Anthrax is a disease that is present in the soil and occurs naturally in livestock, including pigs, horses, goats, cattle, and sheep. Farmers who work with these animals have been known to contract anthrax. Human-to-human contact has not been documented and is thought to be unlikely. Infection occurs from skin contact with infected animal tissue and possibly from biting fleas feeding on the animals. The bacterium enters a cut or abrasion on the skin while handling contaminated products from infected animals. Most commonly, the disease appears on the hands and forearms of people working with infected animals (Figure 8.43).