Anaplasmosis

Anaplasmosis is caused by a bacterium that infects a specific kind of white blood cell. The vector is the blacklegged tick — the same species responsible for Lyme disease — so the geography of risk overlaps almost completely with Lyme. A single tick can carry both, which is why co-infections are common.

Like Lyme, anaplasmosis transmission generally requires extended attachment — on the order of 24 hours. Quick removal cuts the risk dramatically.

One to two weeks after a bite, anaplasmosis comes on like a bad flu:

• High fever
• Severe headache
• Muscle aches
• Chills and shaking
• Fatigue
• Sometimes nausea or vomiting

Notably absent: cough, sore throat, runny nose. If a flu-like illness in summer doesn’t have respiratory symptoms, anaplasmosis is on the differential — especially after outdoor time. Lab work typically shows low platelets, low white-cell count, and elevated liver enzymes.

This week:a flu-like illness with high fever and severe headache, one to two weeks after time outdoors in a Lyme area, with no respiratory symptoms. Tell your doctor about the exposure — anaplasmosis isn’t always front of mind.

Emergency room: confusion, severe shortness of breath, or signs of shock. Severe anaplasmosis can damage organs, especially in older or immunocompromised patients.

Anaplasmosis is treated with doxycycline. Most people respond within 24–48 hours of starting antibiotics. Diagnosis is usually clinical (symptoms plus exposure history) with confirmation from blood work — treatment shouldn’t wait for the lab result.

Anaplasmosis follows the blacklegged tick: southern Ontario, southern Quebec, Nova Scotia, and New Brunswick, with emerging activity in southeastern Manitoba and the BC south coast. Quebec’s Estrie region in particular has seen a notable rise over the past several years.

Public Health Agency of Canada (anaplasmosis health-professional guidance); Canada Communicable Disease Report (Estrie regional case series).