Anaplasma, Coxiella, Ehrlichia, and Rickettsia spp. were previously considered as members of the same family but are now considered distinct entities based on genetic analysis. These groups of organisms are bacteria but only grow inside living cells.
Common names for disease: Anaplasmosis, human granulocytic anaplasmosis (HGA), previously described as human granulocytic ehrlichiosis (HGE)
Ranchers, farmers, foresters, rangers, hunters, lumberjacks, landscapers, outdoor workers, veterinarians, and research and laboratory technicians are at increased risk of exposure.
Anaplasma is transmitted to humans by the bite of an infected tick. The blacklegged tick (Ixodes scapularis) is the vector of Anaplasma phagocytophilum in the northeast and upper midwestern United States, and the western blacklegged tick (Ixodes pacificus) is the primary vector in Northern California (Figure 25.1).1 Cases have also been confirmed in several European and Asian countries.