Anthrax: A Primer

Anthrax was the first disease known to be caused by a microbe. Robert Koch discovered that infectious diseases are caused by microbes by studying anthrax in cattle in 1877. The steps Koch followed to prove that a specific microbe causes a disease, Koch's Postulates, are still used.

Human anthrax is rare in the United States, but occurrences in herbivores are not uncommon. Imported goat hair and handicrafts containing animal hides have been a source of infection in the United States.

Anthrax is usually acquired through breaks in skin through which spores enter. The spores germinate to yield vegetative cells which multiple locally or spread.

The disease is spead by spores in pastures contaminated with exudates of infected animals.

Herbivores such as horses, sheep, and cattle are most commonly affected and develop fatal septicemia. Humans are usually infected by contact with infected animals or animal products. Because of the long survival of spores, infection may result from contaminated hides, wool, bone, and even processed items such as bone meal fertilizer.