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Anaplasmosis, also known as human granulocytic anaplasmosis, is a disease caused by the bacterium Anaplasma phagocytophilum. Ixodes ticks, can carry this bacteria. To date, there have been no reported human cases in British Columbia, but the bacteria has been found in ticks sampled on southern Vancouver Island. Two human cases of anaplasmosis have been reported in nearby Mason and Pierce County, Washington, USA, in 2022. There have been reports of anaplasmosis in dogs on Vancouver Island that did not travel off the island.

Information for Health Professionals

A. phagocytophilum, a bacteria in the Rickettsia genus, is spread by the bite of an infected tick and can be carried by Ixodes pacificus (western blacklegged tick) in BC. In extremely rare cases, A. phagocytophilum has been spread by blood transfusion.

Within 1-2 weeks after exposure, the following symptoms may occur:
  • Fever, chills
  • Severe headache
  • Nausea, vomiting, diarrhea, loss of appetite 
  • Muscle aches
Although less common, illness can progress and cause:
  • Respiratory failure
  • Bleeding problems
  • Organ failure
  • Death
Some people may not experience any symptoms despite being infected. 
Laboratory diagnostic testing can include the following:
  • Nucleic acid amplification test (NAAT)
  • Serology (indirect immunofluorescence antibody (IFA) assay)
  • Microscopic examination of a peripheral blood smear
Early treatment with antibiotics is recommended. Awareness and avoidance are best to prevent this disease.

If anaplasmosis is diagnosed or suspected, your doctor may prescribe antibiotics to ensure the best possible result.

Find more information about prevention of anaplasmosis on the main tick-borne diseases page.

SOURCE: Anaplasmosis ( )
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