Most of these cases occur in underdeveloped countries worldwide. The remainder results in hematogenous spread, sepsis, meningitis, and death. Only a handful of cases have been reported within the past 20 years. This is the result of poor or nonexistent livestock vaccination programs, ineffective public education programs, and the continued contact with and consumption of animals that are obviously ill or infected.
Exposure is via contaminated skin of infected animals, which often are sheep or cattle.
After an incubation period of 3-4 days, a lesion appears that frequently is confused with an insect bite. Usually, the lesion is painless and may be noticed first because of associated pruritus and surrounding redness. A lesion begins as a pruritic papule. The papule enlarges and develops into an ulcer surrounded by vesicles, which usually occurs within 1-2 days. A characteristic black necrotic eschar appears with associated edema and surrounding erythema.