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Anaplasmosis is an infection caused by the bacterium Anaplasma phagocytophilum and is transmitted to humans by the bite of an infected tick (Ixodes pacificus or Ixodes scapularis). Anaplasmosis is most frequently reported in the upper midwestern and northeastern United States; it is very uncommon in California.

Anaplasmosis is reportable in Orange County within seven (7) calendar days of identification. To report a case, health care providers/facilities should call OCHCA Epidemiology at 714-834-8180, fax reports to 714-560-4050, or mail to P.O. Box 6128, Santa Ana, CA 92706-0128. Two to eight (2-8) cases of anaplasmosis were reported in California each year between 2011 and 2016, with none in Orange County.

Last reviewed November 27, 2018