Human ehrlichiosis--an overview.

Canine ehrlichiosis, previously thought to be restricted to dogs, has gained prominence in the human population since 1986. In the United States, human ehrlichiosis is a newly recognized disease ranging from a mild infection to a severe life threatening or fatal disease. Since antibody titers were found to be highest to E. canis in human ehrlichiosis patients, it was believed that E. canis or a closely related species was the etiologic agent. Investigators from the Centers for Disease Control recently have isolated a bacterium believed to be the etiologic agent of human ehrlichiosis and proposed the name Ehrlichia chaffeensis. Human cases of the disease have been identified primarily in the southeastern and south-central areas of the United States. Although relatively few cases are diagnosed, Oklahoma, according to one source, has been found to have the highest incidence rate. The human disease could be misdiagnosed as Rocky Mountain spotted fever, murine typhus fever, or Q fever.