ERLICHIOSIS - ANOTHER HUMAN TICK-BORNE DISEASE

Ehrlichiosis is an animal disease caused by the genus Ehrlichia (rickettsial agents), and usually associated with canines in the United States. Ehrlichiosis as a human disease was recognized in 1986. Through 1989, 173 serologically proven cases were reported by CDC. Ehrlichia canis is most probably responsible for the illness, with the pattern of transmission being tick-borne. The brown dog tick, Rhipicephalus sanguineus, has been suggested as a probable vector, even though it reportedly bites humans infrequently. Is this tick possibly adapting itself to human hosts? Or could there be a common vector and/or reservoir not yet identified? The illness is strikingly similar to Rocky Mountain Spotted Fever, except that the rash is only transient. The agent has not been isolated and diagnosis is based on laboratory tests.