Babesiosis is caused by intraerythrocytic protozoa of the genus Babesia. B. microti, the cause of most cases, is the etiologic agent in the northeastern and upper midwestern United States, B. duncani is responsible for disease on the West Coast, and B. divergens–like organisms cause disease in Arkansas, Kentucky, Missouri, and Washington. The deer tick (Ixodes scapularis) transmits B. microti.

There's more to see -- the rest of this topic is available only to subscribers.