Anaplasmosis is a tick-borne infection that can sometimes be severe or fatal. Anaplasmosis is caused by the bacteria, Anaplasma phagocytophilum. It cannot be spread from person-to-person.

You may develop anaplasmosis if you are bitten by an infected blacklegged tick. A tick must be attached to a person's skin for at least 12 to 24 hours to transmit the bacteria that cause anaplasmosis. Most infections occur during the spring, summer and fall when ticks are most active. There has recently been a rise in cases of anaplasmosis in NYC. Fewer than 100 cases are reported in the city per year.


Symptoms typically begin one to two weeks after a bite and may include:

  • Fever
  • Chills
  • Severe headache
  • Muscle aches
  • Nausea
  • Vomiting
  • Diarrhea
  • Loss of appetite

More severe illness is rare but may occur if treatment is delayed or if there are underlying medical conditions. Complications can include:

  • Respiratory failure
  • Bleeding problems
  • Organ failure


To prevent anaplasmosis, be aware of where ticks are present. Blacklegged ticks have been found in Staten Island and parts of the north Bronx. Other areas outside of NYC include Long Island, upstate NY, northeast states, Minnesota and Wisconsin.

Learn how to prevent ticks and tick bites.


Early treatment with an antibiotic, usually doxycycline, can prevent severe illness

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