests, by inhalation of the anthrax spore. The spores are ingested by macrophages and transported to the mediastinal lymph nodes where germination occurs. Replicating bacteria release toxins leading to hemorrhage, edema, and necrosis. Initial symptoms are nonspecific including fever, dyspnea, nonproductive cough, headache, vomiting, chills, weakness, abdominal pain, and chest pain. This is followed by sudden fever, dyspnea, diaphoresis and shock. Death can occur within hours from this second stage. Radiographically the hemorrhagic thoracic lymphadenitis and hemorrhagic mediastinitis causes a widened medistinum. Pleural effusions are common.Nonspecific airspace disease is caused by focal hemorrhagic necrotizing pneumonic lesions and is not due to an anthrax pneumonia. 50% of the patients also have hemorrhagic meningitis causing meningismus, delirium and obtundation. The mortality rate for occupationally acquired inhalation anthrax in the US is 89%.

The cases of inhalational anthrax shown here demonstrate peribronchial and perivascular infiltration that is caused by engorged lymphatics. The appearence on CT is very similar to that of lymphangitic spread of metastatic carcinoma.


Anthrax NPR Report:
- LINK -